Implement channelmonitor (de)serialization (fixes #45)

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

use bitcoin::blockdata::block::BlockHeader;
use bitcoin::blockdata::transaction::{TxIn,TxOut,SigHashType,Transaction};
use bitcoin::blockdata::script::Script;
use bitcoin::network::serialize;
use bitcoin::util::hash::Sha256dHash;
use bitcoin::util::bip143;

use crypto::digest::Digest;

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

use ln::msgs::HandleError;
use ln::chan_utils;
use ln::chan_utils::HTLCOutputInCommitment;
use chain::chaininterface::{ChainListener, ChainWatchInterface, BroadcasterInterface};
use chain::transaction::OutPoint;
use util::sha2::Sha256;
use util::byte_utils;

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

pub enum ChannelMonitorUpdateErr {
        /// Used to indicate a temporary failure (eg connection to a watchtower 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.
        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.
        PermanentFailure,
}

/// 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`.
        fn add_update_monitor(&self, funding_txo: OutPoint, monitor: ChannelMonitor) -> Result<(), ChannelMonitorUpdateErr>;
}

/// 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> {
        monitors: Mutex<HashMap<Key, ChannelMonitor>>,
        chain_monitor: Arc<ChainWatchInterface>,
        broadcaster: Arc<BroadcasterInterface>
}

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 monitors = self.monitors.lock().unwrap();
                for monitor in monitors.values() {
                        monitor.block_connected(txn_matched, height, &*self.broadcaster);
                }
        }

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

impl<Key : Send + cmp::Eq + hash::Hash + 'static> SimpleManyChannelMonitor<Key> {
        pub fn new(chain_monitor: Arc<ChainWatchInterface>, broadcaster: Arc<BroadcasterInterface>) -> Arc<SimpleManyChannelMonitor<Key>> {
                let res = Arc::new(SimpleManyChannelMonitor {
                        monitors: Mutex::new(HashMap::new()),
                        chain_monitor,
                        broadcaster
                });
                let weak_res = Arc::downgrade(&res);
                res.chain_monitor.register_listener(weak_res);
                res
        }

        pub fn add_update_monitor_by_key(&self, key: Key, monitor: ChannelMonitor) -> Result<(), HandleError> {
                let mut monitors = self.monitors.lock().unwrap();
                match monitors.get_mut(&key) {
                        Some(orig_monitor) => return orig_monitor.insert_combine(monitor),
                        None => {}
                };
                match monitor.funding_txo {
                        None => self.chain_monitor.watch_all_txn(),
                        Some(outpoint) => self.chain_monitor.install_watch_outpoint((outpoint.txid, outpoint.index as u32)),
                }
                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),
                }
        }
}

/// 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.
const CLTV_CLAIM_BUFFER: u32 = 6;

#[derive(Clone)]
enum KeyStorage {
        PrivMode {
                revocation_base_key: SecretKey,
                htlc_base_key: SecretKey,
        },
        SigsMode {
                revocation_base_key: PublicKey,
                htlc_base_key: PublicKey,
                sigs: HashMap<Sha256dHash, Signature>,
        }
}

#[derive(Clone)]
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, Signature, Signature)>,
}

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

pub struct ChannelMonitor {
        funding_txo: Option<OutPoint>,
        commitment_transaction_number_obscure_factor: u64,

        key_storage: KeyStorage,
        delayed_payment_base_key: PublicKey,
        their_htlc_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>>,
        /// 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: Mutex<HashMap<Sha256dHash, u64>>,
        /// 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<[u8; 32], 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>,

        payment_preimages: HashMap<[u8; 32], [u8; 32]>,

        destination_script: Script,
        secp_ctx: Secp256k1, //TODO: dedup this a bit...
}
impl Clone for ChannelMonitor {
        fn clone(&self) -> Self {
                ChannelMonitor {
                        funding_txo: self.funding_txo.clone(),
                        commitment_transaction_number_obscure_factor: self.commitment_transaction_number_obscure_factor.clone(),

                        key_storage: self.key_storage.clone(),
                        delayed_payment_base_key: self.delayed_payment_base_key.clone(),
                        their_htlc_base_key: self.their_htlc_base_key.clone(),
                        their_cur_revocation_points: self.their_cur_revocation_points.clone(),

                        our_to_self_delay: self.our_to_self_delay,
                        their_to_self_delay: self.their_to_self_delay,

                        old_secrets: self.old_secrets.clone(),
                        remote_claimable_outpoints: self.remote_claimable_outpoints.clone(),
                        remote_commitment_txn_on_chain: Mutex::new((*self.remote_commitment_txn_on_chain.lock().unwrap()).clone()),
                        remote_hash_commitment_number: self.remote_hash_commitment_number.clone(),

                        prev_local_signed_commitment_tx: self.prev_local_signed_commitment_tx.clone(),
                        current_local_signed_commitment_tx: self.current_local_signed_commitment_tx.clone(),

                        payment_preimages: self.payment_preimages.clone(),

                        destination_script: self.destination_script.clone(),
                        secp_ctx: self.secp_ctx.clone(),
                }
        }
}

impl ChannelMonitor {
        pub fn new(revocation_base_key: &SecretKey, delayed_payment_base_key: &PublicKey, htlc_base_key: &SecretKey, our_to_self_delay: u16, destination_script: Script) -> ChannelMonitor {
                ChannelMonitor {
                        funding_txo: None,
                        commitment_transaction_number_obscure_factor: 0,

                        key_storage: KeyStorage::PrivMode {
                                revocation_base_key: revocation_base_key.clone(),
                                htlc_base_key: htlc_base_key.clone(),
                        },
                        delayed_payment_base_key: delayed_payment_base_key.clone(),
                        their_htlc_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: Mutex::new(HashMap::new()),
                        remote_hash_commitment_number: HashMap::new(),

                        prev_local_signed_commitment_tx: None,
                        current_local_signed_commitment_tx: None,

                        payment_preimages: HashMap::new(),

                        destination_script: destination_script,
                        secp_ctx: Secp256k1::new(),
                }
        }

        #[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);
                                let mut sha = Sha256::new();
                                sha.input(&res);
                                sha.result(&mut res);
                        }
                }
                res
        }

        /// Inserts a revocation secret into this channel monitor. Also optionally tracks the next
        /// revocation point which may be required to claim HTLC outputs which we know the preimage of
        /// in case the remote end force-closes using their latest state. 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], their_next_revocation_point: Option<(u64, PublicKey)>) -> Result<(), HandleError> {
                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(HandleError{err: "Previous secret did not match new one", msg: None})
                        }
                }
                self.old_secrets[pos as usize] = (secret, idx);

                if let Some(new_revocation_point) = their_next_revocation_point {
                        match self.their_cur_revocation_points {
                                Some(old_points) => {
                                        if old_points.0 == new_revocation_point.0 + 1 {
                                                self.their_cur_revocation_points = Some((old_points.0, old_points.1, Some(new_revocation_point.1)));
                                        } else if old_points.0 == new_revocation_point.0 + 2 {
                                                if let Some(old_second_point) = old_points.2 {
                                                        self.their_cur_revocation_points = Some((old_points.0 - 1, old_second_point, Some(new_revocation_point.1)));
                                                } else {
                                                        self.their_cur_revocation_points = Some((new_revocation_point.0, new_revocation_point.1, None));
                                                }
                                        } else {
                                                self.their_cur_revocation_points = Some((new_revocation_point.0, new_revocation_point.1, None));
                                        }
                                },
                                None => {
                                        self.their_cur_revocation_points = Some((new_revocation_point.0, new_revocation_point.1, 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>, commitment_number: u64) {
                // 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 htlc in &htlc_outputs {
                        self.remote_hash_commitment_number.insert(htlc.payment_hash, commitment_number);
                }
                self.remote_claimable_outpoints.insert(unsigned_commitment_tx.txid(), htlc_outputs);
        }

        /// 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.
        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, Signature, Signature)>) {
                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,
                });
        }

        /// 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: &[u8; 32], payment_preimage: &[u8; 32]) {
                self.payment_preimages.insert(payment_hash.clone(), payment_preimage.clone());
        }

        pub fn insert_combine(&mut self, mut other: ChannelMonitor) -> Result<(), HandleError> {
                match self.funding_txo {
                        Some(txo) => if other.funding_txo.is_some() && other.funding_txo.unwrap() != txo {
                                return Err(HandleError{err: "Funding transaction outputs are not identical!", msg: None});
                        },
                        None => if other.funding_txo.is_some() {
                                self.funding_txo = other.funding_txo;
                        }
                }
                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(), None)?;
                }
                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;
                }
                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.
        pub(super) fn set_funding_info(&mut self, funding_info: OutPoint) {
                self.funding_txo = Some(funding_info);
        }

        pub(super) fn set_their_htlc_base_key(&mut self, their_htlc_base_key: &PublicKey) {
                self.their_htlc_base_key = Some(their_htlc_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) {
                self.funding_txo = None;
        }

        pub fn get_funding_txo(&self) -> Option<OutPoint> {
                self.funding_txo
        }

        /// Serializes into a vec, with various modes for the exposed pub fns
        fn serialize(&self, for_local_storage: bool) -> Vec<u8> {
                let mut res = Vec::new();
                res.push(SERIALIZATION_VERSION);
                res.push(MIN_SERIALIZATION_VERSION);

                match self.funding_txo {
                        Some(outpoint) => {
                                res.extend_from_slice(&outpoint.txid[..]);
                                res.extend_from_slice(&byte_utils::be16_to_array(outpoint.index));
                        },
                        None => {
                                // We haven't even been initialized...not sure why anyone is serializing us, but
                                // not much to give them.
                                return res;
                        },
                }

                // Set in initial Channel-object creation, so should always be set by now:
                res.extend_from_slice(&byte_utils::be48_to_array(self.commitment_transaction_number_obscure_factor));

                match self.key_storage {
                        KeyStorage::PrivMode { ref revocation_base_key, ref htlc_base_key } => {
                                res.push(0);
                                res.extend_from_slice(&revocation_base_key[..]);
                                res.extend_from_slice(&htlc_base_key[..]);
                        },
                        KeyStorage::SigsMode { .. } => unimplemented!(),
                }

                res.extend_from_slice(&self.delayed_payment_base_key.serialize());
                res.extend_from_slice(&self.their_htlc_base_key.as_ref().unwrap().serialize());

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

                res.extend_from_slice(&byte_utils::be16_to_array(self.our_to_self_delay));
                res.extend_from_slice(&byte_utils::be16_to_array(self.their_to_self_delay.unwrap()));

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

                macro_rules! serialize_htlc_in_commitment {
                        ($htlc_output: expr) => {
                                res.push($htlc_output.offered as u8);
                                res.extend_from_slice(&byte_utils::be64_to_array($htlc_output.amount_msat));
                                res.extend_from_slice(&byte_utils::be32_to_array($htlc_output.cltv_expiry));
                                res.extend_from_slice(&$htlc_output.payment_hash);
                                res.extend_from_slice(&byte_utils::be32_to_array($htlc_output.transaction_output_index));
                        }
                }

                res.extend_from_slice(&byte_utils::be64_to_array(self.remote_claimable_outpoints.len() as u64));
                for (txid, htlc_outputs) in self.remote_claimable_outpoints.iter() {
                        res.extend_from_slice(&txid[..]);
                        res.extend_from_slice(&byte_utils::be64_to_array(htlc_outputs.len() as u64));
                        for htlc_output in htlc_outputs.iter() {
                                serialize_htlc_in_commitment!(htlc_output);
                        }
                }

                {
                        let remote_commitment_txn_on_chain = self.remote_commitment_txn_on_chain.lock().unwrap();
                        res.extend_from_slice(&byte_utils::be64_to_array(remote_commitment_txn_on_chain.len() as u64));
                        for (txid, commitment_number) in remote_commitment_txn_on_chain.iter() {
                                res.extend_from_slice(&txid[..]);
                                res.extend_from_slice(&byte_utils::be48_to_array(*commitment_number));
                        }
                }

                if for_local_storage {
                        res.extend_from_slice(&byte_utils::be64_to_array(self.remote_hash_commitment_number.len() as u64));
                        for (payment_hash, commitment_number) in self.remote_hash_commitment_number.iter() {
                                res.extend_from_slice(payment_hash);
                                res.extend_from_slice(&byte_utils::be48_to_array(*commitment_number));
                        }
                } else {
                        res.extend_from_slice(&byte_utils::be64_to_array(0));
                }

                macro_rules! serialize_local_tx {
                        ($local_tx: expr) => {
                                let tx_ser = serialize::serialize(&$local_tx.tx).unwrap();
                                res.extend_from_slice(&byte_utils::be64_to_array(tx_ser.len() as u64));
                                res.extend_from_slice(&tx_ser);

                                res.extend_from_slice(&$local_tx.revocation_key.serialize());
                                res.extend_from_slice(&$local_tx.a_htlc_key.serialize());
                                res.extend_from_slice(&$local_tx.b_htlc_key.serialize());
                                res.extend_from_slice(&$local_tx.delayed_payment_key.serialize());

                                res.extend_from_slice(&byte_utils::be64_to_array($local_tx.feerate_per_kw));
                                res.extend_from_slice(&byte_utils::be64_to_array($local_tx.htlc_outputs.len() as u64));
                                for &(ref htlc_output, ref their_sig, ref our_sig) in $local_tx.htlc_outputs.iter() {
                                        serialize_htlc_in_commitment!(htlc_output);
                                        res.extend_from_slice(&their_sig.serialize_compact(&self.secp_ctx));
                                        res.extend_from_slice(&our_sig.serialize_compact(&self.secp_ctx));
                                }
                        }
                }

                if let Some(ref prev_local_tx) = self.prev_local_signed_commitment_tx {
                        res.push(1);
                        serialize_local_tx!(prev_local_tx);
                } else {
                        res.push(0);
                }

                if let Some(ref cur_local_tx) = self.current_local_signed_commitment_tx {
                        res.push(1);
                        serialize_local_tx!(cur_local_tx);
                } else {
                        res.push(0);
                }

                res.extend_from_slice(&byte_utils::be64_to_array(self.payment_preimages.len() as u64));
                for payment_preimage in self.payment_preimages.values() {
                        res.extend_from_slice(payment_preimage);
                }

                res.extend_from_slice(&byte_utils::be64_to_array(self.destination_script.len() as u64));
                res.extend_from_slice(&self.destination_script[..]);

                res
        }

        /// Encodes this monitor into a byte array, suitable for writing to disk.
        pub fn serialize_for_disk(&self) -> Vec<u8> {
                self.serialize(true)
        }

        /// Encodes this monitor into a byte array, suitable for sending to a remote watchtower
        pub fn serialize_for_watchtower(&self) -> Vec<u8> {
                self.serialize(false)
        }

        /// Attempts to decode a serialized monitor
        pub fn deserialize(data: &[u8]) -> Option<Self> {
                let mut read_pos = 0;
                macro_rules! read_bytes {
                        ($byte_count: expr) => {
                                {
                                        if ($byte_count as usize) + read_pos > data.len() {
                                                return None;
                                        }
                                        read_pos += $byte_count as usize;
                                        &data[read_pos - $byte_count as usize..read_pos]
                                }
                        }
                }

                let secp_ctx = Secp256k1::new();
                macro_rules! unwrap_obj {
                        ($key: expr) => {
                                match $key {
                                        Ok(res) => res,
                                        Err(_) => return None,
                                }
                        }
                }

                let _ver = read_bytes!(1)[0];
                let min_ver = read_bytes!(1)[0];
                if min_ver > SERIALIZATION_VERSION {
                        return None;
                }

                // 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 funding_txo = Some(OutPoint {
                        txid: Sha256dHash::from(read_bytes!(32)),
                        index: byte_utils::slice_to_be16(read_bytes!(2)),
                });
                let commitment_transaction_number_obscure_factor = byte_utils::slice_to_be48(read_bytes!(6));

                let key_storage = match read_bytes!(1)[0] {
                        0 => {
                                KeyStorage::PrivMode {
                                        revocation_base_key: unwrap_obj!(SecretKey::from_slice(&secp_ctx, read_bytes!(32))),
                                        htlc_base_key: unwrap_obj!(SecretKey::from_slice(&secp_ctx, read_bytes!(32))),
                                }
                        },
                        _ => return None,
                };

                let delayed_payment_base_key = unwrap_obj!(PublicKey::from_slice(&secp_ctx, read_bytes!(33)));
                let their_htlc_base_key = Some(unwrap_obj!(PublicKey::from_slice(&secp_ctx, read_bytes!(33))));

                let their_cur_revocation_points = {
                        let first_idx = byte_utils::slice_to_be48(read_bytes!(6));
                        if first_idx == 0 {
                                None
                        } else {
                                let first_point = unwrap_obj!(PublicKey::from_slice(&secp_ctx, read_bytes!(33)));
                                let second_point_slice = read_bytes!(33);
                                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(&secp_ctx, second_point_slice)))))
                                }
                        }
                };

                let our_to_self_delay = byte_utils::slice_to_be16(read_bytes!(2));
                let their_to_self_delay = Some(byte_utils::slice_to_be16(read_bytes!(2)));

                let mut old_secrets = [([0; 32], 1 << 48); 49];
                for &mut (ref mut secret, ref mut idx) in old_secrets.iter_mut() {
                        secret.copy_from_slice(read_bytes!(32));
                        *idx = byte_utils::slice_to_be64(read_bytes!(8));
                }

                macro_rules! read_htlc_in_commitment {
                        () => {
                                {
                                        let offered = match read_bytes!(1)[0] {
                                                0 => false, 1 => true,
                                                _ => return None,
                                        };
                                        let amount_msat = byte_utils::slice_to_be64(read_bytes!(8));
                                        let cltv_expiry = byte_utils::slice_to_be32(read_bytes!(4));
                                        let mut payment_hash = [0; 32];
                                        payment_hash[..].copy_from_slice(read_bytes!(32));
                                        let transaction_output_index = byte_utils::slice_to_be32(read_bytes!(4));

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

                let remote_claimable_outpoints_len = byte_utils::slice_to_be64(read_bytes!(8));
                if remote_claimable_outpoints_len > data.len() as u64 / 64 { return None; }
                let mut remote_claimable_outpoints = HashMap::with_capacity(remote_claimable_outpoints_len as usize);
                for _ in 0..remote_claimable_outpoints_len {
                        let txid = Sha256dHash::from(read_bytes!(32));
                        let outputs_count = byte_utils::slice_to_be64(read_bytes!(8));
                        if outputs_count > data.len() as u64 * 32 { return None; }
                        let mut outputs = Vec::with_capacity(outputs_count as usize);
                        for _ in 0..outputs_count {
                                outputs.push(read_htlc_in_commitment!());
                        }
                        if let Some(_) = remote_claimable_outpoints.insert(txid, outputs) {
                                return None;
                        }
                }

                let remote_commitment_txn_on_chain_len = byte_utils::slice_to_be64(read_bytes!(8));
                if remote_commitment_txn_on_chain_len > data.len() as u64 / 32 { return None; }
                let mut remote_commitment_txn_on_chain = HashMap::with_capacity(remote_commitment_txn_on_chain_len as usize);
                for _ in 0..remote_commitment_txn_on_chain_len {
                        let txid = Sha256dHash::from(read_bytes!(32));
                        let commitment_number = byte_utils::slice_to_be48(read_bytes!(6));
                        if let Some(_) = remote_commitment_txn_on_chain.insert(txid, commitment_number) {
                                return None;
                        }
                }

                let remote_hash_commitment_number_len = byte_utils::slice_to_be64(read_bytes!(8));
                if remote_hash_commitment_number_len > data.len() as u64 / 32 { return None; }
                let mut remote_hash_commitment_number = HashMap::with_capacity(remote_hash_commitment_number_len as usize);
                for _ in 0..remote_hash_commitment_number_len {
                        let mut txid = [0; 32];
                        txid[..].copy_from_slice(read_bytes!(32));
                        let commitment_number = byte_utils::slice_to_be48(read_bytes!(6));
                        if let Some(_) = remote_hash_commitment_number.insert(txid, commitment_number) {
                                return None;
                        }
                }

                macro_rules! read_local_tx {
                        () => {
                                {
                                        let tx_len = byte_utils::slice_to_be64(read_bytes!(8));
                                        let tx: Transaction = unwrap_obj!(serialize::deserialize(read_bytes!(tx_len)));

                                        let revocation_key = unwrap_obj!(PublicKey::from_slice(&secp_ctx, read_bytes!(33)));
                                        let a_htlc_key = unwrap_obj!(PublicKey::from_slice(&secp_ctx, read_bytes!(33)));
                                        let b_htlc_key = unwrap_obj!(PublicKey::from_slice(&secp_ctx, read_bytes!(33)));
                                        let delayed_payment_key = unwrap_obj!(PublicKey::from_slice(&secp_ctx, read_bytes!(33)));
                                        let feerate_per_kw = byte_utils::slice_to_be64(read_bytes!(8));

                                        let htlc_outputs_len = byte_utils::slice_to_be64(read_bytes!(8));
                                        if htlc_outputs_len > data.len() as u64 / 128 { return None; }
                                        let mut htlc_outputs = Vec::with_capacity(htlc_outputs_len as usize);
                                        for _ in 0..htlc_outputs_len {
                                                htlc_outputs.push((read_htlc_in_commitment!(),
                                                                unwrap_obj!(Signature::from_compact(&secp_ctx, read_bytes!(64))),
                                                                unwrap_obj!(Signature::from_compact(&secp_ctx, read_bytes!(64)))));
                                        }

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

                let prev_local_signed_commitment_tx = match read_bytes!(1)[0] {
                        0 => None,
                        1 => {
                                Some(read_local_tx!())
                        },
                        _ => return None,
                };

                let current_local_signed_commitment_tx = match read_bytes!(1)[0] {
                        0 => None,
                        1 => {
                                Some(read_local_tx!())
                        },
                        _ => return None,
                };

                let payment_preimages_len = byte_utils::slice_to_be64(read_bytes!(8));
                if payment_preimages_len > data.len() as u64 / 32 { return None; }
                let mut payment_preimages = HashMap::with_capacity(payment_preimages_len as usize);
                let mut sha = Sha256::new();
                for _ in 0..payment_preimages_len {
                        let mut preimage = [0; 32];
                        preimage[..].copy_from_slice(read_bytes!(32));
                        sha.reset();
                        sha.input(&preimage);
                        let mut hash = [0; 32];
                        sha.result(&mut hash);
                        if let Some(_) = payment_preimages.insert(hash, preimage) {
                                return None;
                        }
                }

                let destination_script_len = byte_utils::slice_to_be64(read_bytes!(8));
                let destination_script = Script::from(read_bytes!(destination_script_len).to_vec());

                Some(ChannelMonitor {
                        funding_txo,
                        commitment_transaction_number_obscure_factor,

                        key_storage,
                        delayed_payment_base_key,
                        their_htlc_base_key,
                        their_cur_revocation_points,

                        our_to_self_delay,
                        their_to_self_delay,

                        old_secrets,
                        remote_claimable_outpoints,
                        remote_commitment_txn_on_chain: Mutex::new(remote_commitment_txn_on_chain),
                        remote_hash_commitment_number,

                        prev_local_signed_commitment_tx,
                        current_local_signed_commitment_tx,

                        payment_preimages,

                        destination_script,
                        secp_ctx,
                })
        }

        //TODO: Functions to serialize/deserialize (with different forms depending on which information
        //we want to leave out (eg funding_txo, etc).

        /// Can only fail if idx is < get_min_seen_secret
        pub fn get_secret(&self, idx: u64) -> Result<[u8; 32], HandleError> {
                for i in 0..self.old_secrets.len() {
                        if (idx & (!((1 << i) - 1))) == self.old_secrets[i].1 {
                                return Ok(ChannelMonitor::derive_secret(self.old_secrets[i].0, i as u8, idx))
                        }
                }
                assert!(idx < self.get_min_seen_secret());
                Err(HandleError{err: "idx too low", msg: None})
        }

        pub 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
        }

        /// 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, and claim them using the revocation key (if
        /// applicable) as well.
        fn check_spend_remote_transaction(&self, tx: &Transaction, height: u32) -> Vec<Transaction> {
                // 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();
                macro_rules! ignore_error {
                        ( $thing : expr ) => {
                                match $thing {
                                        Ok(a) => a,
                                        Err(_) => return txn_to_broadcast
                                }
                        };
                }

                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);

                let commitment_number = (((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(&self.secp_ctx, &secret));
                        let (revocation_pubkey, b_htlc_key) = match self.key_storage {
                                KeyStorage::PrivMode { ref revocation_base_key, ref htlc_base_key } => {
                                        let per_commitment_point = ignore_error!(PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key));
                                        (ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, &per_commitment_point, &ignore_error!(PublicKey::from_secret_key(&self.secp_ctx, &revocation_base_key)))),
                                        ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, &per_commitment_point, &ignore_error!(PublicKey::from_secret_key(&self.secp_ctx, &htlc_base_key)))))
                                },
                                KeyStorage::SigsMode { ref revocation_base_key, ref htlc_base_key, .. } => {
                                        let per_commitment_point = ignore_error!(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)))
                                },
                        };
                        let delayed_key = ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, &ignore_error!(PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key)), &self.delayed_payment_base_key));
                        let a_htlc_key = match self.their_htlc_base_key {
                                None => return txn_to_broadcast,
                                Some(their_htlc_base_key) => ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, &ignore_error!(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 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 {
                                                prev_hash: commitment_txid,
                                                prev_index: idx as u32,
                                                script_sig: Script::new(),
                                                sequence: 0xfffffffd,
                                                witness: Vec::new(),
                                        });
                                        htlc_idxs.push(None);
                                        values.push(outp.value);
                                        total_value += outp.value;
                                        break; // There can only be one of these
                                }
                        }

                        macro_rules! sign_input {
                                ($sighash_parts: expr, $input: expr, $htlc_idx: expr, $amount: expr) => {
                                        {
                                                let (sig, redeemscript) = match self.key_storage {
                                                        KeyStorage::PrivMode { ref revocation_base_key, .. } => {
                                                                let redeemscript = if $htlc_idx.is_none() { revokeable_redeemscript.clone() } else {
                                                                        let htlc = &per_commitment_option.unwrap()[$htlc_idx.unwrap()];
                                                                        chan_utils::get_htlc_redeemscript_with_explicit_keys(htlc, &a_htlc_key, &b_htlc_key, &revocation_pubkey)
                                                                };
                                                                let sighash = ignore_error!(Message::from_slice(&$sighash_parts.sighash_all(&$input, &redeemscript, $amount)[..]));
                                                                let revocation_key = ignore_error!(chan_utils::derive_private_revocation_key(&self.secp_ctx, &per_commitment_key, &revocation_base_key));
                                                                (ignore_error!(self.secp_ctx.sign(&sighash, &revocation_key)), redeemscript)
                                                        },
                                                        KeyStorage::SigsMode { .. } => {
                                                                unimplemented!();
                                                        }
                                                };
                                                $input.witness.push(sig.serialize_der(&self.secp_ctx).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_vec());
                                        }
                                }
                        }

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

                                for (idx, htlc) in per_commitment_data.iter().enumerate() {
                                        let expected_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &a_htlc_key, &b_htlc_key, &revocation_pubkey);
                                        if htlc.transaction_output_index as usize >= tx.output.len() ||
                                                        tx.output[htlc.transaction_output_index as usize].value != htlc.amount_msat / 1000 ||
                                                        tx.output[htlc.transaction_output_index as usize].script_pubkey != expected_script.to_v0_p2wsh() {
                                                return txn_to_broadcast; // Corrupted per_commitment_data, fuck this user
                                        }
                                        let input = TxIn {
                                                prev_hash: commitment_txid,
                                                prev_index: htlc.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[htlc.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); // TODO: This is not yet tested in ChannelManager!
                                        }
                                }
                        }

                        if !inputs.is_empty() || !txn_to_broadcast.is_empty() { // ie we're confident this is actually ours
                                // We're definitely a remote commitment transaction!
                                // TODO: Register commitment_txid with the ChainWatchInterface!
                                self.remote_commitment_txn_on_chain.lock().unwrap().insert(commitment_txid, commitment_number);
                        }
                        if inputs.is_empty() { return txn_to_broadcast; } // 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);
                        }

                        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.
                        self.remote_commitment_txn_on_chain.lock().unwrap().insert(commitment_txid, commitment_number);

                        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 {
                                                KeyStorage::PrivMode { ref revocation_base_key, ref htlc_base_key } => {
                                                        (ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, revocation_point, &ignore_error!(PublicKey::from_secret_key(&self.secp_ctx, &revocation_base_key)))),
                                                        ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, revocation_point, &ignore_error!(PublicKey::from_secret_key(&self.secp_ctx, &htlc_base_key)))))
                                                },
                                                KeyStorage::SigsMode { 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,
                                                Some(their_htlc_base_key) => ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, revocation_point, &their_htlc_base_key)),
                                        };

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

                                        for (idx, htlc) in per_commitment_data.iter().enumerate() {
                                                if let Some(payment_preimage) = self.payment_preimages.get(&htlc.payment_hash) {
                                                        let input = TxIn {
                                                                prev_hash: commitment_txid,
                                                                prev_index: htlc.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[htlc.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.to_vec());
                                                                txn_to_broadcast.push(single_htlc_tx);
                                                        }
                                                }
                                        }

                                        if inputs.is_empty() { return txn_to_broadcast; } // 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.to_vec());
                                        }

                                        txn_to_broadcast.push(spend_tx);
                                }
                        }
                } else {
                        //TODO: For each input check if its in our remote_commitment_txn_on_chain map!
                }

                txn_to_broadcast
        }

        fn broadcast_by_local_state(&self, local_tx: &LocalSignedTx) -> Vec<Transaction> {
                let mut res = Vec::with_capacity(local_tx.htlc_outputs.len());

                for &(ref htlc, ref their_sig, ref our_sig) in local_tx.htlc_outputs.iter() {
                        if htlc.offered {
                                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(&self.secp_ctx).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(&self.secp_ctx).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_vec());

                                res.push(htlc_timeout_tx);
                        } else {
                                if let Some(payment_preimage) = self.payment_preimages.get(&htlc.payment_hash) {
                                        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(&self.secp_ctx).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(&self.secp_ctx).to_vec());
                                        htlc_success_tx.input[0].witness[2].push(SigHashType::All as u8);

                                        htlc_success_tx.input[0].witness.push(payment_preimage.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_vec());

                                        res.push(htlc_success_tx);
                                }
                        }
                }

                res
        }

        /// 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> {
                let commitment_txid = tx.txid();
                if let &Some(ref local_tx) = &self.current_local_signed_commitment_tx {
                        if local_tx.txid == commitment_txid {
                                return self.broadcast_by_local_state(local_tx);
                        }
                }
                if let &Some(ref local_tx) = &self.prev_local_signed_commitment_tx {
                        if local_tx.txid == commitment_txid {
                                return self.broadcast_by_local_state(local_tx);
                        }
                }
                Vec::new()
        }

        fn block_connected(&self, txn_matched: &[&Transaction], height: u32, broadcaster: &BroadcasterInterface) {
                for tx in txn_matched {
                        for txin in tx.input.iter() {
                                if self.funding_txo.is_none() || (txin.prev_hash == self.funding_txo.unwrap().txid && txin.prev_index == self.funding_txo.unwrap().index as u32) {
                                        let mut txn = self.check_spend_remote_transaction(tx, height);
                                        if txn.is_empty() {
                                                txn = self.check_spend_local_transaction(tx, height);
                                        }
                                        for tx in txn.iter() {
                                                broadcaster.broadcast_transaction(tx);
                                        }
                                }
                        }
                }
                if let Some(ref cur_local_tx) = self.current_local_signed_commitment_tx {
                        let mut needs_broadcast = false;
                        for &(ref htlc, _, _) in cur_local_tx.htlc_outputs.iter() {
                                if htlc.cltv_expiry <= height + CLTV_CLAIM_BUFFER {
                                        if htlc.offered || self.payment_preimages.contains_key(&htlc.payment_hash) {
                                                needs_broadcast = true;
                                        }
                                }
                        }

                        if needs_broadcast {
                                broadcaster.broadcast_transaction(&cur_local_tx.tx);
                                for tx in self.broadcast_by_local_state(&cur_local_tx) {
                                        broadcaster.broadcast_transaction(&tx);
                                }
                        }
                }
        }

        pub fn would_broadcast_at_height(&self, height: u32) -> bool {
                if let Some(ref cur_local_tx) = self.current_local_signed_commitment_tx {
                        for &(ref htlc, _, _) in cur_local_tx.htlc_outputs.iter() {
                                if htlc.cltv_expiry <= height + CLTV_CLAIM_BUFFER {
                                        if htlc.offered || self.payment_preimages.contains_key(&htlc.payment_hash) {
                                                return true;
                                        }
                                }
                        }
                }
                false
        }
}

#[cfg(test)]
mod tests {
        use bitcoin::util::misc::hex_bytes;
        use bitcoin::blockdata::script::Script;
        use bitcoin::blockdata::transaction::Transaction;
        use crypto::digest::Digest;
        use ln::channelmonitor::ChannelMonitor;
        use ln::chan_utils::{HTLCOutputInCommitment, TxCreationKeys};
        use util::sha2::Sha256;
        use secp256k1::key::{SecretKey,PublicKey};
        use secp256k1::{Secp256k1, Signature};
        use rand::{thread_rng,Rng};

        #[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();

                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_err());
                        };
                }

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

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c65716add7aa98ba7acb236352d665cab17345fe45b55fb879ff80e6bd0c41dd").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("969660042a28f32d9be17344e09374b379962d03db1574df5a8a5a47e19ce3f2").unwrap());
                        monitor.provide_secret(281474976710650, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("a5a64476122ca0925fb344bdc1854c1c0a59fc614298e50a33e331980a220f32").unwrap());
                        monitor.provide_secret(281474976710649, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("05cde6323d949933f7f7b78776bcc1ea6d9b31447732e3802e1f7ac44b650e17").unwrap());
                        monitor.provide_secret(281474976710648, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();
                }

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

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("02a40c85b6f28da08dfdbe0926c53fab2de6d28c10301f8f7c4073d5e42e3148").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710654, secrets.last().unwrap().clone(), None).unwrap_err().err,
                                        "Previous secret did not match new one");
                }

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

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("02a40c85b6f28da08dfdbe0926c53fab2de6d28c10301f8f7c4073d5e42e3148").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("dddc3a8d14fddf2b68fa8c7fbad2748274937479dd0f8930d5ebb4ab6bd866a3").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710652, secrets.last().unwrap().clone(), None).unwrap_err().err,
                                        "Previous secret did not match new one");
                }

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

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c51a18b13e8527e579ec56365482c62f180b7d5760b46e9477dae59e87ed423a").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710652, secrets.last().unwrap().clone(), None).unwrap_err().err,
                                        "Previous secret did not match new one");
                }

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

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("02a40c85b6f28da08dfdbe0926c53fab2de6d28c10301f8f7c4073d5e42e3148").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("dddc3a8d14fddf2b68fa8c7fbad2748274937479dd0f8930d5ebb4ab6bd866a3").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c51a18b13e8527e579ec56365482c62f180b7d5760b46e9477dae59e87ed423a").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("ba65d7b0ef55a3ba300d4e87af29868f394f8f138d78a7011669c79b37b936f4").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c65716add7aa98ba7acb236352d665cab17345fe45b55fb879ff80e6bd0c41dd").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("969660042a28f32d9be17344e09374b379962d03db1574df5a8a5a47e19ce3f2").unwrap());
                        monitor.provide_secret(281474976710650, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("a5a64476122ca0925fb344bdc1854c1c0a59fc614298e50a33e331980a220f32").unwrap());
                        monitor.provide_secret(281474976710649, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("05cde6323d949933f7f7b78776bcc1ea6d9b31447732e3802e1f7ac44b650e17").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710648, secrets.last().unwrap().clone(), None).unwrap_err().err,
                                        "Previous secret did not match new one");
                }

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

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("631373ad5f9ef654bb3dade742d09504c567edd24320d2fcd68e3cc47e2ff6a6").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("969660042a28f32d9be17344e09374b379962d03db1574df5a8a5a47e19ce3f2").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710650, secrets.last().unwrap().clone(), None).unwrap_err().err,
                                        "Previous secret did not match new one");
                }

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

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("631373ad5f9ef654bb3dade742d09504c567edd24320d2fcd68e3cc47e2ff6a6").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("b7e76a83668bde38b373970155c868a653304308f9896692f904a23731224bb1").unwrap());
                        monitor.provide_secret(281474976710650, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("a5a64476122ca0925fb344bdc1854c1c0a59fc614298e50a33e331980a220f32").unwrap());
                        monitor.provide_secret(281474976710649, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("05cde6323d949933f7f7b78776bcc1ea6d9b31447732e3802e1f7ac44b650e17").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710648, secrets.last().unwrap().clone(), None).unwrap_err().err,
                                        "Previous secret did not match new one");
                }

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

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c65716add7aa98ba7acb236352d665cab17345fe45b55fb879ff80e6bd0c41dd").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("969660042a28f32d9be17344e09374b379962d03db1574df5a8a5a47e19ce3f2").unwrap());
                        monitor.provide_secret(281474976710650, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("e7971de736e01da8ed58b94c2fc216cb1dca9e326f3a96e7194fe8ea8af6c0a3").unwrap());
                        monitor.provide_secret(281474976710649, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("05cde6323d949933f7f7b78776bcc1ea6d9b31447732e3802e1f7ac44b650e17").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710648, secrets.last().unwrap().clone(), None).unwrap_err().err,
                                        "Previous secret did not match new one");
                }

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

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                        monitor.provide_secret(281474976710655, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                        monitor.provide_secret(281474976710654, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                        monitor.provide_secret(281474976710653, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                        monitor.provide_secret(281474976710652, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("c65716add7aa98ba7acb236352d665cab17345fe45b55fb879ff80e6bd0c41dd").unwrap());
                        monitor.provide_secret(281474976710651, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("969660042a28f32d9be17344e09374b379962d03db1574df5a8a5a47e19ce3f2").unwrap());
                        monitor.provide_secret(281474976710650, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("a5a64476122ca0925fb344bdc1854c1c0a59fc614298e50a33e331980a220f32").unwrap());
                        monitor.provide_secret(281474976710649, secrets.last().unwrap().clone(), None).unwrap();
                        test_secrets!();

                        secrets.push([0; 32]);
                        secrets.last_mut().unwrap()[0..32].clone_from_slice(&hex_bytes("a7efbc61aac46d34f77778bac22c8a20c6a46ca460addc49009bda875ec88fa4").unwrap());
                        assert_eq!(monitor.provide_secret(281474976710648, secrets.last().unwrap().clone(), None).unwrap_err().err,
                                        "Previous secret did not match new one");
                }
        }

        #[test]
        fn test_prune_preimages() {
                let secp_ctx = Secp256k1::new();
                let dummy_sig = Signature::from_der(&secp_ctx, &hex_bytes("3045022100fa86fa9a36a8cd6a7bb8f06a541787d51371d067951a9461d5404de6b928782e02201c8b7c334c10aed8976a3a465be9a28abff4cb23acbf00022295b378ce1fa3cd").unwrap()[..]).unwrap();

                macro_rules! dummy_keys {
                        () => {
                                TxCreationKeys {
                                        per_commitment_point: PublicKey::new(),
                                        revocation_key: PublicKey::new(),
                                        a_htlc_key: PublicKey::new(),
                                        b_htlc_key: PublicKey::new(),
                                        a_delayed_payment_key: PublicKey::new(),
                                        b_payment_key: PublicKey::new(),
                                }
                        }
                }
                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 = [0; 32];
                                rng.fill_bytes(&mut preimage);
                                let mut sha = Sha256::new();
                                sha.input(&preimage);
                                let mut hash = [0; 32];
                                sha.result(&mut hash);
                                preimages.push((preimage, hash));
                        }
                }

                macro_rules! preimages_slice_to_htlc_outputs {
                        ($preimages_slice: expr) => {
                                {
                                        let mut res = Vec::new();
                                        for (idx, preimage) in $preimages_slice.iter().enumerate() {
                                                res.push(HTLCOutputInCommitment {
                                                        offered: true,
                                                        amount_msat: 0,
                                                        cltv_expiry: 0,
                                                        payment_hash: preimage.1.clone(),
                                                        transaction_output_index: idx as u32,
                                                });
                                        }
                                        res
                                }
                        }
                }
                macro_rules! preimages_to_local_htlcs {
                        ($preimages_slice: expr) => {
                                {
                                        let mut inp = preimages_slice_to_htlc_outputs!($preimages_slice);
                                        let res: Vec<_> = inp.drain(..).map(|e| { (e, dummy_sig.clone(), dummy_sig.clone()) }).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(&secp_ctx, &[42; 32]).unwrap(), &PublicKey::new(), &SecretKey::from_slice(&secp_ctx, &[43; 32]).unwrap(), 0, Script::new());
                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);
                monitor.provide_latest_remote_commitment_tx_info(&dummy_tx, preimages_slice_to_htlc_outputs!(preimages[15..20]), 281474976710654);
                monitor.provide_latest_remote_commitment_tx_info(&dummy_tx, preimages_slice_to_htlc_outputs!(preimages[17..20]), 281474976710653);
                monitor.provide_latest_remote_commitment_tx_info(&dummy_tx, preimages_slice_to_htlc_outputs!(preimages[18..20]), 281474976710652);
                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_bytes("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap());
                monitor.provide_secret(281474976710655, secret.clone(), None).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_bytes("c7518c8ae4660ed02894df8976fa1a3659c1a8b4b5bec0c4b872abeba4cb8964").unwrap());
                monitor.provide_secret(281474976710654, secret.clone(), None).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_bytes("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                monitor.provide_secret(281474976710653, secret.clone(), None).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_bytes("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                monitor.provide_secret(281474976710652, secret.clone(), None).unwrap();
                assert_eq!(monitor.payment_preimages.len(), 5);
                test_preimages_exist!(&preimages[0..5], monitor);
        }

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