[rust-lightning] / src / ln / channelmonitor.rs

//! The logic to monitor for on-chain transactions and create the relevant claim responses lives
//! here.
//!
//! ChannelMonitor objects are generated by ChannelManager in response to relevant
//! messages/actions, and MUST be persisted to disk (and, preferably, remotely) before progress can
//! be made in responding to certain messages, see ManyChannelMonitor for more.
//!
//! Note that ChannelMonitors are an important part of the lightning trust model and a copy of the
//! latest ChannelMonitor must always be actively monitoring for chain updates (and no out-of-date
//! ChannelMonitors should do so). Thus, if you're building rust-lightning into an HSM or other
//! security-domain-separated system design, you should consider having multiple paths for
//! ChannelMonitors to get out of the HSM and onto monitoring devices.

use bitcoin::blockdata::block::BlockHeader;
use bitcoin::blockdata::transaction::{TxIn,TxOut,SigHashType,Transaction};
use bitcoin::blockdata::transaction::OutPoint as BitcoinOutPoint;
use bitcoin::blockdata::script::{Script, Builder};
use bitcoin::blockdata::opcodes;
use bitcoin::consensus::encode::{self, Decodable, Encodable};
use bitcoin::util::hash::BitcoinHash;
use bitcoin::util::bip143;

use bitcoin_hashes::Hash;
use bitcoin_hashes::sha256::Hash as Sha256;
use bitcoin_hashes::hash160::Hash as Hash160;
use bitcoin_hashes::sha256d::Hash as Sha256dHash;

use secp256k1::{Secp256k1,Signature};
use secp256k1::key::{SecretKey,PublicKey};
use secp256k1;

use ln::msgs::DecodeError;
use ln::chan_utils;
use ln::chan_utils::HTLCOutputInCommitment;
use ln::channelmanager::{HTLCSource, PaymentPreimage, PaymentHash};
use ln::channel::{ACCEPTED_HTLC_SCRIPT_WEIGHT, OFFERED_HTLC_SCRIPT_WEIGHT};
use chain::chaininterface::{ChainListener, ChainWatchInterface, BroadcasterInterface};
use chain::transaction::OutPoint;
use chain::keysinterface::SpendableOutputDescriptor;
use util::logger::Logger;
use util::ser::{ReadableArgs, Readable, Writer, Writeable, WriterWriteAdaptor, U48};
use util::{byte_utils, events};

use std::collections::{HashMap, hash_map};
use std::sync::{Arc,Mutex};
use std::{hash,cmp, mem};

/// An error enum representing a failure to persist a channel monitor update.
#[derive(Clone)]
pub enum ChannelMonitorUpdateErr {
        /// Used to indicate a temporary failure (eg connection to a watchtower or remote backup of
        /// our state failed, but is expected to succeed at some point in the future).
        ///
        /// Such a failure will "freeze" a channel, preventing us from revoking old states or
        /// submitting new commitment transactions to the remote party.
        /// ChannelManager::test_restore_channel_monitor can be used to retry the update(s) and restore
        /// the channel to an operational state.
        ///
        /// Note that continuing to operate when no copy of the updated ChannelMonitor could be
        /// persisted is unsafe - if you failed to store the update on your own local disk you should
        /// instead return PermanentFailure to force closure of the channel ASAP.
        ///
        /// Even when a channel has been "frozen" updates to the ChannelMonitor can continue to occur
        /// (eg if an inbound HTLC which we forwarded was claimed upstream resulting in us attempting
        /// to claim it on this channel) and those updates must be applied wherever they can be. At
        /// least one such updated ChannelMonitor must be persisted otherwise PermanentFailure should
        /// be returned to get things on-chain ASAP using only the in-memory copy. Obviously updates to
        /// the channel which would invalidate previous ChannelMonitors are not made when a channel has
        /// been "frozen".
        ///
        /// Note that even if updates made after TemporaryFailure succeed you must still call
        /// test_restore_channel_monitor to ensure you have the latest monitor and re-enable normal
        /// channel operation.
        ///
        /// For deployments where a copy of ChannelMonitors and other local state are backed up in a
        /// remote location (with local copies persisted immediately), it is anticipated that all
        /// updates will return TemporaryFailure until the remote copies could be updated.
        TemporaryFailure,
        /// Used to indicate no further channel monitor updates will be allowed (eg we've moved on to a
        /// different watchtower and cannot update with all watchtowers that were previously informed
        /// of this channel). This will force-close the channel in question.
        ///
        /// Should also be used to indicate a failure to update the local copy of the channel monitor.
        PermanentFailure,
}

/// General Err type for ChannelMonitor actions. Generally, this implies that the data provided is
/// inconsistent with the ChannelMonitor being called. eg for ChannelMonitor::insert_combine this
/// means you tried to merge two monitors for different channels or for a channel which was
/// restored from a backup and then generated new commitment updates.
/// Contains a human-readable error message.
#[derive(Debug)]
pub struct MonitorUpdateError(pub &'static str);

/// Simple structure send back by ManyChannelMonitor in case of HTLC detected onchain from a
/// forward channel and from which info are needed to update HTLC in a backward channel.
pub struct HTLCUpdate {
        pub(super) payment_hash: PaymentHash,
        pub(super) payment_preimage: Option<PaymentPreimage>,
        pub(super) source: HTLCSource
}

/// Simple trait indicating ability to track a set of ChannelMonitors and multiplex events between
/// them. Generally should be implemented by keeping a local SimpleManyChannelMonitor and passing
/// events to it, while also taking any add_update_monitor events and passing them to some remote
/// server(s).
///
/// Note that any updates to a channel's monitor *must* be applied to each instance of the
/// channel's monitor everywhere (including remote watchtowers) *before* this function returns. If
/// an update occurs and a remote watchtower is left with old state, it may broadcast transactions
/// which we have revoked, allowing our counterparty to claim all funds in the channel!
pub trait ManyChannelMonitor: Send + Sync {
        /// Adds or updates a monitor for the given `funding_txo`.
        ///
        /// Implementor must also ensure that the funding_txo outpoint is registered with any relevant
        /// ChainWatchInterfaces such that the provided monitor receives block_connected callbacks with
        /// any spends of it.
        fn add_update_monitor(&self, funding_txo: OutPoint, monitor: ChannelMonitor) -> Result<(), ChannelMonitorUpdateErr>;

        /// Used by ChannelManager to get list of HTLC resolved onchain and which needed to be updated
        /// with success or failure backward
        fn fetch_pending_htlc_updated(&self) -> Vec<HTLCUpdate>;
}

/// A simple implementation of a ManyChannelMonitor and ChainListener. Can be used to create a
/// watchtower or watch our own channels.
///
/// Note that you must provide your own key by which to refer to channels.
///
/// If you're accepting remote monitors (ie are implementing a watchtower), you must verify that
/// users cannot overwrite a given channel by providing a duplicate key. ie you should probably
/// index by a PublicKey which is required to sign any updates.
///
/// If you're using this for local monitoring of your own channels, you probably want to use
/// `OutPoint` as the key, which will give you a ManyChannelMonitor implementation.
pub struct SimpleManyChannelMonitor<Key> {
        #[cfg(test)] // Used in ChannelManager tests to manipulate channels directly
        pub monitors: Mutex<HashMap<Key, ChannelMonitor>>,
        #[cfg(not(test))]
        monitors: Mutex<HashMap<Key, ChannelMonitor>>,
        chain_monitor: Arc<ChainWatchInterface>,
        broadcaster: Arc<BroadcasterInterface>,
        pending_events: Mutex<Vec<events::Event>>,
        pending_htlc_updated: Mutex<HashMap<PaymentHash, Vec<(HTLCSource, Option<PaymentPreimage>)>>>,
        logger: Arc<Logger>,
}

impl<Key : Send + cmp::Eq + hash::Hash> ChainListener for SimpleManyChannelMonitor<Key> {
        fn block_connected(&self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], _indexes_of_txn_matched: &[u32]) {
                let block_hash = header.bitcoin_hash();
                let mut new_events: Vec<events::Event> = Vec::with_capacity(0);
                let mut htlc_updated_infos = Vec::new();
                {
                        let mut monitors = self.monitors.lock().unwrap();
                        for monitor in monitors.values_mut() {
                                let (txn_outputs, spendable_outputs, mut htlc_updated) = monitor.block_connected(txn_matched, height, &block_hash, &*self.broadcaster);
                                if spendable_outputs.len() > 0 {
                                        new_events.push(events::Event::SpendableOutputs {
                                                outputs: spendable_outputs,
                                        });
                                }

                                for (ref txid, ref outputs) in txn_outputs {
                                        for (idx, output) in outputs.iter().enumerate() {
                                                self.chain_monitor.install_watch_outpoint((txid.clone(), idx as u32), &output.script_pubkey);
                                        }
                                }
                                htlc_updated_infos.append(&mut htlc_updated);
                        }
                }
                {
                        // ChannelManager will just need to fetch pending_htlc_updated and pass state backward
                        let mut pending_htlc_updated = self.pending_htlc_updated.lock().unwrap();
                        for htlc in htlc_updated_infos.drain(..) {
                                match pending_htlc_updated.entry(htlc.2) {
                                        hash_map::Entry::Occupied(mut e) => {
                                                // In case of reorg we may have htlc outputs solved in a different way so
                                                // we prefer to keep claims but don't store duplicate updates for a given
                                                // (payment_hash, HTLCSource) pair.
                                                // TODO: Note that we currently don't really use this as ChannelManager
                                                // will fail/claim backwards after the first block. We really should delay
                                                // a few blocks before failing backwards (but can claim backwards
                                                // immediately) as long as we have a few blocks of headroom.
                                                let mut existing_claim = false;
                                                e.get_mut().retain(|htlc_data| {
                                                        if htlc.0 == htlc_data.0 {
                                                                if htlc_data.1.is_some() {
                                                                        existing_claim = true;
                                                                        true
                                                                } else { false }
                                                        } else { true }
                                                });
                                                if !existing_claim {
                                                        e.get_mut().push((htlc.0, htlc.1));
                                                }
                                        }
                                        hash_map::Entry::Vacant(e) => {
                                                e.insert(vec![(htlc.0, htlc.1)]);
                                        }
                                }
                        }
                }
                let mut pending_events = self.pending_events.lock().unwrap();
                pending_events.append(&mut new_events);
        }

        fn block_disconnected(&self, _: &BlockHeader) { }
}

impl<Key : Send + cmp::Eq + hash::Hash + 'static> SimpleManyChannelMonitor<Key> {
        /// Creates a new object which can be used to monitor several channels given the chain
        /// interface with which to register to receive notifications.
        pub fn new(chain_monitor: Arc<ChainWatchInterface>, broadcaster: Arc<BroadcasterInterface>, logger: Arc<Logger>) -> Arc<SimpleManyChannelMonitor<Key>> {
                let res = Arc::new(SimpleManyChannelMonitor {
                        monitors: Mutex::new(HashMap::new()),
                        chain_monitor,
                        broadcaster,
                        pending_events: Mutex::new(Vec::new()),
                        pending_htlc_updated: Mutex::new(HashMap::new()),
                        logger,
                });
                let weak_res = Arc::downgrade(&res);
                res.chain_monitor.register_listener(weak_res);
                res
        }

        /// Adds or updates the monitor which monitors the channel referred to by the given key.
        pub fn add_update_monitor_by_key(&self, key: Key, monitor: ChannelMonitor) -> Result<(), MonitorUpdateError> {
                let mut monitors = self.monitors.lock().unwrap();
                match monitors.get_mut(&key) {
                        Some(orig_monitor) => {
                                log_trace!(self, "Updating Channel Monitor for channel {}", log_funding_info!(monitor.key_storage));
                                return orig_monitor.insert_combine(monitor);
                        },
                        None => {}
                };
                match monitor.key_storage {
                        Storage::Local { ref funding_info, .. } => {
                                match funding_info {
                                        &None => {
                                                return Err(MonitorUpdateError("Try to update a useless monitor without funding_txo !"));
                                        },
                                        &Some((ref outpoint, ref script)) => {
                                                log_trace!(self, "Got new Channel Monitor for channel {}", log_bytes!(outpoint.to_channel_id()[..]));
                                                self.chain_monitor.install_watch_tx(&outpoint.txid, script);
                                                self.chain_monitor.install_watch_outpoint((outpoint.txid, outpoint.index as u32), script);
                                        },
                                }
                        },
                        Storage::Watchtower { .. } => {
                                self.chain_monitor.watch_all_txn();
                        }
                }
                monitors.insert(key, monitor);
                Ok(())
        }
}

impl ManyChannelMonitor for SimpleManyChannelMonitor<OutPoint> {
        fn add_update_monitor(&self, funding_txo: OutPoint, monitor: ChannelMonitor) -> Result<(), ChannelMonitorUpdateErr> {
                match self.add_update_monitor_by_key(funding_txo, monitor) {
                        Ok(_) => Ok(()),
                        Err(_) => Err(ChannelMonitorUpdateErr::PermanentFailure),
                }
        }

        fn fetch_pending_htlc_updated(&self) -> Vec<HTLCUpdate> {
                let mut updated = self.pending_htlc_updated.lock().unwrap();
                let mut pending_htlcs_updated = Vec::with_capacity(updated.len());
                for (k, v) in updated.drain() {
                        for htlc_data in v {
                                pending_htlcs_updated.push(HTLCUpdate {
                                        payment_hash: k,
                                        payment_preimage: htlc_data.1,
                                        source: htlc_data.0,
                                });
                        }
                }
                pending_htlcs_updated
        }
}

impl<Key : Send + cmp::Eq + hash::Hash> events::EventsProvider for SimpleManyChannelMonitor<Key> {
        fn get_and_clear_pending_events(&self) -> Vec<events::Event> {
                let mut pending_events = self.pending_events.lock().unwrap();
                let mut ret = Vec::new();
                mem::swap(&mut ret, &mut *pending_events);
                ret
        }
}

/// If an HTLC expires within this many blocks, don't try to claim it in a shared transaction,
/// instead claiming it in its own individual transaction.
const CLTV_SHARED_CLAIM_BUFFER: u32 = 12;
/// If an HTLC expires within this many blocks, force-close the channel to broadcast the
/// HTLC-Success transaction.
/// In other words, this is an upper bound on how many blocks we think it can take us to get a
/// transaction confirmed (and we use it in a few more, equivalent, places).
pub(crate) const CLTV_CLAIM_BUFFER: u32 = 6;
/// Number of blocks by which point we expect our counterparty to have seen new blocks on the
/// network and done a full update_fail_htlc/commitment_signed dance (+ we've updated all our
/// copies of ChannelMonitors, including watchtowers).
pub(crate) const HTLC_FAIL_TIMEOUT_BLOCKS: u32 = 3;
/// Number of blocks we wait on seeing a confirmed HTLC-Timeout or previous revoked commitment
/// transaction before we fail corresponding inbound HTLCs. This prevents us from failing backwards
/// and then getting a reorg resulting in us losing money.
//TODO: We currently don't actually use this...we should
pub(crate) const HTLC_FAIL_ANTI_REORG_DELAY: u32 = 6;

#[derive(Clone, PartialEq)]
enum Storage {
        Local {
                revocation_base_key: SecretKey,
                htlc_base_key: SecretKey,
                delayed_payment_base_key: SecretKey,
                payment_base_key: SecretKey,
                shutdown_pubkey: PublicKey,
                prev_latest_per_commitment_point: Option<PublicKey>,
                latest_per_commitment_point: Option<PublicKey>,
                funding_info: Option<(OutPoint, Script)>,
                current_remote_commitment_txid: Option<Sha256dHash>,
                prev_remote_commitment_txid: Option<Sha256dHash>,
        },
        Watchtower {
                revocation_base_key: PublicKey,
                htlc_base_key: PublicKey,
        }
}

#[derive(Clone, PartialEq)]
struct LocalSignedTx {
        /// txid of the transaction in tx, just used to make comparison faster
        txid: Sha256dHash,
        tx: Transaction,
        revocation_key: PublicKey,
        a_htlc_key: PublicKey,
        b_htlc_key: PublicKey,
        delayed_payment_key: PublicKey,
        feerate_per_kw: u64,
        htlc_outputs: Vec<(HTLCOutputInCommitment, Option<(Signature, Signature)>, Option<HTLCSource>)>,
}

const SERIALIZATION_VERSION: u8 = 1;
const MIN_SERIALIZATION_VERSION: u8 = 1;

/// A ChannelMonitor handles chain events (blocks connected and disconnected) and generates
/// on-chain transactions to ensure no loss of funds occurs.
///
/// You MUST ensure that no ChannelMonitors for a given channel anywhere contain out-of-date
/// information and are actively monitoring the chain.
#[derive(Clone)]
pub struct ChannelMonitor {
        commitment_transaction_number_obscure_factor: u64,

        key_storage: Storage,
        their_htlc_base_key: Option<PublicKey>,
        their_delayed_payment_base_key: Option<PublicKey>,
        // first is the idx of the first of the two revocation points
        their_cur_revocation_points: Option<(u64, PublicKey, Option<PublicKey>)>,

        our_to_self_delay: u16,
        their_to_self_delay: Option<u16>,

        old_secrets: [([u8; 32], u64); 49],
        remote_claimable_outpoints: HashMap<Sha256dHash, Vec<(HTLCOutputInCommitment, Option<Box<HTLCSource>>)>>,
        /// We cannot identify HTLC-Success or HTLC-Timeout transactions by themselves on the chain.
        /// Nor can we figure out their commitment numbers without the commitment transaction they are
        /// spending. Thus, in order to claim them via revocation key, we track all the remote
        /// commitment transactions which we find on-chain, mapping them to the commitment number which
        /// can be used to derive the revocation key and claim the transactions.
        remote_commitment_txn_on_chain: HashMap<Sha256dHash, (u64, Vec<Script>)>,
        /// Cache used to make pruning of payment_preimages faster.
        /// Maps payment_hash values to commitment numbers for remote transactions for non-revoked
        /// remote transactions (ie should remain pretty small).
        /// Serialized to disk but should generally not be sent to Watchtowers.
        remote_hash_commitment_number: HashMap<PaymentHash, u64>,

        // We store two local commitment transactions to avoid any race conditions where we may update
        // some monitors (potentially on watchtowers) but then fail to update others, resulting in the
        // various monitors for one channel being out of sync, and us broadcasting a local
        // transaction for which we have deleted claim information on some watchtowers.
        prev_local_signed_commitment_tx: Option<LocalSignedTx>,
        current_local_signed_commitment_tx: Option<LocalSignedTx>,

        // Used just for ChannelManager to make sure it has the latest channel data during
        // deserialization
        current_remote_commitment_number: u64,

        payment_preimages: HashMap<PaymentHash, PaymentPreimage>,

        destination_script: Script,

        // We simply modify last_block_hash in Channel's block_connected so that serialization is
        // consistent but hopefully the users' copy handles block_connected in a consistent way.
        // (we do *not*, however, update them in insert_combine to ensure any local user copies keep
        // their last_block_hash from its state and not based on updated copies that didn't run through
        // the full block_connected).
        pub(crate) last_block_hash: Sha256dHash,
        secp_ctx: Secp256k1<secp256k1::All>, //TODO: dedup this a bit...
        logger: Arc<Logger>,
}

#[cfg(any(test, feature = "fuzztarget"))]
/// Used only in testing and fuzztarget to check serialization roundtrips don't change the
/// underlying object
impl PartialEq for ChannelMonitor {
        fn eq(&self, other: &Self) -> bool {
                if self.commitment_transaction_number_obscure_factor != other.commitment_transaction_number_obscure_factor ||
                        self.key_storage != other.key_storage ||
                        self.their_htlc_base_key != other.their_htlc_base_key ||
                        self.their_delayed_payment_base_key != other.their_delayed_payment_base_key ||
                        self.their_cur_revocation_points != other.their_cur_revocation_points ||
                        self.our_to_self_delay != other.our_to_self_delay ||
                        self.their_to_self_delay != other.their_to_self_delay ||
                        self.remote_claimable_outpoints != other.remote_claimable_outpoints ||
                        self.remote_commitment_txn_on_chain != other.remote_commitment_txn_on_chain ||
                        self.remote_hash_commitment_number != other.remote_hash_commitment_number ||
                        self.prev_local_signed_commitment_tx != other.prev_local_signed_commitment_tx ||
                        self.current_remote_commitment_number != other.current_remote_commitment_number ||
                        self.current_local_signed_commitment_tx != other.current_local_signed_commitment_tx ||
                        self.payment_preimages != other.payment_preimages ||
                        self.destination_script != other.destination_script
                {
                        false
                } else {
                        for (&(ref secret, ref idx), &(ref o_secret, ref o_idx)) in self.old_secrets.iter().zip(other.old_secrets.iter()) {
                                if secret != o_secret || idx != o_idx {
                                        return false
                                }
                        }
                        true
                }
        }
}

impl ChannelMonitor {
        pub(super) fn new(revocation_base_key: &SecretKey, delayed_payment_base_key: &SecretKey, htlc_base_key: &SecretKey, payment_base_key: &SecretKey, shutdown_pubkey: &PublicKey, our_to_self_delay: u16, destination_script: Script, logger: Arc<Logger>) -> ChannelMonitor {
                ChannelMonitor {
                        commitment_transaction_number_obscure_factor: 0,

                        key_storage: Storage::Local {
                                revocation_base_key: revocation_base_key.clone(),
                                htlc_base_key: htlc_base_key.clone(),
                                delayed_payment_base_key: delayed_payment_base_key.clone(),
                                payment_base_key: payment_base_key.clone(),
                                shutdown_pubkey: shutdown_pubkey.clone(),
                                prev_latest_per_commitment_point: None,
                                latest_per_commitment_point: None,
                                funding_info: None,
                                current_remote_commitment_txid: None,
                                prev_remote_commitment_txid: None,
                        },
                        their_htlc_base_key: None,
                        their_delayed_payment_base_key: None,
                        their_cur_revocation_points: None,

                        our_to_self_delay: our_to_self_delay,
                        their_to_self_delay: None,

                        old_secrets: [([0; 32], 1 << 48); 49],
                        remote_claimable_outpoints: HashMap::new(),
                        remote_commitment_txn_on_chain: HashMap::new(),
                        remote_hash_commitment_number: HashMap::new(),

                        prev_local_signed_commitment_tx: None,
                        current_local_signed_commitment_tx: None,
                        current_remote_commitment_number: 1 << 48,

                        payment_preimages: HashMap::new(),
                        destination_script: destination_script,

                        last_block_hash: Default::default(),
                        secp_ctx: Secp256k1::new(),
                        logger,
                }
        }

        #[inline]
        fn place_secret(idx: u64) -> u8 {
                for i in 0..48 {
                        if idx & (1 << i) == (1 << i) {
                                return i
                        }
                }
                48
        }

        #[inline]
        fn derive_secret(secret: [u8; 32], bits: u8, idx: u64) -> [u8; 32] {
                let mut res: [u8; 32] = secret;
                for i in 0..bits {
                        let bitpos = bits - 1 - i;
                        if idx & (1 << bitpos) == (1 << bitpos) {
                                res[(bitpos / 8) as usize] ^= 1 << (bitpos & 7);
                                res = Sha256::hash(&res).into_inner();
                        }
                }
                res
        }

        /// Inserts a revocation secret into this channel monitor. Prunes old preimages if neither
        /// needed by local commitment transactions HTCLs nor by remote ones. Unless we haven't already seen remote
        /// commitment transaction's secret, they are de facto pruned (we can use revocation key).
        pub(super) fn provide_secret(&mut self, idx: u64, secret: [u8; 32]) -> Result<(), MonitorUpdateError> {
                let pos = ChannelMonitor::place_secret(idx);
                for i in 0..pos {
                        let (old_secret, old_idx) = self.old_secrets[i as usize];
                        if ChannelMonitor::derive_secret(secret, pos, old_idx) != old_secret {
                                return Err(MonitorUpdateError("Previous secret did not match new one"));
                        }
                }
                if self.get_min_seen_secret() <= idx {
                        return Ok(());
                }
                self.old_secrets[pos as usize] = (secret, idx);

                // Prune HTLCs from the previous remote commitment tx so we don't generate failure/fulfill
                // events for now-revoked/fulfilled HTLCs.
                // TODO: We should probably consider whether we're really getting the next secret here.
                if let Storage::Local { ref mut prev_remote_commitment_txid, .. } = self.key_storage {
                        if let Some(txid) = prev_remote_commitment_txid.take() {
                                for &mut (_, ref mut source) in self.remote_claimable_outpoints.get_mut(&txid).unwrap() {
                                        *source = None;
                                }
                        }
                }

                if !self.payment_preimages.is_empty() {
                        let local_signed_commitment_tx = self.current_local_signed_commitment_tx.as_ref().expect("Channel needs at least an initial commitment tx !");
                        let prev_local_signed_commitment_tx = self.prev_local_signed_commitment_tx.as_ref();
                        let min_idx = self.get_min_seen_secret();
                        let remote_hash_commitment_number = &mut self.remote_hash_commitment_number;

                        self.payment_preimages.retain(|&k, _| {
                                for &(ref htlc, _, _) in &local_signed_commitment_tx.htlc_outputs {
                                        if k == htlc.payment_hash {
                                                return true
                                        }
                                }
                                if let Some(prev_local_commitment_tx) = prev_local_signed_commitment_tx {
                                        for &(ref htlc, _, _) in prev_local_commitment_tx.htlc_outputs.iter() {
                                                if k == htlc.payment_hash {
                                                        return true
                                                }
                                        }
                                }
                                let contains = if let Some(cn) = remote_hash_commitment_number.get(&k) {
                                        if *cn < min_idx {
                                                return true
                                        }
                                        true
                                } else { false };
                                if contains {
                                        remote_hash_commitment_number.remove(&k);
                                }
                                false
                        });
                }

                Ok(())
        }

        /// Informs this monitor of the latest remote (ie non-broadcastable) commitment transaction.
        /// The monitor watches for it to be broadcasted and then uses the HTLC information (and
        /// possibly future revocation/preimage information) to claim outputs where possible.
        /// We cache also the mapping hash:commitment number to lighten pruning of old preimages by watchtowers.
        pub(super) fn provide_latest_remote_commitment_tx_info(&mut self, unsigned_commitment_tx: &Transaction, htlc_outputs: Vec<(HTLCOutputInCommitment, Option<Box<HTLCSource>>)>, commitment_number: u64, their_revocation_point: PublicKey) {
                // TODO: Encrypt the htlc_outputs data with the single-hash of the commitment transaction
                // so that a remote monitor doesn't learn anything unless there is a malicious close.
                // (only maybe, sadly we cant do the same for local info, as we need to be aware of
                // timeouts)
                for &(ref htlc, _) in &htlc_outputs {
                        self.remote_hash_commitment_number.insert(htlc.payment_hash, commitment_number);
                }

                let new_txid = unsigned_commitment_tx.txid();
                log_trace!(self, "Tracking new remote commitment transaction with txid {} at commitment number {} with {} HTLC outputs", new_txid, commitment_number, htlc_outputs.len());
                log_trace!(self, "New potential remote commitment transaction: {}", encode::serialize_hex(unsigned_commitment_tx));
                if let Storage::Local { ref mut current_remote_commitment_txid, ref mut prev_remote_commitment_txid, .. } = self.key_storage {
                        *prev_remote_commitment_txid = current_remote_commitment_txid.take();
                        *current_remote_commitment_txid = Some(new_txid);
                }
                self.remote_claimable_outpoints.insert(new_txid, htlc_outputs);
                self.current_remote_commitment_number = commitment_number;
                //TODO: Merge this into the other per-remote-transaction output storage stuff
                match self.their_cur_revocation_points {
                        Some(old_points) => {
                                if old_points.0 == commitment_number + 1 {
                                        self.their_cur_revocation_points = Some((old_points.0, old_points.1, Some(their_revocation_point)));
                                } else if old_points.0 == commitment_number + 2 {
                                        if let Some(old_second_point) = old_points.2 {
                                                self.their_cur_revocation_points = Some((old_points.0 - 1, old_second_point, Some(their_revocation_point)));
                                        } else {
                                                self.their_cur_revocation_points = Some((commitment_number, their_revocation_point, None));
                                        }
                                } else {
                                        self.their_cur_revocation_points = Some((commitment_number, their_revocation_point, None));
                                }
                        },
                        None => {
                                self.their_cur_revocation_points = Some((commitment_number, their_revocation_point, None));
                        }
                }
        }

        /// Informs this monitor of the latest local (ie broadcastable) commitment transaction. The
        /// monitor watches for timeouts and may broadcast it if we approach such a timeout. Thus, it
        /// is important that any clones of this channel monitor (including remote clones) by kept
        /// up-to-date as our local commitment transaction is updated.
        /// Panics if set_their_to_self_delay has never been called.
        /// Also update Storage with latest local per_commitment_point to derive local_delayedkey in
        /// case of onchain HTLC tx
        pub(super) fn provide_latest_local_commitment_tx_info(&mut self, signed_commitment_tx: Transaction, local_keys: chan_utils::TxCreationKeys, feerate_per_kw: u64, htlc_outputs: Vec<(HTLCOutputInCommitment, Option<(Signature, Signature)>, Option<HTLCSource>)>) {
                assert!(self.their_to_self_delay.is_some());
                self.prev_local_signed_commitment_tx = self.current_local_signed_commitment_tx.take();
                self.current_local_signed_commitment_tx = Some(LocalSignedTx {
                        txid: signed_commitment_tx.txid(),
                        tx: signed_commitment_tx,
                        revocation_key: local_keys.revocation_key,
                        a_htlc_key: local_keys.a_htlc_key,
                        b_htlc_key: local_keys.b_htlc_key,
                        delayed_payment_key: local_keys.a_delayed_payment_key,
                        feerate_per_kw,
                        htlc_outputs,
                });

                if let Storage::Local { ref mut latest_per_commitment_point, .. } = self.key_storage {
                        *latest_per_commitment_point = Some(local_keys.per_commitment_point);
                } else {
                        panic!("Channel somehow ended up with its internal ChannelMonitor being in Watchtower mode?");
                }
        }

        /// Provides a payment_hash->payment_preimage mapping. Will be automatically pruned when all
        /// commitment_tx_infos which contain the payment hash have been revoked.
        pub(super) fn provide_payment_preimage(&mut self, payment_hash: &PaymentHash, payment_preimage: &PaymentPreimage) {
                self.payment_preimages.insert(payment_hash.clone(), payment_preimage.clone());
        }

        /// Combines this ChannelMonitor with the information contained in the other ChannelMonitor.
        /// After a successful call this ChannelMonitor is up-to-date and is safe to use to monitor the
        /// chain for new blocks/transactions.
        pub fn insert_combine(&mut self, mut other: ChannelMonitor) -> Result<(), MonitorUpdateError> {
                match self.key_storage {
                        Storage::Local { ref funding_info, .. } => {
                                if funding_info.is_none() { return Err(MonitorUpdateError("Try to combine a Local monitor without funding_info")); }
                                let our_funding_info = funding_info;
                                if let Storage::Local { ref funding_info, .. } = other.key_storage {
                                        if funding_info.is_none() { return Err(MonitorUpdateError("Try to combine a Local monitor without funding_info")); }
                                        // We should be able to compare the entire funding_txo, but in fuzztarget it's trivially
                                        // easy to collide the funding_txo hash and have a different scriptPubKey.
                                        if funding_info.as_ref().unwrap().0 != our_funding_info.as_ref().unwrap().0 {
                                                return Err(MonitorUpdateError("Funding transaction outputs are not identical!"));
                                        }
                                } else {
                                        return Err(MonitorUpdateError("Try to combine a Local monitor with a Watchtower one !"));
                                }
                        },
                        Storage::Watchtower { .. } => {
                                if let Storage::Watchtower { .. } = other.key_storage {
                                        unimplemented!();
                                } else {
                                        return Err(MonitorUpdateError("Try to combine a Watchtower monitor with a Local one !"));
                                }
                        },
                }
                let other_min_secret = other.get_min_seen_secret();
                let our_min_secret = self.get_min_seen_secret();
                if our_min_secret > other_min_secret {
                        self.provide_secret(other_min_secret, other.get_secret(other_min_secret).unwrap())?;
                }
                if let Some(ref local_tx) = self.current_local_signed_commitment_tx {
                        if let Some(ref other_local_tx) = other.current_local_signed_commitment_tx {
                                let our_commitment_number = 0xffffffffffff - ((((local_tx.tx.input[0].sequence as u64 & 0xffffff) << 3*8) | (local_tx.tx.lock_time as u64 & 0xffffff)) ^ self.commitment_transaction_number_obscure_factor);
                                let other_commitment_number = 0xffffffffffff - ((((other_local_tx.tx.input[0].sequence as u64 & 0xffffff) << 3*8) | (other_local_tx.tx.lock_time as u64 & 0xffffff)) ^ other.commitment_transaction_number_obscure_factor);
                                if our_commitment_number >= other_commitment_number {
                                        self.key_storage = other.key_storage;
                                }
                        }
                }
                // TODO: We should use current_remote_commitment_number and the commitment number out of
                // local transactions to decide how to merge
                if our_min_secret >= other_min_secret {
                        self.their_cur_revocation_points = other.their_cur_revocation_points;
                        for (txid, htlcs) in other.remote_claimable_outpoints.drain() {
                                self.remote_claimable_outpoints.insert(txid, htlcs);
                        }
                        if let Some(local_tx) = other.prev_local_signed_commitment_tx {
                                self.prev_local_signed_commitment_tx = Some(local_tx);
                        }
                        if let Some(local_tx) = other.current_local_signed_commitment_tx {
                                self.current_local_signed_commitment_tx = Some(local_tx);
                        }
                        self.payment_preimages = other.payment_preimages;
                }

                self.current_remote_commitment_number = cmp::min(self.current_remote_commitment_number, other.current_remote_commitment_number);
                Ok(())
        }

        /// Panics if commitment_transaction_number_obscure_factor doesn't fit in 48 bits
        pub(super) fn set_commitment_obscure_factor(&mut self, commitment_transaction_number_obscure_factor: u64) {
                assert!(commitment_transaction_number_obscure_factor < (1 << 48));
                self.commitment_transaction_number_obscure_factor = commitment_transaction_number_obscure_factor;
        }

        /// Allows this monitor to scan only for transactions which are applicable. Note that this is
        /// optional, without it this monitor cannot be used in an SPV client, but you may wish to
        /// avoid this (or call unset_funding_info) on a monitor you wish to send to a watchtower as it
        /// provides slightly better privacy.
        /// It's the responsibility of the caller to register outpoint and script with passing the former
        /// value as key to add_update_monitor.
        pub(super) fn set_funding_info(&mut self, new_funding_info: (OutPoint, Script)) {
                match self.key_storage {
                        Storage::Local { ref mut funding_info, .. } => {
                                *funding_info = Some(new_funding_info);
                        },
                        Storage::Watchtower { .. } => {
                                panic!("Channel somehow ended up with its internal ChannelMonitor being in Watchtower mode?");
                        }
                }
        }

        /// We log these base keys at channel opening to being able to rebuild redeemscript in case of leaked revoked commit tx
        pub(super) fn set_their_base_keys(&mut self, their_htlc_base_key: &PublicKey, their_delayed_payment_base_key: &PublicKey) {
                self.their_htlc_base_key = Some(their_htlc_base_key.clone());
                self.their_delayed_payment_base_key = Some(their_delayed_payment_base_key.clone());
        }

        pub(super) fn set_their_to_self_delay(&mut self, their_to_self_delay: u16) {
                self.their_to_self_delay = Some(their_to_self_delay);
        }

        pub(super) fn unset_funding_info(&mut self) {
                match self.key_storage {
                        Storage::Local { ref mut funding_info, .. } => {
                                *funding_info = None;
                        },
                        Storage::Watchtower { .. } => {
                                panic!("Channel somehow ended up with its internal ChannelMonitor being in Watchtower mode?");
                        },
                }
        }

        /// Gets the funding transaction outpoint of the channel this ChannelMonitor is monitoring for.
        pub fn get_funding_txo(&self) -> Option<OutPoint> {
                match self.key_storage {
                        Storage::Local { ref funding_info, .. } => {
                                match funding_info {
                                        &Some((outpoint, _)) => Some(outpoint),
                                        &None => None
                                }
                        },
                        Storage::Watchtower { .. } => {
                                return None;
                        }
                }
        }

        /// Gets the sets of all outpoints which this ChannelMonitor expects to hear about spends of.
        /// Generally useful when deserializing as during normal operation the return values of
        /// block_connected are sufficient to ensure all relevant outpoints are being monitored (note
        /// that the get_funding_txo outpoint and transaction must also be monitored for!).
        pub fn get_monitored_outpoints(&self) -> Vec<(Sha256dHash, u32, &Script)> {
                let mut res = Vec::with_capacity(self.remote_commitment_txn_on_chain.len() * 2);
                for (ref txid, &(_, ref outputs)) in self.remote_commitment_txn_on_chain.iter() {
                        for (idx, output) in outputs.iter().enumerate() {
                                res.push(((*txid).clone(), idx as u32, output));
                        }
                }
                res
        }

        /// Serializes into a vec, with various modes for the exposed pub fns
        fn write<W: Writer>(&self, writer: &mut W, for_local_storage: bool) -> Result<(), ::std::io::Error> {
                //TODO: We still write out all the serialization here manually instead of using the fancy
                //serialization framework we have, we should migrate things over to it.
                writer.write_all(&[SERIALIZATION_VERSION; 1])?;
                writer.write_all(&[MIN_SERIALIZATION_VERSION; 1])?;

                // Set in initial Channel-object creation, so should always be set by now:
                U48(self.commitment_transaction_number_obscure_factor).write(writer)?;

                macro_rules! write_option {
                        ($thing: expr) => {
                                match $thing {
                                        &Some(ref t) => {
                                                1u8.write(writer)?;
                                                t.write(writer)?;
                                        },
                                        &None => 0u8.write(writer)?,
                                }
                        }
                }

                match self.key_storage {
                        Storage::Local { ref revocation_base_key, ref htlc_base_key, ref delayed_payment_base_key, ref payment_base_key, ref shutdown_pubkey, ref prev_latest_per_commitment_point, ref latest_per_commitment_point, ref funding_info, ref current_remote_commitment_txid, ref prev_remote_commitment_txid } => {
                                writer.write_all(&[0; 1])?;
                                writer.write_all(&revocation_base_key[..])?;
                                writer.write_all(&htlc_base_key[..])?;
                                writer.write_all(&delayed_payment_base_key[..])?;
                                writer.write_all(&payment_base_key[..])?;
                                writer.write_all(&shutdown_pubkey.serialize())?;
                                if let Some(ref prev_latest_per_commitment_point) = *prev_latest_per_commitment_point {
                                        writer.write_all(&[1; 1])?;
                                        writer.write_all(&prev_latest_per_commitment_point.serialize())?;
                                } else {
                                        writer.write_all(&[0; 1])?;
                                }
                                if let Some(ref latest_per_commitment_point) = *latest_per_commitment_point {
                                        writer.write_all(&[1; 1])?;
                                        writer.write_all(&latest_per_commitment_point.serialize())?;
                                } else {
                                        writer.write_all(&[0; 1])?;
                                }
                                match funding_info  {
                                        &Some((ref outpoint, ref script)) => {
                                                writer.write_all(&outpoint.txid[..])?;
                                                writer.write_all(&byte_utils::be16_to_array(outpoint.index))?;
                                                script.write(writer)?;
                                        },
                                        &None => {
                                                debug_assert!(false, "Try to serialize a useless Local monitor !");
                                        },
                                }
                                write_option!(current_remote_commitment_txid);
                                write_option!(prev_remote_commitment_txid);
                        },
                        Storage::Watchtower { .. } => unimplemented!(),
                }

                writer.write_all(&self.their_htlc_base_key.as_ref().unwrap().serialize())?;
                writer.write_all(&self.their_delayed_payment_base_key.as_ref().unwrap().serialize())?;

                match self.their_cur_revocation_points {
                        Some((idx, pubkey, second_option)) => {
                                writer.write_all(&byte_utils::be48_to_array(idx))?;
                                writer.write_all(&pubkey.serialize())?;
                                match second_option {
                                        Some(second_pubkey) => {
                                                writer.write_all(&second_pubkey.serialize())?;
                                        },
                                        None => {
                                                writer.write_all(&[0; 33])?;
                                        },
                                }
                        },
                        None => {
                                writer.write_all(&byte_utils::be48_to_array(0))?;
                        },
                }

                writer.write_all(&byte_utils::be16_to_array(self.our_to_self_delay))?;
                writer.write_all(&byte_utils::be16_to_array(self.their_to_self_delay.unwrap()))?;

                for &(ref secret, ref idx) in self.old_secrets.iter() {
                        writer.write_all(secret)?;
                        writer.write_all(&byte_utils::be64_to_array(*idx))?;
                }

                macro_rules! serialize_htlc_in_commitment {
                        ($htlc_output: expr) => {
                                writer.write_all(&[$htlc_output.offered as u8; 1])?;
                                writer.write_all(&byte_utils::be64_to_array($htlc_output.amount_msat))?;
                                writer.write_all(&byte_utils::be32_to_array($htlc_output.cltv_expiry))?;
                                writer.write_all(&$htlc_output.payment_hash.0[..])?;
                                write_option!(&$htlc_output.transaction_output_index);
                        }
                }

                writer.write_all(&byte_utils::be64_to_array(self.remote_claimable_outpoints.len() as u64))?;
                for (ref txid, ref htlc_infos) in self.remote_claimable_outpoints.iter() {
                        writer.write_all(&txid[..])?;
                        writer.write_all(&byte_utils::be64_to_array(htlc_infos.len() as u64))?;
                        for &(ref htlc_output, ref htlc_source) in htlc_infos.iter() {
                                serialize_htlc_in_commitment!(htlc_output);
                                write_option!(htlc_source);
                        }
                }

                writer.write_all(&byte_utils::be64_to_array(self.remote_commitment_txn_on_chain.len() as u64))?;
                for (ref txid, &(commitment_number, ref txouts)) in self.remote_commitment_txn_on_chain.iter() {
                        writer.write_all(&txid[..])?;
                        writer.write_all(&byte_utils::be48_to_array(commitment_number))?;
                        (txouts.len() as u64).write(writer)?;
                        for script in txouts.iter() {
                                script.write(writer)?;
                        }
                }

                if for_local_storage {
                        writer.write_all(&byte_utils::be64_to_array(self.remote_hash_commitment_number.len() as u64))?;
                        for (ref payment_hash, commitment_number) in self.remote_hash_commitment_number.iter() {
                                writer.write_all(&payment_hash.0[..])?;
                                writer.write_all(&byte_utils::be48_to_array(*commitment_number))?;
                        }
                } else {
                        writer.write_all(&byte_utils::be64_to_array(0))?;
                }

                macro_rules! serialize_local_tx {
                        ($local_tx: expr) => {
                                if let Err(e) = $local_tx.tx.consensus_encode(&mut WriterWriteAdaptor(writer)) {
                                        match e {
                                                encode::Error::Io(e) => return Err(e),
                                                _ => panic!("local tx must have been well-formed!"),
                                        }
                                }

                                writer.write_all(&$local_tx.revocation_key.serialize())?;
                                writer.write_all(&$local_tx.a_htlc_key.serialize())?;
                                writer.write_all(&$local_tx.b_htlc_key.serialize())?;
                                writer.write_all(&$local_tx.delayed_payment_key.serialize())?;

                                writer.write_all(&byte_utils::be64_to_array($local_tx.feerate_per_kw))?;
                                writer.write_all(&byte_utils::be64_to_array($local_tx.htlc_outputs.len() as u64))?;
                                for &(ref htlc_output, ref sigs, ref htlc_source) in $local_tx.htlc_outputs.iter() {
                                        serialize_htlc_in_commitment!(htlc_output);
                                        if let &Some((ref their_sig, ref our_sig)) = sigs {
                                                1u8.write(writer)?;
                                                writer.write_all(&their_sig.serialize_compact())?;
                                                writer.write_all(&our_sig.serialize_compact())?;
                                        } else {
                                                0u8.write(writer)?;
                                        }
                                        write_option!(htlc_source);
                                }
                        }
                }

                if let Some(ref prev_local_tx) = self.prev_local_signed_commitment_tx {
                        writer.write_all(&[1; 1])?;
                        serialize_local_tx!(prev_local_tx);
                } else {
                        writer.write_all(&[0; 1])?;
                }

                if let Some(ref cur_local_tx) = self.current_local_signed_commitment_tx {
                        writer.write_all(&[1; 1])?;
                        serialize_local_tx!(cur_local_tx);
                } else {
                        writer.write_all(&[0; 1])?;
                }

                if for_local_storage {
                        writer.write_all(&byte_utils::be48_to_array(self.current_remote_commitment_number))?;
                } else {
                        writer.write_all(&byte_utils::be48_to_array(0))?;
                }

                writer.write_all(&byte_utils::be64_to_array(self.payment_preimages.len() as u64))?;
                for payment_preimage in self.payment_preimages.values() {
                        writer.write_all(&payment_preimage.0[..])?;
                }

                self.last_block_hash.write(writer)?;
                self.destination_script.write(writer)?;

                Ok(())
        }

        /// Writes this monitor into the given writer, suitable for writing to disk.
        ///
        /// Note that the deserializer is only implemented for (Sha256dHash, ChannelMonitor), which
        /// tells you the last block hash which was block_connect()ed. You MUST rescan any blocks along
        /// the "reorg path" (ie not just starting at the same height but starting at the highest
        /// common block that appears on your best chain as well as on the chain which contains the
        /// last block hash returned) upon deserializing the object!
        pub fn write_for_disk<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                self.write(writer, true)
        }

        /// Encodes this monitor into the given writer, suitable for sending to a remote watchtower
        ///
        /// Note that the deserializer is only implemented for (Sha256dHash, ChannelMonitor), which
        /// tells you the last block hash which was block_connect()ed. You MUST rescan any blocks along
        /// the "reorg path" (ie not just starting at the same height but starting at the highest
        /// common block that appears on your best chain as well as on the chain which contains the
        /// last block hash returned) upon deserializing the object!
        pub fn write_for_watchtower<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                self.write(writer, false)
        }

        /// Can only fail if idx is < get_min_seen_secret
        pub(super) fn get_secret(&self, idx: u64) -> Option<[u8; 32]> {
                for i in 0..self.old_secrets.len() {
                        if (idx & (!((1 << i) - 1))) == self.old_secrets[i].1 {
                                return Some(ChannelMonitor::derive_secret(self.old_secrets[i].0, i as u8, idx))
                        }
                }
                assert!(idx < self.get_min_seen_secret());
                None
        }

        pub(super) fn get_min_seen_secret(&self) -> u64 {
                //TODO This can be optimized?
                let mut min = 1 << 48;
                for &(_, idx) in self.old_secrets.iter() {
                        if idx < min {
                                min = idx;
                        }
                }
                min
        }

        pub(super) fn get_cur_remote_commitment_number(&self) -> u64 {
                self.current_remote_commitment_number
        }

        pub(super) fn get_cur_local_commitment_number(&self) -> u64 {
                if let &Some(ref local_tx) = &self.current_local_signed_commitment_tx {
                        0xffff_ffff_ffff - ((((local_tx.tx.input[0].sequence as u64 & 0xffffff) << 3*8) | (local_tx.tx.lock_time as u64 & 0xffffff)) ^ self.commitment_transaction_number_obscure_factor)
                } else { 0xffff_ffff_ffff }
        }

        /// Attempts to claim a remote commitment transaction's outputs using the revocation key and
        /// data in remote_claimable_outpoints. Will directly claim any HTLC outputs which expire at a
        /// height > height + CLTV_SHARED_CLAIM_BUFFER. In any case, will install monitoring for
        /// HTLC-Success/HTLC-Timeout transactions.
        /// Return updates for HTLC pending in the channel and failed automatically by the broadcast of
        /// revoked remote commitment tx
        fn check_spend_remote_transaction(&mut self, tx: &Transaction, height: u32) -> (Vec<Transaction>, (Sha256dHash, Vec<TxOut>), Vec<SpendableOutputDescriptor>, Vec<(HTLCSource, Option<PaymentPreimage>, PaymentHash)>)  {
                // Most secp and related errors trying to create keys means we have no hope of constructing
                // a spend transaction...so we return no transactions to broadcast
                let mut txn_to_broadcast = Vec::new();
                let mut watch_outputs = Vec::new();
                let mut spendable_outputs = Vec::new();
                let mut htlc_updated = Vec::new();

                let commitment_txid = tx.txid(); //TODO: This is gonna be a performance bottleneck for watchtowers!
                let per_commitment_option = self.remote_claimable_outpoints.get(&commitment_txid);

                macro_rules! ignore_error {
                        ( $thing : expr ) => {
                                match $thing {
                                        Ok(a) => a,
                                        Err(_) => return (txn_to_broadcast, (commitment_txid, watch_outputs), spendable_outputs, htlc_updated)
                                }
                        };
                }

                let commitment_number = 0xffffffffffff - ((((tx.input[0].sequence as u64 & 0xffffff) << 3*8) | (tx.lock_time as u64 & 0xffffff)) ^ self.commitment_transaction_number_obscure_factor);
                if commitment_number >= self.get_min_seen_secret() {
                        let secret = self.get_secret(commitment_number).unwrap();
                        let per_commitment_key = ignore_error!(SecretKey::from_slice(&secret));
                        let (revocation_pubkey, b_htlc_key, local_payment_key) = match self.key_storage {
                                Storage::Local { ref revocation_base_key, ref htlc_base_key, ref payment_base_key, .. } => {
                                        let per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key);
                                        (ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, &per_commitment_point, &PublicKey::from_secret_key(&self.secp_ctx, &revocation_base_key))),
                                        ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, &per_commitment_point, &PublicKey::from_secret_key(&self.secp_ctx, &htlc_base_key))),
                                        Some(ignore_error!(chan_utils::derive_private_key(&self.secp_ctx, &per_commitment_point, &payment_base_key))))
                                },
                                Storage::Watchtower { ref revocation_base_key, ref htlc_base_key, .. } => {
                                        let per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key);
                                        (ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, &per_commitment_point, &revocation_base_key)),
                                        ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, &per_commitment_point, &htlc_base_key)),
                                        None)
                                },
                        };
                        let delayed_key = ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, &PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key), &self.their_delayed_payment_base_key.unwrap()));
                        let a_htlc_key = match self.their_htlc_base_key {
                                None => return (txn_to_broadcast, (commitment_txid, watch_outputs), spendable_outputs, htlc_updated),
                                Some(their_htlc_base_key) => ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, &PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key), &their_htlc_base_key)),
                        };

                        let revokeable_redeemscript = chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.our_to_self_delay, &delayed_key);
                        let revokeable_p2wsh = revokeable_redeemscript.to_v0_p2wsh();

                        let local_payment_p2wpkh = if let Some(payment_key) = local_payment_key {
                                // Note that the Network here is ignored as we immediately drop the address for the
                                // script_pubkey version.
                                let payment_hash160 = Hash160::hash(&PublicKey::from_secret_key(&self.secp_ctx, &payment_key).serialize());
                                Some(Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&payment_hash160[..]).into_script())
                        } else { None };

                        let mut total_value = 0;
                        let mut values = Vec::new();
                        let mut inputs = Vec::new();
                        let mut htlc_idxs = Vec::new();

                        for (idx, outp) in tx.output.iter().enumerate() {
                                if outp.script_pubkey == revokeable_p2wsh {
                                        inputs.push(TxIn {
                                                previous_output: BitcoinOutPoint {
                                                        txid: commitment_txid,
                                                        vout: idx as u32,
                                                },
                                                script_sig: Script::new(),
                                                sequence: 0xfffffffd,
                                                witness: Vec::new(),
                                        });
                                        htlc_idxs.push(None);
                                        values.push(outp.value);
                                        total_value += outp.value;
                                } else if Some(&outp.script_pubkey) == local_payment_p2wpkh.as_ref() {
                                        spendable_outputs.push(SpendableOutputDescriptor::DynamicOutputP2WPKH {
                                                outpoint: BitcoinOutPoint { txid: commitment_txid, vout: idx as u32 },
                                                key: local_payment_key.unwrap(),
                                                output: outp.clone(),
                                        });
                                }
                        }

                        macro_rules! sign_input {
                                ($sighash_parts: expr, $input: expr, $htlc_idx: expr, $amount: expr) => {
                                        {
                                                let (sig, redeemscript) = match self.key_storage {
                                                        Storage::Local { ref revocation_base_key, .. } => {
                                                                let redeemscript = if $htlc_idx.is_none() { revokeable_redeemscript.clone() } else {
                                                                        let htlc = &per_commitment_option.unwrap()[$htlc_idx.unwrap()].0;
                                                                        chan_utils::get_htlc_redeemscript_with_explicit_keys(htlc, &a_htlc_key, &b_htlc_key, &revocation_pubkey)
                                                                };
                                                                let sighash = hash_to_message!(&$sighash_parts.sighash_all(&$input, &redeemscript, $amount)[..]);
                                                                let revocation_key = ignore_error!(chan_utils::derive_private_revocation_key(&self.secp_ctx, &per_commitment_key, &revocation_base_key));
                                                                (self.secp_ctx.sign(&sighash, &revocation_key), redeemscript)
                                                        },
                                                        Storage::Watchtower { .. } => {
                                                                unimplemented!();
                                                        }
                                                };
                                                $input.witness.push(sig.serialize_der().to_vec());
                                                $input.witness[0].push(SigHashType::All as u8);
                                                if $htlc_idx.is_none() {
                                                        $input.witness.push(vec!(1));
                                                } else {
                                                        $input.witness.push(revocation_pubkey.serialize().to_vec());
                                                }
                                                $input.witness.push(redeemscript.into_bytes());
                                        }
                                }
                        }

                        if let Some(ref per_commitment_data) = per_commitment_option {
                                inputs.reserve_exact(per_commitment_data.len());

                                for (idx, &(ref htlc, _)) in per_commitment_data.iter().enumerate() {
                                        if let Some(transaction_output_index) = htlc.transaction_output_index {
                                                let expected_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &a_htlc_key, &b_htlc_key, &revocation_pubkey);
                                                if transaction_output_index as usize >= tx.output.len() ||
                                                                tx.output[transaction_output_index as usize].value != htlc.amount_msat / 1000 ||
                                                                tx.output[transaction_output_index as usize].script_pubkey != expected_script.to_v0_p2wsh() {
                                                        return (txn_to_broadcast, (commitment_txid, watch_outputs), spendable_outputs, htlc_updated); // Corrupted per_commitment_data, fuck this user
                                                }
                                                let input = TxIn {
                                                        previous_output: BitcoinOutPoint {
                                                                txid: commitment_txid,
                                                                vout: transaction_output_index,
                                                        },
                                                        script_sig: Script::new(),
                                                        sequence: 0xfffffffd,
                                                        witness: Vec::new(),
                                                };
                                                if htlc.cltv_expiry > height + CLTV_SHARED_CLAIM_BUFFER {
                                                        inputs.push(input);
                                                        htlc_idxs.push(Some(idx));
                                                        values.push(tx.output[transaction_output_index as usize].value);
                                                        total_value += htlc.amount_msat / 1000;
                                                } else {
                                                        let mut single_htlc_tx = Transaction {
                                                                version: 2,
                                                                lock_time: 0,
                                                                input: vec![input],
                                                                output: vec!(TxOut {
                                                                        script_pubkey: self.destination_script.clone(),
                                                                        value: htlc.amount_msat / 1000, //TODO: - fee
                                                                }),
                                                        };
                                                        let sighash_parts = bip143::SighashComponents::new(&single_htlc_tx);
                                                        sign_input!(sighash_parts, single_htlc_tx.input[0], Some(idx), htlc.amount_msat / 1000);
                                                        txn_to_broadcast.push(single_htlc_tx);
                                                }
                                        }
                                }
                        }

                        if !inputs.is_empty() || !txn_to_broadcast.is_empty() || per_commitment_option.is_some() { // ie we're confident this is actually ours
                                // We're definitely a remote commitment transaction!
                                log_trace!(self, "Got broadcast of revoked remote commitment transaction, generating general spend tx with {} inputs and {} other txn to broadcast", inputs.len(), txn_to_broadcast.len());
                                watch_outputs.append(&mut tx.output.clone());
                                self.remote_commitment_txn_on_chain.insert(commitment_txid, (commitment_number, tx.output.iter().map(|output| { output.script_pubkey.clone() }).collect()));

                                // TODO: We really should only fail backwards after our revocation claims have been
                                // confirmed, but we also need to do more other tracking of in-flight pre-confirm
                                // on-chain claims, so we can do that at the same time.
                                macro_rules! check_htlc_fails {
                                        ($txid: expr, $commitment_tx: expr) => {
                                                if let Some(ref outpoints) = self.remote_claimable_outpoints.get($txid) {
                                                        for &(ref htlc, ref source_option) in outpoints.iter() {
                                                                if let &Some(ref source) = source_option {
                                                                        log_trace!(self, "Failing HTLC with payment_hash {} from {} remote commitment tx due to broadcast of revoked remote commitment transaction", log_bytes!(htlc.payment_hash.0), $commitment_tx);
                                                                        htlc_updated.push(((**source).clone(), None, htlc.payment_hash.clone()));
                                                                }
                                                        }
                                                }
                                        }
                                }
                                if let Storage::Local { ref current_remote_commitment_txid, ref prev_remote_commitment_txid, .. } = self.key_storage {
                                        if let &Some(ref txid) = current_remote_commitment_txid {
                                                check_htlc_fails!(txid, "current");
                                        }
                                        if let &Some(ref txid) = prev_remote_commitment_txid {
                                                check_htlc_fails!(txid, "remote");
                                        }
                                }
                                // No need to check local commitment txn, symmetric HTLCSource must be present as per-htlc data on remote commitment tx
                        }
                        if inputs.is_empty() { return (txn_to_broadcast, (commitment_txid, watch_outputs), spendable_outputs, htlc_updated); } // Nothing to be done...probably a false positive/local tx

                        let outputs = vec!(TxOut {
                                script_pubkey: self.destination_script.clone(),
                                value: total_value, //TODO: - fee
                        });
                        let mut spend_tx = Transaction {
                                version: 2,
                                lock_time: 0,
                                input: inputs,
                                output: outputs,
                        };

                        let mut values_drain = values.drain(..);
                        let sighash_parts = bip143::SighashComponents::new(&spend_tx);

                        for (input, htlc_idx) in spend_tx.input.iter_mut().zip(htlc_idxs.iter()) {
                                let value = values_drain.next().unwrap();
                                sign_input!(sighash_parts, input, htlc_idx, value);
                        }

                        spendable_outputs.push(SpendableOutputDescriptor::StaticOutput {
                                outpoint: BitcoinOutPoint { txid: spend_tx.txid(), vout: 0 },
                                output: spend_tx.output[0].clone(),
                        });
                        txn_to_broadcast.push(spend_tx);
                } else if let Some(per_commitment_data) = per_commitment_option {
                        // While this isn't useful yet, there is a potential race where if a counterparty
                        // revokes a state at the same time as the commitment transaction for that state is
                        // confirmed, and the watchtower receives the block before the user, the user could
                        // upload a new ChannelMonitor with the revocation secret but the watchtower has
                        // already processed the block, resulting in the remote_commitment_txn_on_chain entry
                        // not being generated by the above conditional. Thus, to be safe, we go ahead and
                        // insert it here.
                        watch_outputs.append(&mut tx.output.clone());
                        self.remote_commitment_txn_on_chain.insert(commitment_txid, (commitment_number, tx.output.iter().map(|output| { output.script_pubkey.clone() }).collect()));

                        log_trace!(self, "Got broadcast of non-revoked remote commitment transaction {}", commitment_txid);

                        // TODO: We really should only fail backwards after our revocation claims have been
                        // confirmed, but we also need to do more other tracking of in-flight pre-confirm
                        // on-chain claims, so we can do that at the same time.
                        macro_rules! check_htlc_fails {
                                ($txid: expr, $commitment_tx: expr, $id: tt) => {
                                        if let Some(ref latest_outpoints) = self.remote_claimable_outpoints.get($txid) {
                                                $id: for &(ref htlc, ref source_option) in latest_outpoints.iter() {
                                                        if let &Some(ref source) = source_option {
                                                                // Check if the HTLC is present in the commitment transaction that was
                                                                // broadcast, but not if it was below the dust limit, which we should
                                                                // fail backwards immediately as there is no way for us to learn the
                                                                // payment_preimage.
                                                                // Note that if the dust limit were allowed to change between
                                                                // commitment transactions we'd want to be check whether *any*
                                                                // broadcastable commitment transaction has the HTLC in it, but it
                                                                // cannot currently change after channel initialization, so we don't
                                                                // need to here.
                                                                for &(ref broadcast_htlc, ref broadcast_source) in per_commitment_data.iter() {
                                                                        if broadcast_htlc.transaction_output_index.is_some() && Some(source) == broadcast_source.as_ref() {
                                                                                continue $id;
                                                                        }
                                                                }
                                                                log_trace!(self, "Failing HTLC with payment_hash {} from {} remote commitment tx due to broadcast of remote commitment transaction", log_bytes!(htlc.payment_hash.0), $commitment_tx);
                                                                htlc_updated.push(((**source).clone(), None, htlc.payment_hash.clone()));
                                                        }
                                                }
                                        }
                                }
                        }
                        if let Storage::Local { ref current_remote_commitment_txid, ref prev_remote_commitment_txid, .. } = self.key_storage {
                                if let &Some(ref txid) = current_remote_commitment_txid {
                                        check_htlc_fails!(txid, "current", 'current_loop);
                                }
                                if let &Some(ref txid) = prev_remote_commitment_txid {
                                        check_htlc_fails!(txid, "previous", 'prev_loop);
                                }
                        }

                        if let Some(revocation_points) = self.their_cur_revocation_points {
                                let revocation_point_option =
                                        if revocation_points.0 == commitment_number { Some(&revocation_points.1) }
                                        else if let Some(point) = revocation_points.2.as_ref() {
                                                if revocation_points.0 == commitment_number + 1 { Some(point) } else { None }
                                        } else { None };
                                if let Some(revocation_point) = revocation_point_option {
                                        let (revocation_pubkey, b_htlc_key) = match self.key_storage {
                                                Storage::Local { ref revocation_base_key, ref htlc_base_key, .. } => {
                                                        (ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, revocation_point, &PublicKey::from_secret_key(&self.secp_ctx, &revocation_base_key))),
                                                        ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, revocation_point, &PublicKey::from_secret_key(&self.secp_ctx, &htlc_base_key))))
                                                },
                                                Storage::Watchtower { ref revocation_base_key, ref htlc_base_key, .. } => {
                                                        (ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, revocation_point, &revocation_base_key)),
                                                        ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, revocation_point, &htlc_base_key)))
                                                },
                                        };
                                        let a_htlc_key = match self.their_htlc_base_key {
                                                None => return (txn_to_broadcast, (commitment_txid, watch_outputs), spendable_outputs, htlc_updated),
                                                Some(their_htlc_base_key) => ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, revocation_point, &their_htlc_base_key)),
                                        };

                                        for (idx, outp) in tx.output.iter().enumerate() {
                                                if outp.script_pubkey.is_v0_p2wpkh() {
                                                        match self.key_storage {
                                                                Storage::Local { ref payment_base_key, .. } => {
                                                                        if let Ok(local_key) = chan_utils::derive_private_key(&self.secp_ctx, &revocation_point, &payment_base_key) {
                                                                                spendable_outputs.push(SpendableOutputDescriptor::DynamicOutputP2WPKH {
                                                                                        outpoint: BitcoinOutPoint { txid: commitment_txid, vout: idx as u32 },
                                                                                        key: local_key,
                                                                                        output: outp.clone(),
                                                                                });
                                                                        }
                                                                },
                                                                Storage::Watchtower { .. } => {}
                                                        }
                                                        break; // Only to_remote ouput is claimable
                                                }
                                        }

                                        let mut total_value = 0;
                                        let mut values = Vec::new();
                                        let mut inputs = Vec::new();

                                        macro_rules! sign_input {
                                                ($sighash_parts: expr, $input: expr, $amount: expr, $preimage: expr) => {
                                                        {
                                                                let (sig, redeemscript) = match self.key_storage {
                                                                        Storage::Local { ref htlc_base_key, .. } => {
                                                                                let htlc = &per_commitment_option.unwrap()[$input.sequence as usize].0;
                                                                                let redeemscript = chan_utils::get_htlc_redeemscript_with_explicit_keys(htlc, &a_htlc_key, &b_htlc_key, &revocation_pubkey);
                                                                                let sighash = hash_to_message!(&$sighash_parts.sighash_all(&$input, &redeemscript, $amount)[..]);
                                                                                let htlc_key = ignore_error!(chan_utils::derive_private_key(&self.secp_ctx, revocation_point, &htlc_base_key));
                                                                                (self.secp_ctx.sign(&sighash, &htlc_key), redeemscript)
                                                                        },
                                                                        Storage::Watchtower { .. } => {
                                                                                unimplemented!();
                                                                        }
                                                                };
                                                                $input.witness.push(sig.serialize_der().to_vec());
                                                                $input.witness[0].push(SigHashType::All as u8);
                                                                $input.witness.push($preimage);
                                                                $input.witness.push(redeemscript.into_bytes());
                                                        }
                                                }
                                        }

                                        for (idx, &(ref htlc, _)) in per_commitment_data.iter().enumerate() {
                                                if let Some(transaction_output_index) = htlc.transaction_output_index {
                                                        let expected_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &a_htlc_key, &b_htlc_key, &revocation_pubkey);
                                                        if transaction_output_index as usize >= tx.output.len() ||
                                                                        tx.output[transaction_output_index as usize].value != htlc.amount_msat / 1000 ||
                                                                        tx.output[transaction_output_index as usize].script_pubkey != expected_script.to_v0_p2wsh() {
                                                                return (txn_to_broadcast, (commitment_txid, watch_outputs), spendable_outputs, htlc_updated); // Corrupted per_commitment_data, fuck this user
                                                        }
                                                        if let Some(payment_preimage) = self.payment_preimages.get(&htlc.payment_hash) {
                                                                let input = TxIn {
                                                                        previous_output: BitcoinOutPoint {
                                                                                txid: commitment_txid,
                                                                                vout: transaction_output_index,
                                                                        },
                                                                        script_sig: Script::new(),
                                                                        sequence: idx as u32, // reset to 0xfffffffd in sign_input
                                                                        witness: Vec::new(),
                                                                };
                                                                if htlc.cltv_expiry > height + CLTV_SHARED_CLAIM_BUFFER {
                                                                        inputs.push(input);
                                                                        values.push((tx.output[transaction_output_index as usize].value, payment_preimage));
                                                                        total_value += htlc.amount_msat / 1000;
                                                                } else {
                                                                        let mut single_htlc_tx = Transaction {
                                                                                version: 2,
                                                                                lock_time: 0,
                                                                                input: vec![input],
                                                                                output: vec!(TxOut {
                                                                                        script_pubkey: self.destination_script.clone(),
                                                                                        value: htlc.amount_msat / 1000, //TODO: - fee
                                                                                }),
                                                                        };
                                                                        let sighash_parts = bip143::SighashComponents::new(&single_htlc_tx);
                                                                        sign_input!(sighash_parts, single_htlc_tx.input[0], htlc.amount_msat / 1000, payment_preimage.0.to_vec());
                                                                        spendable_outputs.push(SpendableOutputDescriptor::StaticOutput {
                                                                                outpoint: BitcoinOutPoint { txid: single_htlc_tx.txid(), vout: 0 },
                                                                                output: single_htlc_tx.output[0].clone(),
                                                                        });
                                                                        txn_to_broadcast.push(single_htlc_tx);
                                                                }
                                                        }
                                                        if !htlc.offered {
                                                                // TODO: If the HTLC has already expired, potentially merge it with the
                                                                // rest of the claim transaction, as above.
                                                                let input = TxIn {
                                                                        previous_output: BitcoinOutPoint {
                                                                                txid: commitment_txid,
                                                                                vout: transaction_output_index,
                                                                        },
                                                                        script_sig: Script::new(),
                                                                        sequence: idx as u32,
                                                                        witness: Vec::new(),
                                                                };
                                                                let mut timeout_tx = Transaction {
                                                                        version: 2,
                                                                        lock_time: htlc.cltv_expiry,
                                                                        input: vec![input],
                                                                        output: vec!(TxOut {
                                                                                script_pubkey: self.destination_script.clone(),
                                                                                value: htlc.amount_msat / 1000,
                                                                        }),
                                                                };
                                                                let sighash_parts = bip143::SighashComponents::new(&timeout_tx);
                                                                sign_input!(sighash_parts, timeout_tx.input[0], htlc.amount_msat / 1000, vec![0]);
                                                                txn_to_broadcast.push(timeout_tx);
                                                        }
                                                }
                                        }

                                        if inputs.is_empty() { return (txn_to_broadcast, (commitment_txid, watch_outputs), spendable_outputs, htlc_updated); } // Nothing to be done...probably a false positive/local tx

                                        let outputs = vec!(TxOut {
                                                script_pubkey: self.destination_script.clone(),
                                                value: total_value, //TODO: - fee
                                        });
                                        let mut spend_tx = Transaction {
                                                version: 2,
                                                lock_time: 0,
                                                input: inputs,
                                                output: outputs,
                                        };

                                        let mut values_drain = values.drain(..);
                                        let sighash_parts = bip143::SighashComponents::new(&spend_tx);

                                        for input in spend_tx.input.iter_mut() {
                                                let value = values_drain.next().unwrap();
                                                sign_input!(sighash_parts, input, value.0, (value.1).0.to_vec());
                                        }

                                        spendable_outputs.push(SpendableOutputDescriptor::StaticOutput {
                                                outpoint: BitcoinOutPoint { txid: spend_tx.txid(), vout: 0 },
                                                output: spend_tx.output[0].clone(),
                                        });
                                        txn_to_broadcast.push(spend_tx);
                                }
                        }
                }

                (txn_to_broadcast, (commitment_txid, watch_outputs), spendable_outputs, htlc_updated)
        }

        /// Attempts to claim a remote HTLC-Success/HTLC-Timeout's outputs using the revocation key
        fn check_spend_remote_htlc(&self, tx: &Transaction, commitment_number: u64) -> (Option<Transaction>, Option<SpendableOutputDescriptor>) {
                if tx.input.len() != 1 || tx.output.len() != 1 {
                        return (None, None)
                }

                macro_rules! ignore_error {
                        ( $thing : expr ) => {
                                match $thing {
                                        Ok(a) => a,
                                        Err(_) => return (None, None)
                                }
                        };
                }

                let secret = if let Some(secret) = self.get_secret(commitment_number) { secret } else { return (None, None); };
                let per_commitment_key = ignore_error!(SecretKey::from_slice(&secret));
                let per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key);
                let revocation_pubkey = match self.key_storage {
                        Storage::Local { ref revocation_base_key, .. } => {
                                ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, &per_commitment_point, &PublicKey::from_secret_key(&self.secp_ctx, &revocation_base_key)))
                        },
                        Storage::Watchtower { ref revocation_base_key, .. } => {
                                ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, &per_commitment_point, &revocation_base_key))
                        },
                };
                let delayed_key = match self.their_delayed_payment_base_key {
                        None => return (None, None),
                        Some(their_delayed_payment_base_key) => ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, &per_commitment_point, &their_delayed_payment_base_key)),
                };
                let redeemscript = chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.their_to_self_delay.unwrap(), &delayed_key);
                let revokeable_p2wsh = redeemscript.to_v0_p2wsh();
                let htlc_txid = tx.txid(); //TODO: This is gonna be a performance bottleneck for watchtowers!

                let mut inputs = Vec::new();
                let mut amount = 0;

                if tx.output[0].script_pubkey == revokeable_p2wsh { //HTLC transactions have one txin, one txout
                        inputs.push(TxIn {
                                previous_output: BitcoinOutPoint {
                                        txid: htlc_txid,
                                        vout: 0,
                                },
                                script_sig: Script::new(),
                                sequence: 0xfffffffd,
                                witness: Vec::new(),
                        });
                        amount = tx.output[0].value;
                }

                if !inputs.is_empty() {
                        let outputs = vec!(TxOut {
                                script_pubkey: self.destination_script.clone(),
                                value: amount, //TODO: - fee
                        });

                        let mut spend_tx = Transaction {
                                version: 2,
                                lock_time: 0,
                                input: inputs,
                                output: outputs,
                        };

                        let sighash_parts = bip143::SighashComponents::new(&spend_tx);

                        let sig = match self.key_storage {
                                Storage::Local { ref revocation_base_key, .. } => {
                                        let sighash = hash_to_message!(&sighash_parts.sighash_all(&spend_tx.input[0], &redeemscript, amount)[..]);
                                        let revocation_key = ignore_error!(chan_utils::derive_private_revocation_key(&self.secp_ctx, &per_commitment_key, &revocation_base_key));
                                        self.secp_ctx.sign(&sighash, &revocation_key)
                                }
                                Storage::Watchtower { .. } => {
                                        unimplemented!();
                                }
                        };
                        spend_tx.input[0].witness.push(sig.serialize_der().to_vec());
                        spend_tx.input[0].witness[0].push(SigHashType::All as u8);
                        spend_tx.input[0].witness.push(vec!(1));
                        spend_tx.input[0].witness.push(redeemscript.into_bytes());

                        let outpoint = BitcoinOutPoint { txid: spend_tx.txid(), vout: 0 };
                        let output = spend_tx.output[0].clone();
                        (Some(spend_tx), Some(SpendableOutputDescriptor::StaticOutput { outpoint, output }))
                } else { (None, None) }
        }

        fn broadcast_by_local_state(&self, local_tx: &LocalSignedTx, per_commitment_point: &Option<PublicKey>, delayed_payment_base_key: &Option<SecretKey>) -> (Vec<Transaction>, Vec<SpendableOutputDescriptor>, Vec<TxOut>) {
                let mut res = Vec::with_capacity(local_tx.htlc_outputs.len());
                let mut spendable_outputs = Vec::with_capacity(local_tx.htlc_outputs.len());
                let mut watch_outputs = Vec::with_capacity(local_tx.htlc_outputs.len());

                macro_rules! add_dynamic_output {
                        ($father_tx: expr, $vout: expr) => {
                                if let Some(ref per_commitment_point) = *per_commitment_point {
                                        if let Some(ref delayed_payment_base_key) = *delayed_payment_base_key {
                                                if let Ok(local_delayedkey) = chan_utils::derive_private_key(&self.secp_ctx, per_commitment_point, delayed_payment_base_key) {
                                                        spendable_outputs.push(SpendableOutputDescriptor::DynamicOutputP2WSH {
                                                                outpoint: BitcoinOutPoint { txid: $father_tx.txid(), vout: $vout },
                                                                key: local_delayedkey,
                                                                witness_script: chan_utils::get_revokeable_redeemscript(&local_tx.revocation_key, self.our_to_self_delay, &local_tx.delayed_payment_key),
                                                                to_self_delay: self.our_to_self_delay,
                                                                output: $father_tx.output[$vout as usize].clone(),
                                                        });
                                                }
                                        }
                                }
                        }
                }


                let redeemscript = chan_utils::get_revokeable_redeemscript(&local_tx.revocation_key, self.their_to_self_delay.unwrap(), &local_tx.delayed_payment_key);
                let revokeable_p2wsh = redeemscript.to_v0_p2wsh();
                for (idx, output) in local_tx.tx.output.iter().enumerate() {
                        if output.script_pubkey == revokeable_p2wsh {
                                add_dynamic_output!(local_tx.tx, idx as u32);
                                break;
                        }
                }

                for &(ref htlc, ref sigs, _) in local_tx.htlc_outputs.iter() {
                        if let Some(transaction_output_index) = htlc.transaction_output_index {
                                if let &Some((ref their_sig, ref our_sig)) = sigs {
                                        if htlc.offered {
                                                log_trace!(self, "Broadcasting HTLC-Timeout transaction against local commitment transactions");
                                                let mut htlc_timeout_tx = chan_utils::build_htlc_transaction(&local_tx.txid, local_tx.feerate_per_kw, self.their_to_self_delay.unwrap(), htlc, &local_tx.delayed_payment_key, &local_tx.revocation_key);

                                                htlc_timeout_tx.input[0].witness.push(Vec::new()); // First is the multisig dummy

                                                htlc_timeout_tx.input[0].witness.push(their_sig.serialize_der().to_vec());
                                                htlc_timeout_tx.input[0].witness[1].push(SigHashType::All as u8);
                                                htlc_timeout_tx.input[0].witness.push(our_sig.serialize_der().to_vec());
                                                htlc_timeout_tx.input[0].witness[2].push(SigHashType::All as u8);

                                                htlc_timeout_tx.input[0].witness.push(Vec::new());
                                                htlc_timeout_tx.input[0].witness.push(chan_utils::get_htlc_redeemscript_with_explicit_keys(htlc, &local_tx.a_htlc_key, &local_tx.b_htlc_key, &local_tx.revocation_key).into_bytes());

                                                add_dynamic_output!(htlc_timeout_tx, 0);
                                                res.push(htlc_timeout_tx);
                                        } else {
                                                if let Some(payment_preimage) = self.payment_preimages.get(&htlc.payment_hash) {
                                                        log_trace!(self, "Broadcasting HTLC-Success transaction against local commitment transactions");
                                                        let mut htlc_success_tx = chan_utils::build_htlc_transaction(&local_tx.txid, local_tx.feerate_per_kw, self.their_to_self_delay.unwrap(), htlc, &local_tx.delayed_payment_key, &local_tx.revocation_key);

                                                        htlc_success_tx.input[0].witness.push(Vec::new()); // First is the multisig dummy

                                                        htlc_success_tx.input[0].witness.push(their_sig.serialize_der().to_vec());
                                                        htlc_success_tx.input[0].witness[1].push(SigHashType::All as u8);
                                                        htlc_success_tx.input[0].witness.push(our_sig.serialize_der().to_vec());
                                                        htlc_success_tx.input[0].witness[2].push(SigHashType::All as u8);

                                                        htlc_success_tx.input[0].witness.push(payment_preimage.0.to_vec());
                                                        htlc_success_tx.input[0].witness.push(chan_utils::get_htlc_redeemscript_with_explicit_keys(htlc, &local_tx.a_htlc_key, &local_tx.b_htlc_key, &local_tx.revocation_key).into_bytes());

                                                        add_dynamic_output!(htlc_success_tx, 0);
                                                        res.push(htlc_success_tx);
                                                }
                                        }
                                        watch_outputs.push(local_tx.tx.output[transaction_output_index as usize].clone());
                                } else { panic!("Should have sigs for non-dust local tx outputs!") }
                        }
                }

                (res, spendable_outputs, watch_outputs)
        }

        /// Attempts to claim any claimable HTLCs in a commitment transaction which was not (yet)
        /// revoked using data in local_claimable_outpoints.
        /// Should not be used if check_spend_revoked_transaction succeeds.
        fn check_spend_local_transaction(&self, tx: &Transaction, _height: u32) -> (Vec<Transaction>, Vec<SpendableOutputDescriptor>, (Sha256dHash, Vec<TxOut>)) {
                let commitment_txid = tx.txid();
                // TODO: If we find a match here we need to fail back HTLCs that weren't included in the
                // broadcast commitment transaction, either because they didn't meet dust or because they
                // weren't yet included in our commitment transaction(s).
                if let &Some(ref local_tx) = &self.current_local_signed_commitment_tx {
                        if local_tx.txid == commitment_txid {
                                log_trace!(self, "Got latest local commitment tx broadcast, searching for available HTLCs to claim");
                                match self.key_storage {
                                        Storage::Local { ref delayed_payment_base_key, ref latest_per_commitment_point, .. } => {
                                                let (local_txn, spendable_outputs, watch_outputs) = self.broadcast_by_local_state(local_tx, latest_per_commitment_point, &Some(*delayed_payment_base_key));
                                                return (local_txn, spendable_outputs, (commitment_txid, watch_outputs));
                                        },
                                        Storage::Watchtower { .. } => {
                                                let (local_txn, spendable_outputs, watch_outputs) = self.broadcast_by_local_state(local_tx, &None, &None);
                                                return (local_txn, spendable_outputs, (commitment_txid, watch_outputs));
                                        }
                                }
                        }
                }
                if let &Some(ref local_tx) = &self.prev_local_signed_commitment_tx {
                        if local_tx.txid == commitment_txid {
                                log_trace!(self, "Got previous local commitment tx broadcast, searching for available HTLCs to claim");
                                match self.key_storage {
                                        Storage::Local { ref delayed_payment_base_key, ref prev_latest_per_commitment_point, .. } => {
                                                let (local_txn, spendable_outputs, watch_outputs) = self.broadcast_by_local_state(local_tx, prev_latest_per_commitment_point, &Some(*delayed_payment_base_key));
                                                return (local_txn, spendable_outputs, (commitment_txid, watch_outputs));
                                        },
                                        Storage::Watchtower { .. } => {
                                                let (local_txn, spendable_outputs, watch_outputs) = self.broadcast_by_local_state(local_tx, &None, &None);
                                                return (local_txn, spendable_outputs, (commitment_txid, watch_outputs));
                                        }
                                }
                        }
                }
                (Vec::new(), Vec::new(), (commitment_txid, Vec::new()))
        }

        /// Generate a spendable output event when closing_transaction get registered onchain.
        fn check_spend_closing_transaction(&self, tx: &Transaction) -> Option<SpendableOutputDescriptor> {
                if tx.input[0].sequence == 0xFFFFFFFF && !tx.input[0].witness.is_empty() && tx.input[0].witness.last().unwrap().len() == 71 {
                        match self.key_storage {
                                Storage::Local { ref shutdown_pubkey, .. } =>  {
                                        let our_channel_close_key_hash = Hash160::hash(&shutdown_pubkey.serialize());
                                        let shutdown_script = Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&our_channel_close_key_hash[..]).into_script();
                                        for (idx, output) in tx.output.iter().enumerate() {
                                                if shutdown_script == output.script_pubkey {
                                                        return Some(SpendableOutputDescriptor::StaticOutput {
                                                                outpoint: BitcoinOutPoint { txid: tx.txid(), vout: idx as u32 },
                                                                output: output.clone(),
                                                        });
                                                }
                                        }
                                }
                                Storage::Watchtower { .. } => {
                                        //TODO: we need to ensure an offline client will generate the event when it
                                        // comes back online after only the watchtower saw the transaction
                                }
                        }
                }
                None
        }

        /// Used by ChannelManager deserialization to broadcast the latest local state if it's copy of
        /// the Channel was out-of-date.
        pub(super) fn get_latest_local_commitment_txn(&self) -> Vec<Transaction> {
                if let &Some(ref local_tx) = &self.current_local_signed_commitment_tx {
                        let mut res = vec![local_tx.tx.clone()];
                        match self.key_storage {
                                Storage::Local { ref delayed_payment_base_key, ref prev_latest_per_commitment_point, .. } => {
                                        res.append(&mut self.broadcast_by_local_state(local_tx, prev_latest_per_commitment_point, &Some(*delayed_payment_base_key)).0);
                                },
                                _ => panic!("Can only broadcast by local channelmonitor"),
                        };
                        res
                } else {
                        Vec::new()
                }
        }

        fn block_connected(&mut self, txn_matched: &[&Transaction], height: u32, block_hash: &Sha256dHash, broadcaster: &BroadcasterInterface)-> (Vec<(Sha256dHash, Vec<TxOut>)>, Vec<SpendableOutputDescriptor>, Vec<(HTLCSource, Option<PaymentPreimage>, PaymentHash)>) {
                let mut watch_outputs = Vec::new();
                let mut spendable_outputs = Vec::new();
                let mut htlc_updated = Vec::new();
                for tx in txn_matched {
                        if tx.input.len() == 1 {
                                // Assuming our keys were not leaked (in which case we're screwed no matter what),
                                // commitment transactions and HTLC transactions will all only ever have one input,
                                // which is an easy way to filter out any potential non-matching txn for lazy
                                // filters.
                                let prevout = &tx.input[0].previous_output;
                                let mut txn: Vec<Transaction> = Vec::new();
                                let funding_txo = match self.key_storage {
                                        Storage::Local { ref funding_info, .. } => {
                                                funding_info.clone()
                                        }
                                        Storage::Watchtower { .. } => {
                                                unimplemented!();
                                        }
                                };
                                if funding_txo.is_none() || (prevout.txid == funding_txo.as_ref().unwrap().0.txid && prevout.vout == funding_txo.as_ref().unwrap().0.index as u32) {
                                        let (remote_txn, new_outputs, mut spendable_output, mut updated) = self.check_spend_remote_transaction(tx, height);
                                        txn = remote_txn;
                                        spendable_outputs.append(&mut spendable_output);
                                        if !new_outputs.1.is_empty() {
                                                watch_outputs.push(new_outputs);
                                        }
                                        if txn.is_empty() {
                                                let (local_txn, mut spendable_output, new_outputs) = self.check_spend_local_transaction(tx, height);
                                                spendable_outputs.append(&mut spendable_output);
                                                txn = local_txn;
                                                if !new_outputs.1.is_empty() {
                                                        watch_outputs.push(new_outputs);
                                                }
                                        }
                                        if !funding_txo.is_none() && txn.is_empty() {
                                                if let Some(spendable_output) = self.check_spend_closing_transaction(tx) {
                                                        spendable_outputs.push(spendable_output);
                                                }
                                        }
                                        if updated.len() > 0 {
                                                htlc_updated.append(&mut updated);
                                        }
                                } else {
                                        if let Some(&(commitment_number, _)) = self.remote_commitment_txn_on_chain.get(&prevout.txid) {
                                                let (tx, spendable_output) = self.check_spend_remote_htlc(tx, commitment_number);
                                                if let Some(tx) = tx {
                                                        txn.push(tx);
                                                }
                                                if let Some(spendable_output) = spendable_output {
                                                        spendable_outputs.push(spendable_output);
                                                }
                                        }
                                }
                                for tx in txn.iter() {
                                        broadcaster.broadcast_transaction(tx);
                                }
                        }
                        // While all commitment/HTLC-Success/HTLC-Timeout transactions have one input, HTLCs
                        // can also be resolved in a few other ways which can have more than one output. Thus,
                        // we call is_resolving_htlc_output here outside of the tx.input.len() == 1 check.
                        let mut updated = self.is_resolving_htlc_output(tx);
                        if updated.len() > 0 {
                                htlc_updated.append(&mut updated);
                        }
                }
                if let Some(ref cur_local_tx) = self.current_local_signed_commitment_tx {
                        if self.would_broadcast_at_height(height) {
                                broadcaster.broadcast_transaction(&cur_local_tx.tx);
                                match self.key_storage {
                                        Storage::Local { ref delayed_payment_base_key, ref latest_per_commitment_point, .. } => {
                                                let (txs, mut spendable_output, new_outputs) = self.broadcast_by_local_state(&cur_local_tx, latest_per_commitment_point, &Some(*delayed_payment_base_key));
                                                spendable_outputs.append(&mut spendable_output);
                                                if !new_outputs.is_empty() {
                                                        watch_outputs.push((cur_local_tx.txid.clone(), new_outputs));
                                                }
                                                for tx in txs {
                                                        broadcaster.broadcast_transaction(&tx);
                                                }
                                        },
                                        Storage::Watchtower { .. } => {
                                                let (txs, mut spendable_output, new_outputs) = self.broadcast_by_local_state(&cur_local_tx, &None, &None);
                                                spendable_outputs.append(&mut spendable_output);
                                                if !new_outputs.is_empty() {
                                                        watch_outputs.push((cur_local_tx.txid.clone(), new_outputs));
                                                }
                                                for tx in txs {
                                                        broadcaster.broadcast_transaction(&tx);
                                                }
                                        }
                                }
                        }
                }
                self.last_block_hash = block_hash.clone();
                (watch_outputs, spendable_outputs, htlc_updated)
        }

        pub(super) fn would_broadcast_at_height(&self, height: u32) -> bool {
                // We need to consider all HTLCs which are:
                //  * in any unrevoked remote commitment transaction, as they could broadcast said
                //    transactions and we'd end up in a race, or
                //  * are in our latest local commitment transaction, as this is the thing we will
                //    broadcast if we go on-chain.
                // Note that we consider HTLCs which were below dust threshold here - while they don't
                // strictly imply that we need to fail the channel, we need to go ahead and fail them back
                // to the source, and if we don't fail the channel we will have to ensure that the next
                // updates that peer sends us are update_fails, failing the channel if not. It's probably
                // easier to just fail the channel as this case should be rare enough anyway.
                macro_rules! scan_commitment {
                        ($htlcs: expr, $local_tx: expr) => {
                                for ref htlc in $htlcs {
                                        // For inbound HTLCs which we know the preimage for, we have to ensure we hit the
                                        // chain with enough room to claim the HTLC without our counterparty being able to
                                        // time out the HTLC first.
                                        // For outbound HTLCs which our counterparty hasn't failed/claimed, our primary
                                        // concern is being able to claim the corresponding inbound HTLC (on another
                                        // channel) before it expires. In fact, we don't even really care if our
                                        // counterparty here claims such an outbound HTLC after it expired as long as we
                                        // can still claim the corresponding HTLC. Thus, to avoid needlessly hitting the
                                        // chain when our counterparty is waiting for expiration to off-chain fail an HTLC
                                        // we give ourselves a few blocks of headroom after expiration before going
                                        // on-chain for an expired HTLC.
                                        // Note that, to avoid a potential attack whereby a node delays claiming an HTLC
                                        // from us until we've reached the point where we go on-chain with the
                                        // corresponding inbound HTLC, we must ensure that outbound HTLCs go on chain at
                                        // least CLTV_CLAIM_BUFFER blocks prior to the inbound HTLC.
                                        //  aka outbound_cltv + HTLC_FAIL_TIMEOUT_BLOCKS == height - CLTV_CLAIM_BUFFER
                                        //      inbound_cltv == height + CLTV_CLAIM_BUFFER
                                        //      outbound_cltv + HTLC_FAIL_TIMEOUT_BLOCKS + CLTV_CLAIM_BUFFER <= inbound_cltv - CLTV_CLAIM_BUFFER
                                        //      HTLC_FAIL_TIMEOUT_BLOCKS + 2*CLTV_CLAIM_BUFFER <= inbound_cltv - outbound_cltv
                                        //      CLTV_EXPIRY_DELTA <= inbound_cltv - outbound_cltv (by check in ChannelManager::decode_update_add_htlc_onion)
                                        //      HTLC_FAIL_TIMEOUT_BLOCKS + 2*CLTV_CLAIM_BUFFER <= CLTV_EXPIRY_DELTA
                                        //  The final, above, condition is checked for statically in channelmanager
                                        //  with CHECK_CLTV_EXPIRY_SANITY_2.
                                        let htlc_outbound = $local_tx == htlc.offered;
                                        if ( htlc_outbound && htlc.cltv_expiry + HTLC_FAIL_TIMEOUT_BLOCKS <= height) ||
                                           (!htlc_outbound && htlc.cltv_expiry <= height + CLTV_CLAIM_BUFFER && self.payment_preimages.contains_key(&htlc.payment_hash)) {
                                                log_info!(self, "Force-closing channel due to {} HTLC timeout, HTLC expiry is {}", if htlc_outbound { "outbound" } else { "inbound "}, htlc.cltv_expiry);
                                                return true;
                                        }
                                }
                        }
                }

                if let Some(ref cur_local_tx) = self.current_local_signed_commitment_tx {
                        scan_commitment!(cur_local_tx.htlc_outputs.iter().map(|&(ref a, _, _)| a), true);
                }

                if let Storage::Local { ref current_remote_commitment_txid, ref prev_remote_commitment_txid, .. } = self.key_storage {
                        if let &Some(ref txid) = current_remote_commitment_txid {
                                if let Some(ref htlc_outputs) = self.remote_claimable_outpoints.get(txid) {
                                        scan_commitment!(htlc_outputs.iter().map(|&(ref a, _)| a), false);
                                }
                        }
                        if let &Some(ref txid) = prev_remote_commitment_txid {
                                if let Some(ref htlc_outputs) = self.remote_claimable_outpoints.get(txid) {
                                        scan_commitment!(htlc_outputs.iter().map(|&(ref a, _)| a), false);
                                }
                        }
                }

                false
        }

        /// Check if any transaction broadcasted is resolving HTLC output by a success or timeout on a local
        /// or remote commitment tx, if so send back the source, preimage if found and payment_hash of resolved HTLC
        fn is_resolving_htlc_output(&mut self, tx: &Transaction) -> Vec<(HTLCSource, Option<PaymentPreimage>, PaymentHash)> {
                let mut htlc_updated = Vec::new();

                'outer_loop: for input in &tx.input {
                        let mut payment_data = None;
                        let revocation_sig_claim = (input.witness.len() == 3 && input.witness[2].len() == OFFERED_HTLC_SCRIPT_WEIGHT && input.witness[1].len() == 33)
                                || (input.witness.len() == 3 && input.witness[2].len() == ACCEPTED_HTLC_SCRIPT_WEIGHT && input.witness[1].len() == 33);
                        let accepted_preimage_claim = input.witness.len() == 5 && input.witness[4].len() == ACCEPTED_HTLC_SCRIPT_WEIGHT;
                        let offered_preimage_claim = input.witness.len() == 3 && input.witness[2].len() == OFFERED_HTLC_SCRIPT_WEIGHT;

                        macro_rules! log_claim {
                                ($tx_info: expr, $local_tx: expr, $htlc: expr, $source_avail: expr) => {
                                        // We found the output in question, but aren't failing it backwards
                                        // as we have no corresponding source. This implies either it is an
                                        // inbound HTLC or an outbound HTLC on a revoked transaction.
                                        let outbound_htlc = $local_tx == $htlc.offered;
                                        if ($local_tx && revocation_sig_claim) ||
                                                        (outbound_htlc && !$source_avail && (accepted_preimage_claim || offered_preimage_claim)) {
                                                log_error!(self, "Input spending {} ({}:{}) in {} resolves {} HTLC with payment hash {} with {}!",
                                                        $tx_info, input.previous_output.txid, input.previous_output.vout, tx.txid(),
                                                        if outbound_htlc { "outbound" } else { "inbound" }, log_bytes!($htlc.payment_hash.0),
                                                        if revocation_sig_claim { "revocation sig" } else { "preimage claim after we'd passed the HTLC resolution back" });
                                        } else {
                                                log_info!(self, "Input spending {} ({}:{}) in {} resolves {} HTLC with payment hash {} with {}",
                                                        $tx_info, input.previous_output.txid, input.previous_output.vout, tx.txid(),
                                                        if outbound_htlc { "outbound" } else { "inbound" }, log_bytes!($htlc.payment_hash.0),
                                                        if revocation_sig_claim { "revocation sig" } else if accepted_preimage_claim || offered_preimage_claim { "preimage" } else { "timeout" });
                                        }
                                }
                        }

                        macro_rules! scan_commitment {
                                ($htlcs: expr, $tx_info: expr, $local_tx: expr) => {
                                        for (ref htlc_output, source_option) in $htlcs {
                                                if Some(input.previous_output.vout) == htlc_output.transaction_output_index {
                                                        if let Some(ref source) = source_option {
                                                                log_claim!($tx_info, $local_tx, htlc_output, true);
                                                                // We have a resolution of an HTLC either from one of our latest
                                                                // local commitment transactions or an unrevoked remote commitment
                                                                // transaction. This implies we either learned a preimage, the HTLC
                                                                // has timed out, or we screwed up. In any case, we should now
                                                                // resolve the source HTLC with the original sender.
                                                                payment_data = Some(((*source).clone(), htlc_output.payment_hash));
                                                        } else {
                                                                log_claim!($tx_info, $local_tx, htlc_output, false);
                                                                continue 'outer_loop;
                                                        }
                                                }
                                        }
                                }
                        }

                        if let Some(ref current_local_signed_commitment_tx) = self.current_local_signed_commitment_tx {
                                if input.previous_output.txid == current_local_signed_commitment_tx.txid {
                                        scan_commitment!(current_local_signed_commitment_tx.htlc_outputs.iter().map(|&(ref a, _, ref b)| (a, b.as_ref())),
                                                "our latest local commitment tx", true);
                                }
                        }
                        if let Some(ref prev_local_signed_commitment_tx) = self.prev_local_signed_commitment_tx {
                                if input.previous_output.txid == prev_local_signed_commitment_tx.txid {
                                        scan_commitment!(prev_local_signed_commitment_tx.htlc_outputs.iter().map(|&(ref a, _, ref b)| (a, b.as_ref())),
                                                "our previous local commitment tx", true);
                                }
                        }
                        if let Some(ref htlc_outputs) = self.remote_claimable_outpoints.get(&input.previous_output.txid) {
                                scan_commitment!(htlc_outputs.iter().map(|&(ref a, ref b)| (a, (b.as_ref().clone()).map(|boxed| &**boxed))),
                                        "remote commitment tx", false);
                        }

                        // Check that scan_commitment, above, decided there is some source worth relaying an
                        // HTLC resolution backwards to and figure out whether we learned a preimage from it.
                        if let Some((source, payment_hash)) = payment_data {
                                let mut payment_preimage = PaymentPreimage([0; 32]);
                                if accepted_preimage_claim {
                                        payment_preimage.0.copy_from_slice(&input.witness[3]);
                                        htlc_updated.push((source, Some(payment_preimage), payment_hash));
                                } else if offered_preimage_claim {
                                        payment_preimage.0.copy_from_slice(&input.witness[1]);
                                        htlc_updated.push((source, Some(payment_preimage), payment_hash));
                                } else {
                                        htlc_updated.push((source, None, payment_hash));
                                }
                        }
                }
                htlc_updated
        }
}

const MAX_ALLOC_SIZE: usize = 64*1024;

impl<R: ::std::io::Read> ReadableArgs<R, Arc<Logger>> for (Sha256dHash, ChannelMonitor) {
        fn read(reader: &mut R, logger: Arc<Logger>) -> Result<Self, DecodeError> {
                let secp_ctx = Secp256k1::new();
                macro_rules! unwrap_obj {
                        ($key: expr) => {
                                match $key {
                                        Ok(res) => res,
                                        Err(_) => return Err(DecodeError::InvalidValue),
                                }
                        }
                }

                let _ver: u8 = Readable::read(reader)?;
                let min_ver: u8 = Readable::read(reader)?;
                if min_ver > SERIALIZATION_VERSION {
                        return Err(DecodeError::UnknownVersion);
                }

                let commitment_transaction_number_obscure_factor = <U48 as Readable<R>>::read(reader)?.0;

                let key_storage = match <u8 as Readable<R>>::read(reader)? {
                        0 => {
                                let revocation_base_key = Readable::read(reader)?;
                                let htlc_base_key = Readable::read(reader)?;
                                let delayed_payment_base_key = Readable::read(reader)?;
                                let payment_base_key = Readable::read(reader)?;
                                let shutdown_pubkey = Readable::read(reader)?;
                                let prev_latest_per_commitment_point = Readable::read(reader)?;
                                let latest_per_commitment_point = Readable::read(reader)?;
                                // Technically this can fail and serialize fail a round-trip, but only for serialization of
                                // barely-init'd ChannelMonitors that we can't do anything with.
                                let outpoint = OutPoint {
                                        txid: Readable::read(reader)?,
                                        index: Readable::read(reader)?,
                                };
                                let funding_info = Some((outpoint, Readable::read(reader)?));
                                let current_remote_commitment_txid = Readable::read(reader)?;
                                let prev_remote_commitment_txid = Readable::read(reader)?;
                                Storage::Local {
                                        revocation_base_key,
                                        htlc_base_key,
                                        delayed_payment_base_key,
                                        payment_base_key,
                                        shutdown_pubkey,
                                        prev_latest_per_commitment_point,
                                        latest_per_commitment_point,
                                        funding_info,
                                        current_remote_commitment_txid,
                                        prev_remote_commitment_txid,
                                }
                        },
                        _ => return Err(DecodeError::InvalidValue),
                };

                let their_htlc_base_key = Some(Readable::read(reader)?);
                let their_delayed_payment_base_key = Some(Readable::read(reader)?);

                let their_cur_revocation_points = {
                        let first_idx = <U48 as Readable<R>>::read(reader)?.0;
                        if first_idx == 0 {
                                None
                        } else {
                                let first_point = Readable::read(reader)?;
                                let second_point_slice: [u8; 33] = Readable::read(reader)?;
                                if second_point_slice[0..32] == [0; 32] && second_point_slice[32] == 0 {
                                        Some((first_idx, first_point, None))
                                } else {
                                        Some((first_idx, first_point, Some(unwrap_obj!(PublicKey::from_slice(&second_point_slice)))))
                                }
                        }
                };

                let our_to_self_delay: u16 = Readable::read(reader)?;
                let their_to_self_delay: Option<u16> = Some(Readable::read(reader)?);

                let mut old_secrets = [([0; 32], 1 << 48); 49];
                for &mut (ref mut secret, ref mut idx) in old_secrets.iter_mut() {
                        *secret = Readable::read(reader)?;
                        *idx = Readable::read(reader)?;
                }

                macro_rules! read_htlc_in_commitment {
                        () => {
                                {
                                        let offered: bool = Readable::read(reader)?;
                                        let amount_msat: u64 = Readable::read(reader)?;
                                        let cltv_expiry: u32 = Readable::read(reader)?;
                                        let payment_hash: PaymentHash = Readable::read(reader)?;
                                        let transaction_output_index: Option<u32> = Readable::read(reader)?;

                                        HTLCOutputInCommitment {
                                                offered, amount_msat, cltv_expiry, payment_hash, transaction_output_index
                                        }
                                }
                        }
                }

                let remote_claimable_outpoints_len: u64 = Readable::read(reader)?;
                let mut remote_claimable_outpoints = HashMap::with_capacity(cmp::min(remote_claimable_outpoints_len as usize, MAX_ALLOC_SIZE / 64));
                for _ in 0..remote_claimable_outpoints_len {
                        let txid: Sha256dHash = Readable::read(reader)?;
                        let htlcs_count: u64 = Readable::read(reader)?;
                        let mut htlcs = Vec::with_capacity(cmp::min(htlcs_count as usize, MAX_ALLOC_SIZE / 32));
                        for _ in 0..htlcs_count {
                                htlcs.push((read_htlc_in_commitment!(), <Option<HTLCSource> as Readable<R>>::read(reader)?.map(|o: HTLCSource| Box::new(o))));
                        }
                        if let Some(_) = remote_claimable_outpoints.insert(txid, htlcs) {
                                return Err(DecodeError::InvalidValue);
                        }
                }

                let remote_commitment_txn_on_chain_len: u64 = Readable::read(reader)?;
                let mut remote_commitment_txn_on_chain = HashMap::with_capacity(cmp::min(remote_commitment_txn_on_chain_len as usize, MAX_ALLOC_SIZE / 32));
                for _ in 0..remote_commitment_txn_on_chain_len {
                        let txid: Sha256dHash = Readable::read(reader)?;
                        let commitment_number = <U48 as Readable<R>>::read(reader)?.0;
                        let outputs_count = <u64 as Readable<R>>::read(reader)?;
                        let mut outputs = Vec::with_capacity(cmp::min(outputs_count as usize, MAX_ALLOC_SIZE / 8));
                        for _ in 0..outputs_count {
                                outputs.push(Readable::read(reader)?);
                        }
                        if let Some(_) = remote_commitment_txn_on_chain.insert(txid, (commitment_number, outputs)) {
                                return Err(DecodeError::InvalidValue);
                        }
                }

                let remote_hash_commitment_number_len: u64 = Readable::read(reader)?;
                let mut remote_hash_commitment_number = HashMap::with_capacity(cmp::min(remote_hash_commitment_number_len as usize, MAX_ALLOC_SIZE / 32));
                for _ in 0..remote_hash_commitment_number_len {
                        let payment_hash: PaymentHash = Readable::read(reader)?;
                        let commitment_number = <U48 as Readable<R>>::read(reader)?.0;
                        if let Some(_) = remote_hash_commitment_number.insert(payment_hash, commitment_number) {
                                return Err(DecodeError::InvalidValue);
                        }
                }

                macro_rules! read_local_tx {
                        () => {
                                {
                                        let tx = match Transaction::consensus_decode(reader.by_ref()) {
                                                Ok(tx) => tx,
                                                Err(e) => match e {
                                                        encode::Error::Io(ioe) => return Err(DecodeError::Io(ioe)),
                                                        _ => return Err(DecodeError::InvalidValue),
                                                },
                                        };

                                        if tx.input.is_empty() {
                                                // Ensure tx didn't hit the 0-input ambiguity case.
                                                return Err(DecodeError::InvalidValue);
                                        }

                                        let revocation_key = Readable::read(reader)?;
                                        let a_htlc_key = Readable::read(reader)?;
                                        let b_htlc_key = Readable::read(reader)?;
                                        let delayed_payment_key = Readable::read(reader)?;
                                        let feerate_per_kw: u64 = Readable::read(reader)?;

                                        let htlcs_len: u64 = Readable::read(reader)?;
                                        let mut htlcs = Vec::with_capacity(cmp::min(htlcs_len as usize, MAX_ALLOC_SIZE / 128));
                                        for _ in 0..htlcs_len {
                                                let htlc = read_htlc_in_commitment!();
                                                let sigs = match <u8 as Readable<R>>::read(reader)? {
                                                        0 => None,
                                                        1 => Some((Readable::read(reader)?, Readable::read(reader)?)),
                                                        _ => return Err(DecodeError::InvalidValue),
                                                };
                                                htlcs.push((htlc, sigs, Readable::read(reader)?));
                                        }

                                        LocalSignedTx {
                                                txid: tx.txid(),
                                                tx, revocation_key, a_htlc_key, b_htlc_key, delayed_payment_key, feerate_per_kw,
                                                htlc_outputs: htlcs
                                        }
                                }
                        }
                }

                let prev_local_signed_commitment_tx = match <u8 as Readable<R>>::read(reader)? {
                        0 => None,
                        1 => {
                                Some(read_local_tx!())
                        },
                        _ => return Err(DecodeError::InvalidValue),
                };

                let current_local_signed_commitment_tx = match <u8 as Readable<R>>::read(reader)? {
                        0 => None,
                        1 => {
                                Some(read_local_tx!())
                        },
                        _ => return Err(DecodeError::InvalidValue),
                };

                let current_remote_commitment_number = <U48 as Readable<R>>::read(reader)?.0;

                let payment_preimages_len: u64 = Readable::read(reader)?;
                let mut payment_preimages = HashMap::with_capacity(cmp::min(payment_preimages_len as usize, MAX_ALLOC_SIZE / 32));
                for _ in 0..payment_preimages_len {
                        let preimage: PaymentPreimage = Readable::read(reader)?;
                        let hash = PaymentHash(Sha256::hash(&preimage.0[..]).into_inner());
                        if let Some(_) = payment_preimages.insert(hash, preimage) {
                                return Err(DecodeError::InvalidValue);
                        }
                }

                let last_block_hash: Sha256dHash = Readable::read(reader)?;
                let destination_script = Readable::read(reader)?;

                Ok((last_block_hash.clone(), ChannelMonitor {
                        commitment_transaction_number_obscure_factor,

                        key_storage,
                        their_htlc_base_key,
                        their_delayed_payment_base_key,
                        their_cur_revocation_points,

                        our_to_self_delay,
                        their_to_self_delay,

                        old_secrets,
                        remote_claimable_outpoints,
                        remote_commitment_txn_on_chain,
                        remote_hash_commitment_number,

                        prev_local_signed_commitment_tx,
                        current_local_signed_commitment_tx,
                        current_remote_commitment_number,

                        payment_preimages,

                        destination_script,
                        last_block_hash,
                        secp_ctx,
                        logger,
                }))
        }

}

#[cfg(test)]
mod tests {
        use bitcoin::blockdata::script::Script;
        use bitcoin::blockdata::transaction::Transaction;
        use bitcoin_hashes::Hash;
        use bitcoin_hashes::sha256::Hash as Sha256;
        use hex;
        use ln::channelmanager::{PaymentPreimage, PaymentHash};
        use ln::channelmonitor::ChannelMonitor;
        use ln::chan_utils::{HTLCOutputInCommitment, TxCreationKeys};
        use util::test_utils::TestLogger;
        use secp256k1::key::{SecretKey,PublicKey};
        use secp256k1::Secp256k1;
        use rand::{thread_rng,Rng};
        use std::sync::Arc;

        #[test]
        fn test_per_commitment_storage() {
                // Test vectors from BOLT 3:
                let mut secrets: Vec<[u8; 32]> = Vec::new();
                let mut monitor: ChannelMonitor;
                let secp_ctx = Secp256k1::new();
                let logger = Arc::new(TestLogger::new());

                macro_rules! test_secrets {
                        () => {
                                let mut idx = 281474976710655;
                                for secret in secrets.iter() {
                                        assert_eq!(monitor.get_secret(idx).unwrap(), *secret);
                                        idx -= 1;
                                }
                                assert_eq!(monitor.get_min_seen_secret(), idx + 1);
                                assert!(monitor.get_secret(idx).is_none());
                        };
                }

                {
                        // insert_secret correct sequence
                        monitor = ChannelMonitor::new(&SecretKey::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[43; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()), 0, Script::new(), logger.clone());
                        secrets.clear();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c65716add7aa98ba7acb236352d665cab17345fe45b55fb879ff80e6bd0c41dd").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("969660042a28f32d9be17344e09374b379962d03db1574df5a8a5a47e19ce3f2").unwrap());
                        monitor.provide_secret(281474976710650, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("a5a64476122ca0925fb344bdc1854c1c0a59fc614298e50a33e331980a220f32").unwrap());
                        monitor.provide_secret(281474976710649, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("05cde6323d949933f7f7b78776bcc1ea6d9b31447732e3802e1f7ac44b650e17").unwrap());
                        monitor.provide_secret(281474976710648, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();
                }

                {
                        // insert_secret #1 incorrect
                        monitor = ChannelMonitor::new(&SecretKey::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[43; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()), 0, Script::new(), logger.clone());
                        secrets.clear();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("02a40c85b6f28da08dfdbe0926c53fab2de6d28c10301f8f7c4073d5e42e3148").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710654, secrets.last().unwrap().clone()).unwrap_err().0,
                                        "Previous secret did not match new one");
                }

                {
                        // insert_secret #2 incorrect (#1 derived from incorrect)
                        monitor = ChannelMonitor::new(&SecretKey::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[43; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()), 0, Script::new(), logger.clone());
                        secrets.clear();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("02a40c85b6f28da08dfdbe0926c53fab2de6d28c10301f8f7c4073d5e42e3148").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("dddc3a8d14fddf2b68fa8c7fbad2748274937479dd0f8930d5ebb4ab6bd866a3").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710652, secrets.last().unwrap().clone()).unwrap_err().0,
                                        "Previous secret did not match new one");
                }

                {
                        // insert_secret #3 incorrect
                        monitor = ChannelMonitor::new(&SecretKey::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[43; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()), 0, Script::new(), logger.clone());
                        secrets.clear();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c51a18b13e8527e579ec56365482c62f180b7d5760b46e9477dae59e87ed423a").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710652, secrets.last().unwrap().clone()).unwrap_err().0,
                                        "Previous secret did not match new one");
                }

                {
                        // insert_secret #4 incorrect (1,2,3 derived from incorrect)
                        monitor = ChannelMonitor::new(&SecretKey::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[43; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()), 0, Script::new(), logger.clone());
                        secrets.clear();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("02a40c85b6f28da08dfdbe0926c53fab2de6d28c10301f8f7c4073d5e42e3148").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("dddc3a8d14fddf2b68fa8c7fbad2748274937479dd0f8930d5ebb4ab6bd866a3").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c51a18b13e8527e579ec56365482c62f180b7d5760b46e9477dae59e87ed423a").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("ba65d7b0ef55a3ba300d4e87af29868f394f8f138d78a7011669c79b37b936f4").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c65716add7aa98ba7acb236352d665cab17345fe45b55fb879ff80e6bd0c41dd").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("969660042a28f32d9be17344e09374b379962d03db1574df5a8a5a47e19ce3f2").unwrap());
                        monitor.provide_secret(281474976710650, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("a5a64476122ca0925fb344bdc1854c1c0a59fc614298e50a33e331980a220f32").unwrap());
                        monitor.provide_secret(281474976710649, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("05cde6323d949933f7f7b78776bcc1ea6d9b31447732e3802e1f7ac44b650e17").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710648, secrets.last().unwrap().clone()).unwrap_err().0,
                                        "Previous secret did not match new one");
                }

                {
                        // insert_secret #5 incorrect
                        monitor = ChannelMonitor::new(&SecretKey::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[43; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()), 0, Script::new(), logger.clone());
                        secrets.clear();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("631373ad5f9ef654bb3dade742d09504c567edd24320d2fcd68e3cc47e2ff6a6").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("969660042a28f32d9be17344e09374b379962d03db1574df5a8a5a47e19ce3f2").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710650, secrets.last().unwrap().clone()).unwrap_err().0,
                                        "Previous secret did not match new one");
                }

                {
                        // insert_secret #6 incorrect (5 derived from incorrect)
                        monitor = ChannelMonitor::new(&SecretKey::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[43; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()), 0, Script::new(), logger.clone());
                        secrets.clear();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("631373ad5f9ef654bb3dade742d09504c567edd24320d2fcd68e3cc47e2ff6a6").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("b7e76a83668bde38b373970155c868a653304308f9896692f904a23731224bb1").unwrap());
                        monitor.provide_secret(281474976710650, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("a5a64476122ca0925fb344bdc1854c1c0a59fc614298e50a33e331980a220f32").unwrap());
                        monitor.provide_secret(281474976710649, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("05cde6323d949933f7f7b78776bcc1ea6d9b31447732e3802e1f7ac44b650e17").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710648, secrets.last().unwrap().clone()).unwrap_err().0,
                                        "Previous secret did not match new one");
                }

                {
                        // insert_secret #7 incorrect
                        monitor = ChannelMonitor::new(&SecretKey::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[43; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()), 0, Script::new(), logger.clone());
                        secrets.clear();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c65716add7aa98ba7acb236352d665cab17345fe45b55fb879ff80e6bd0c41dd").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("969660042a28f32d9be17344e09374b379962d03db1574df5a8a5a47e19ce3f2").unwrap());
                        monitor.provide_secret(281474976710650, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("e7971de736e01da8ed58b94c2fc216cb1dca9e326f3a96e7194fe8ea8af6c0a3").unwrap());
                        monitor.provide_secret(281474976710649, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("05cde6323d949933f7f7b78776bcc1ea6d9b31447732e3802e1f7ac44b650e17").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710648, secrets.last().unwrap().clone()).unwrap_err().0,
                                        "Previous secret did not match new one");
                }

                {
                        // insert_secret #8 incorrect
                        monitor = ChannelMonitor::new(&SecretKey::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[43; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()), 0, Script::new(), logger.clone());
                        secrets.clear();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("c65716add7aa98ba7acb236352d665cab17345fe45b55fb879ff80e6bd0c41dd").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("969660042a28f32d9be17344e09374b379962d03db1574df5a8a5a47e19ce3f2").unwrap());
                        monitor.provide_secret(281474976710650, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("a5a64476122ca0925fb344bdc1854c1c0a59fc614298e50a33e331980a220f32").unwrap());
                        monitor.provide_secret(281474976710649, secrets.last().unwrap().clone()).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex::decode("a7efbc61aac46d34f77778bac22c8a20c6a46ca460addc49009bda875ec88fa4").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710648, secrets.last().unwrap().clone()).unwrap_err().0,
                                        "Previous secret did not match new one");
                }
        }

        #[test]
        fn test_prune_preimages() {
                let secp_ctx = Secp256k1::new();
                let logger = Arc::new(TestLogger::new());

                let dummy_key = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                macro_rules! dummy_keys {
                        () => {
                                {
                                        TxCreationKeys {
                                                per_commitment_point: dummy_key.clone(),
                                                revocation_key: dummy_key.clone(),
                                                a_htlc_key: dummy_key.clone(),
                                                b_htlc_key: dummy_key.clone(),
                                                a_delayed_payment_key: dummy_key.clone(),
                                                b_payment_key: dummy_key.clone(),
                                        }
                                }
                        }
                }
                let dummy_tx = Transaction { version: 0, lock_time: 0, input: Vec::new(), output: Vec::new() };

                let mut preimages = Vec::new();
                {
                        let mut rng  = thread_rng();
                        for _ in 0..20 {
                                let mut preimage = PaymentPreimage([0; 32]);
                                rng.fill_bytes(&mut preimage.0[..]);
                                let hash = PaymentHash(Sha256::hash(&preimage.0[..]).into_inner());
                                preimages.push((preimage, hash));
                        }
                }

                macro_rules! preimages_slice_to_htlc_outputs {
                        ($preimages_slice: expr) => {
                                {
                                        let mut res = Vec::new();
                                        for (idx, preimage) in $preimages_slice.iter().enumerate() {
                                                res.push((HTLCOutputInCommitment {
                                                        offered: true,
                                                        amount_msat: 0,
                                                        cltv_expiry: 0,
                                                        payment_hash: preimage.1.clone(),
                                                        transaction_output_index: Some(idx as u32),
                                                }, None));
                                        }
                                        res
                                }
                        }
                }
                macro_rules! preimages_to_local_htlcs {
                        ($preimages_slice: expr) => {
                                {
                                        let mut inp = preimages_slice_to_htlc_outputs!($preimages_slice);
                                        let res: Vec<_> = inp.drain(..).map(|e| { (e.0, None, e.1) }).collect();
                                        res
                                }
                        }
                }

                macro_rules! test_preimages_exist {
                        ($preimages_slice: expr, $monitor: expr) => {
                                for preimage in $preimages_slice {
                                        assert!($monitor.payment_preimages.contains_key(&preimage.1));
                                }
                        }
                }

                // Prune with one old state and a local commitment tx holding a few overlaps with the
                // old state.
                let mut monitor = ChannelMonitor::new(&SecretKey::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[43; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()), 0, Script::new(), logger.clone());
                monitor.set_their_to_self_delay(10);

                monitor.provide_latest_local_commitment_tx_info(dummy_tx.clone(), dummy_keys!(), 0, preimages_to_local_htlcs!(preimages[0..10]));
                monitor.provide_latest_remote_commitment_tx_info(&dummy_tx, preimages_slice_to_htlc_outputs!(preimages[5..15]), 281474976710655, dummy_key);
                monitor.provide_latest_remote_commitment_tx_info(&dummy_tx, preimages_slice_to_htlc_outputs!(preimages[15..20]), 281474976710654, dummy_key);
                monitor.provide_latest_remote_commitment_tx_info(&dummy_tx, preimages_slice_to_htlc_outputs!(preimages[17..20]), 281474976710653, dummy_key);
                monitor.provide_latest_remote_commitment_tx_info(&dummy_tx, preimages_slice_to_htlc_outputs!(preimages[18..20]), 281474976710652, dummy_key);
                for &(ref preimage, ref hash) in preimages.iter() {
                        monitor.provide_payment_preimage(hash, preimage);
                }

                // Now provide a secret, pruning preimages 10-15
                let mut secret = [0; 32];
                secret[0..32].clone_from_slice(&hex::decode("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                monitor.provide_secret(281474976710655, secret.clone()).unwrap();
                assert_eq!(monitor.payment_preimages.len(), 15);
                test_preimages_exist!(&preimages[0..10], monitor);
                test_preimages_exist!(&preimages[15..20], monitor);

                // Now provide a further secret, pruning preimages 15-17
                secret[0..32].clone_from_slice(&hex::decode("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                monitor.provide_secret(281474976710654, secret.clone()).unwrap();
                assert_eq!(monitor.payment_preimages.len(), 13);
                test_preimages_exist!(&preimages[0..10], monitor);
                test_preimages_exist!(&preimages[17..20], monitor);

                // Now update local commitment tx info, pruning only element 18 as we still care about the
                // previous commitment tx's preimages too
                monitor.provide_latest_local_commitment_tx_info(dummy_tx.clone(), dummy_keys!(), 0, preimages_to_local_htlcs!(preimages[0..5]));
                secret[0..32].clone_from_slice(&hex::decode("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                monitor.provide_secret(281474976710653, secret.clone()).unwrap();
                assert_eq!(monitor.payment_preimages.len(), 12);
                test_preimages_exist!(&preimages[0..10], monitor);
                test_preimages_exist!(&preimages[18..20], monitor);

                // But if we do it again, we'll prune 5-10
                monitor.provide_latest_local_commitment_tx_info(dummy_tx.clone(), dummy_keys!(), 0, preimages_to_local_htlcs!(preimages[0..3]));
                secret[0..32].clone_from_slice(&hex::decode("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                monitor.provide_secret(281474976710652, secret.clone()).unwrap();
                assert_eq!(monitor.payment_preimages.len(), 5);
                test_preimages_exist!(&preimages[0..5], monitor);
        }

        // Further testing is done in the ChannelManager integration tests.
}