Merge pull request #646 from naumenkogs/2020-06-router-mpp
[rust-lightning] / lightning / src / ln / channel.rs
index 3c8be717f3237edc56297d559c806bdb96d80780..633652222d11352f64be2f1f13a75d543e07eca4 100644 (file)
@@ -14,7 +14,7 @@ use bitcoin::blockdata::opcodes;
 use bitcoin::util::bip143;
 use bitcoin::consensus::encode;
 
-use bitcoin::hashes::{Hash, HashEngine};
+use bitcoin::hashes::Hash;
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hash_types::{Txid, BlockHash, WPubkeyHash};
 
@@ -26,14 +26,14 @@ use ln::features::{ChannelFeatures, InitFeatures};
 use ln::msgs;
 use ln::msgs::{DecodeError, OptionalField, DataLossProtect};
 use ln::channelmanager::{PendingHTLCStatus, HTLCSource, HTLCFailReason, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, PaymentPreimage, PaymentHash, BREAKDOWN_TIMEOUT, MAX_LOCAL_BREAKDOWN_TIMEOUT};
-use ln::chan_utils::{CounterpartyCommitmentSecrets, HolderCommitmentTransaction, TxCreationKeys, HTLCOutputInCommitment, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT, make_funding_redeemscript, ChannelPublicKeys, PreCalculatedTxCreationKeys};
+use ln::chan_utils::{CounterpartyCommitmentSecrets, TxCreationKeys, HTLCOutputInCommitment, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT, make_funding_redeemscript, ChannelPublicKeys, CommitmentTransaction, HolderCommitmentTransaction, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, MAX_HTLCS, get_commitment_transaction_number_obscure_factor};
 use ln::chan_utils;
 use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
 use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, HTLC_FAIL_BACK_BUFFER};
 use chain::transaction::{OutPoint, TransactionData};
-use chain::keysinterface::{ChannelKeys, KeysInterface};
+use chain::keysinterface::{Sign, KeysInterface};
 use util::transaction_utils;
-use util::ser::{Readable, Writeable, Writer};
+use util::ser::{Readable, ReadableArgs, Writeable, Writer, VecWriter};
 use util::logger::Logger;
 use util::errors::APIError;
 use util::config::{UserConfig,ChannelConfig};
@@ -42,7 +42,10 @@ use std;
 use std::default::Default;
 use std::{cmp,mem,fmt};
 use std::ops::Deref;
+#[cfg(any(test, feature = "fuzztarget"))]
+use std::sync::Mutex;
 use bitcoin::hashes::hex::ToHex;
+use bitcoin::blockdata::opcodes::all::OP_PUSHBYTES_0;
 
 #[cfg(test)]
 pub struct ChannelValueStat {
@@ -111,7 +114,7 @@ enum InboundHTLCState {
        /// anyway). That said, ChannelMonitor does this for us (see
        /// ChannelMonitor::would_broadcast_at_height) so we actually remove the HTLC from our own
        /// local state before then, once we're sure that the next commitment_signed and
-       /// ChannelMonitor::provide_latest_local_commitment_tx_info will not include this HTLC.
+       /// ChannelMonitor::provide_latest_local_commitment_tx will not include this HTLC.
        LocalRemoved(InboundHTLCRemovalReason),
 }
 
@@ -242,7 +245,7 @@ enum ChannelState {
 const BOTH_SIDES_SHUTDOWN_MASK: u32 = ChannelState::LocalShutdownSent as u32 | ChannelState::RemoteShutdownSent as u32;
 const MULTI_STATE_FLAGS: u32 = BOTH_SIDES_SHUTDOWN_MASK | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32;
 
-const INITIAL_COMMITMENT_NUMBER: u64 = (1 << 48) - 1;
+pub const INITIAL_COMMITMENT_NUMBER: u64 = (1 << 48) - 1;
 
 /// Liveness is called to fluctuate given peer disconnecton/monitor failures/closing.
 /// If channel is public, network should have a liveness view announced by us on a
@@ -258,6 +261,27 @@ enum UpdateStatus {
        DisabledStaged,
 }
 
+/// An enum indicating whether the local or remote side offered a given HTLC.
+enum HTLCInitiator {
+       LocalOffered,
+       RemoteOffered,
+}
+
+/// Used when calculating whether we or the remote can afford an additional HTLC.
+struct HTLCCandidate {
+       amount_msat: u64,
+       origin: HTLCInitiator,
+}
+
+impl HTLCCandidate {
+       fn new(amount_msat: u64, origin: HTLCInitiator) -> Self {
+               Self {
+                       amount_msat,
+                       origin,
+               }
+       }
+}
+
 // TODO: We should refactor this to be an Inbound/OutboundChannel until initial setup handshaking
 // has been completed, and then turn into a Channel to get compiler-time enforcement of things like
 // calling channel_id() before we're set up or things like get_outbound_funding_signed on an
@@ -265,23 +289,19 @@ enum UpdateStatus {
 //
 // Holder designates channel data owned for the benefice of the user client.
 // Counterparty designates channel data owned by the another channel participant entity.
-pub(super) struct Channel<ChanSigner: ChannelKeys> {
+pub(super) struct Channel<Signer: Sign> {
        config: ChannelConfig,
 
        user_id: u64,
 
        channel_id: [u8; 32],
        channel_state: u32,
-       channel_outbound: bool,
        secp_ctx: Secp256k1<secp256k1::All>,
        channel_value_satoshis: u64,
 
        latest_monitor_update_id: u64,
 
-       #[cfg(not(test))]
-       holder_keys: ChanSigner,
-       #[cfg(test)]
-       pub(super) holder_keys: ChanSigner,
+       holder_signer: Signer,
        shutdown_pubkey: PublicKey,
        destination_script: Script,
 
@@ -342,8 +362,6 @@ pub(super) struct Channel<ChanSigner: ChannelKeys> {
 
        last_sent_closing_fee: Option<(u32, u64, Signature)>, // (feerate, fee, holder_sig)
 
-       funding_txo: Option<OutPoint>,
-
        /// The hash of the block in which the funding transaction reached our CONF_TARGET. We use this
        /// to detect unconfirmation after a serialize-unserialize roundtrip where we may not see a full
        /// series of block_connected/block_disconnected calls. Obviously this is not a guarantee as we
@@ -370,8 +388,6 @@ pub(super) struct Channel<ChanSigner: ChannelKeys> {
        // get_holder_selected_channel_reserve_satoshis(channel_value_sats: u64): u64
        counterparty_htlc_minimum_msat: u64,
        holder_htlc_minimum_msat: u64,
-       counterparty_selected_contest_delay: u16,
-       holder_selected_contest_delay: u16,
        #[cfg(test)]
        pub counterparty_max_accepted_htlcs: u16,
        #[cfg(not(test))]
@@ -379,7 +395,7 @@ pub(super) struct Channel<ChanSigner: ChannelKeys> {
        //implied by OUR_MAX_HTLCS: max_accepted_htlcs: u16,
        minimum_depth: u32,
 
-       counterparty_pubkeys: Option<ChannelPublicKeys>,
+       pub(crate) channel_transaction_parameters: ChannelTransactionParameters,
 
        counterparty_cur_commitment_point: Option<PublicKey>,
 
@@ -391,6 +407,24 @@ pub(super) struct Channel<ChanSigner: ChannelKeys> {
        commitment_secrets: CounterpartyCommitmentSecrets,
 
        network_sync: UpdateStatus,
+
+       // We save these values so we can make sure `next_local_commit_tx_fee_msat` and
+       // `next_remote_commit_tx_fee_msat` properly predict what the next commitment transaction fee will
+       // be, by comparing the cached values to the fee of the tranaction generated by
+       // `build_commitment_transaction`.
+       #[cfg(any(test, feature = "fuzztarget"))]
+       next_local_commitment_tx_fee_info_cached: Mutex<Option<CommitmentTxInfoCached>>,
+       #[cfg(any(test, feature = "fuzztarget"))]
+       next_remote_commitment_tx_fee_info_cached: Mutex<Option<CommitmentTxInfoCached>>,
+}
+
+#[cfg(any(test, feature = "fuzztarget"))]
+struct CommitmentTxInfoCached {
+       fee: u64,
+       total_pending_htlcs: usize,
+       next_holder_htlc_id: u64,
+       next_counterparty_htlc_id: u64,
+       feerate: u32,
 }
 
 pub const OUR_MAX_HTLCS: u16 = 50; //TODO
@@ -442,7 +476,7 @@ macro_rules! secp_check {
        };
 }
 
-impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
+impl<Signer: Sign> Channel<Signer> {
        // Convert constants + channel value to limits:
        fn get_holder_max_htlc_value_in_flight_msat(channel_value_satoshis: u64) -> u64 {
                channel_value_satoshis * 1000 / 10 //TODO
@@ -462,12 +496,13 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        }
 
        // Constructors:
-       pub fn new_outbound<K: Deref, F: Deref>(fee_estimator: &F, keys_provider: &K, counterparty_node_id: PublicKey, channel_value_satoshis: u64, push_msat: u64, user_id: u64, config: &UserConfig) -> Result<Channel<ChanSigner>, APIError>
-       where K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+       pub fn new_outbound<K: Deref, F: Deref>(fee_estimator: &F, keys_provider: &K, counterparty_node_id: PublicKey, channel_value_satoshis: u64, push_msat: u64, user_id: u64, config: &UserConfig) -> Result<Channel<Signer>, APIError>
+       where K::Target: KeysInterface<Signer = Signer>,
              F::Target: FeeEstimator,
        {
                let holder_selected_contest_delay = config.own_channel_config.our_to_self_delay;
-               let chan_keys = keys_provider.get_channel_keys(false, channel_value_satoshis);
+               let holder_signer = keys_provider.get_channel_signer(false, channel_value_satoshis);
+               let pubkeys = holder_signer.pubkeys().clone();
 
                if channel_value_satoshis >= MAX_FUNDING_SATOSHIS {
                        return Err(APIError::APIMisuseError{err: format!("funding_value must be smaller than {}, it was {}", MAX_FUNDING_SATOSHIS, channel_value_satoshis)});
@@ -480,25 +515,27 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        return Err(APIError::APIMisuseError {err: format!("Configured with an unreasonable our_to_self_delay ({}) putting user funds at risks", holder_selected_contest_delay)});
                }
                let background_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
-               if Channel::<ChanSigner>::get_holder_selected_channel_reserve_satoshis(channel_value_satoshis) < Channel::<ChanSigner>::derive_holder_dust_limit_satoshis(background_feerate) {
+               if Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(channel_value_satoshis) < Channel::<Signer>::derive_holder_dust_limit_satoshis(background_feerate) {
                        return Err(APIError::FeeRateTooHigh{err: format!("Not enough reserve above dust limit can be found at current fee rate({})", background_feerate), feerate: background_feerate});
                }
 
                let feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Normal);
 
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&keys_provider.get_secure_random_bytes());
+
                Ok(Channel {
                        user_id,
                        config: config.channel_options.clone(),
 
                        channel_id: keys_provider.get_secure_random_bytes(),
                        channel_state: ChannelState::OurInitSent as u32,
-                       channel_outbound: true,
-                       secp_ctx: Secp256k1::new(),
+                       secp_ctx,
                        channel_value_satoshis,
 
                        latest_monitor_update_id: 0,
 
-                       holder_keys: chan_keys,
+                       holder_signer,
                        shutdown_pubkey: keys_provider.get_shutdown_pubkey(),
                        destination_script: keys_provider.get_destination_script(),
 
@@ -530,7 +567,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
                        last_sent_closing_fee: None,
 
-                       funding_txo: None,
                        funding_tx_confirmed_in: None,
                        short_channel_id: None,
                        last_block_connected: Default::default(),
@@ -538,17 +574,21 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
                        feerate_per_kw: feerate,
                        counterparty_dust_limit_satoshis: 0,
-                       holder_dust_limit_satoshis: Channel::<ChanSigner>::derive_holder_dust_limit_satoshis(background_feerate),
+                       holder_dust_limit_satoshis: Channel::<Signer>::derive_holder_dust_limit_satoshis(background_feerate),
                        counterparty_max_htlc_value_in_flight_msat: 0,
                        counterparty_selected_channel_reserve_satoshis: 0,
                        counterparty_htlc_minimum_msat: 0,
                        holder_htlc_minimum_msat: if config.own_channel_config.our_htlc_minimum_msat == 0 { 1 } else { config.own_channel_config.our_htlc_minimum_msat },
-                       counterparty_selected_contest_delay: 0,
-                       holder_selected_contest_delay,
                        counterparty_max_accepted_htlcs: 0,
                        minimum_depth: 0, // Filled in in accept_channel
 
-                       counterparty_pubkeys: None,
+                       channel_transaction_parameters: ChannelTransactionParameters {
+                               holder_pubkeys: pubkeys,
+                               holder_selected_contest_delay: config.own_channel_config.our_to_self_delay,
+                               is_outbound_from_holder: true,
+                               counterparty_parameters: None,
+                               funding_outpoint: None
+                       },
                        counterparty_cur_commitment_point: None,
 
                        counterparty_prev_commitment_point: None,
@@ -559,6 +599,11 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        commitment_secrets: CounterpartyCommitmentSecrets::new(),
 
                        network_sync: UpdateStatus::Fresh,
+
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       next_local_commitment_tx_fee_info_cached: Mutex::new(None),
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
                })
        }
 
@@ -578,11 +623,12 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
        /// Creates a new channel from a remote sides' request for one.
        /// Assumes chain_hash has already been checked and corresponds with what we expect!
-       pub fn new_from_req<K: Deref, F: Deref>(fee_estimator: &F, keys_provider: &K, counterparty_node_id: PublicKey, their_features: InitFeatures, msg: &msgs::OpenChannel, user_id: u64, config: &UserConfig) -> Result<Channel<ChanSigner>, ChannelError>
-               where K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+       pub fn new_from_req<K: Deref, F: Deref>(fee_estimator: &F, keys_provider: &K, counterparty_node_id: PublicKey, their_features: InitFeatures, msg: &msgs::OpenChannel, user_id: u64, config: &UserConfig) -> Result<Channel<Signer>, ChannelError>
+               where K::Target: KeysInterface<Signer = Signer>,
           F::Target: FeeEstimator
        {
-               let mut chan_keys = keys_provider.get_channel_keys(true, msg.funding_satoshis);
+               let holder_signer = keys_provider.get_channel_signer(true, msg.funding_satoshis);
+               let pubkeys = holder_signer.pubkeys().clone();
                let counterparty_pubkeys = ChannelPublicKeys {
                        funding_pubkey: msg.funding_pubkey,
                        revocation_basepoint: msg.revocation_basepoint,
@@ -590,7 +636,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        delayed_payment_basepoint: msg.delayed_payment_basepoint,
                        htlc_basepoint: msg.htlc_basepoint
                };
-               chan_keys.on_accept(&counterparty_pubkeys, msg.to_self_delay, config.own_channel_config.our_to_self_delay);
                let mut local_config = (*config).channel_options.clone();
 
                if config.own_channel_config.our_to_self_delay < BREAKDOWN_TIMEOUT {
@@ -618,7 +663,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                if msg.htlc_minimum_msat >= full_channel_value_msat {
                        return Err(ChannelError::Close(format!("Minimum htlc value ({}) was larger than full channel value ({})", msg.htlc_minimum_msat, full_channel_value_msat)));
                }
-               Channel::<ChanSigner>::check_remote_fee(fee_estimator, msg.feerate_per_kw)?;
+               Channel::<Signer>::check_remote_fee(fee_estimator, msg.feerate_per_kw)?;
 
                let max_counterparty_selected_contest_delay = u16::min(config.peer_channel_config_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
                if msg.to_self_delay > max_counterparty_selected_contest_delay {
@@ -627,8 +672,8 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                if msg.max_accepted_htlcs < 1 {
                        return Err(ChannelError::Close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
                }
-               if msg.max_accepted_htlcs > 483 {
-                       return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than 483", msg.max_accepted_htlcs)));
+               if msg.max_accepted_htlcs > MAX_HTLCS {
+                       return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than {}", msg.max_accepted_htlcs, MAX_HTLCS)));
                }
 
                // Now check against optional parameters as set by config...
@@ -667,8 +712,8 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
                let background_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
 
-               let holder_dust_limit_satoshis = Channel::<ChanSigner>::derive_holder_dust_limit_satoshis(background_feerate);
-               let holder_selected_channel_reserve_satoshis = Channel::<ChanSigner>::get_holder_selected_channel_reserve_satoshis(msg.funding_satoshis);
+               let holder_dust_limit_satoshis = Channel::<Signer>::derive_holder_dust_limit_satoshis(background_feerate);
+               let holder_selected_channel_reserve_satoshis = Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(msg.funding_satoshis);
                if holder_selected_channel_reserve_satoshis < holder_dust_limit_satoshis {
                        return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({}). dust_limit_satoshis is ({}).", holder_selected_channel_reserve_satoshis, holder_dust_limit_satoshis)));
                }
@@ -696,15 +741,14 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
                        match &msg.shutdown_scriptpubkey {
                                &OptionalField::Present(ref script) => {
-                                       // Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. We enforce it while receiving shutdown msg
-                                       if script.is_p2pkh() || script.is_p2sh() || script.is_v0_p2wsh() || script.is_v0_p2wpkh() {
-                                               Some(script.clone())
                                        // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
-                                       } else if script.len() == 0 {
+                                       if script.len() == 0 {
                                                None
                                        // Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. Fail the channel
-                                       } else {
+                                       } else if is_unsupported_shutdown_script(&their_features, script) {
                                                return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided a non-accepted scriptpubkey format. script: ({})", script.to_bytes().to_hex())));
+                                       } else {
+                                               Some(script.clone())
                                        }
                                },
                                // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
@@ -714,18 +758,20 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        }
                } else { None };
 
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&keys_provider.get_secure_random_bytes());
+
                let chan = Channel {
                        user_id,
                        config: local_config,
 
                        channel_id: msg.temporary_channel_id,
                        channel_state: (ChannelState::OurInitSent as u32) | (ChannelState::TheirInitSent as u32),
-                       channel_outbound: false,
-                       secp_ctx: Secp256k1::new(),
+                       secp_ctx,
 
                        latest_monitor_update_id: 0,
 
-                       holder_keys: chan_keys,
+                       holder_signer,
                        shutdown_pubkey: keys_provider.get_shutdown_pubkey(),
                        destination_script: keys_provider.get_destination_script(),
 
@@ -757,7 +803,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
                        last_sent_closing_fee: None,
 
-                       funding_txo: None,
                        funding_tx_confirmed_in: None,
                        short_channel_id: None,
                        last_block_connected: Default::default(),
@@ -771,12 +816,19 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        counterparty_selected_channel_reserve_satoshis: msg.channel_reserve_satoshis,
                        counterparty_htlc_minimum_msat: msg.htlc_minimum_msat,
                        holder_htlc_minimum_msat: if config.own_channel_config.our_htlc_minimum_msat == 0 { 1 } else { config.own_channel_config.our_htlc_minimum_msat },
-                       counterparty_selected_contest_delay: msg.to_self_delay,
-                       holder_selected_contest_delay: config.own_channel_config.our_to_self_delay,
                        counterparty_max_accepted_htlcs: msg.max_accepted_htlcs,
                        minimum_depth: config.own_channel_config.minimum_depth,
 
-                       counterparty_pubkeys: Some(counterparty_pubkeys),
+                       channel_transaction_parameters: ChannelTransactionParameters {
+                               holder_pubkeys: pubkeys,
+                               holder_selected_contest_delay: config.own_channel_config.our_to_self_delay,
+                               is_outbound_from_holder: false,
+                               counterparty_parameters: Some(CounterpartyChannelTransactionParameters {
+                                       selected_contest_delay: msg.to_self_delay,
+                                       pubkeys: counterparty_pubkeys,
+                               }),
+                               funding_outpoint: None
+                       },
                        counterparty_cur_commitment_point: Some(msg.first_per_commitment_point),
 
                        counterparty_prev_commitment_point: None,
@@ -787,34 +839,16 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        commitment_secrets: CounterpartyCommitmentSecrets::new(),
 
                        network_sync: UpdateStatus::Fresh,
+
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       next_local_commitment_tx_fee_info_cached: Mutex::new(None),
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
                };
 
                Ok(chan)
        }
 
-       // Utilities to build transactions:
-
-       fn get_commitment_transaction_number_obscure_factor(&self) -> u64 {
-               let mut sha = Sha256::engine();
-
-               let counterparty_payment_point = &self.counterparty_pubkeys.as_ref().unwrap().payment_point.serialize();
-               if self.channel_outbound {
-                       sha.input(&self.holder_keys.pubkeys().payment_point.serialize());
-                       sha.input(counterparty_payment_point);
-               } else {
-                       sha.input(counterparty_payment_point);
-                       sha.input(&self.holder_keys.pubkeys().payment_point.serialize());
-               }
-               let res = Sha256::from_engine(sha).into_inner();
-
-               ((res[26] as u64) << 5*8) |
-               ((res[27] as u64) << 4*8) |
-               ((res[28] as u64) << 3*8) |
-               ((res[29] as u64) << 2*8) |
-               ((res[30] as u64) << 1*8) |
-               ((res[31] as u64) << 0*8)
-       }
-
        /// Transaction nomenclature is somewhat confusing here as there are many different cases - a
        /// transaction is referred to as "a's transaction" implying that a will be able to broadcast
        /// the transaction. Thus, b will generally be sending a signature over such a transaction to
@@ -828,34 +862,22 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        /// have not yet committed it. Such HTLCs will only be included in transactions which are being
        /// generated by the peer which proposed adding the HTLCs, and thus we need to understand both
        /// which peer generated this transaction and "to whom" this transaction flows.
-       /// Returns (the transaction built, the number of HTLC outputs which were present in the
+       /// Returns (the transaction info, the number of HTLC outputs which were present in the
        /// transaction, the list of HTLCs which were not ignored when building the transaction).
        /// Note that below-dust HTLCs are included in the third return value, but not the second, and
        /// sources are provided only for outbound HTLCs in the third return value.
        #[inline]
-       fn build_commitment_transaction<L: Deref>(&self, commitment_number: u64, keys: &TxCreationKeys, local: bool, generated_by_local: bool, feerate_per_kw: u32, logger: &L) -> (Transaction, usize, Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)>) where L::Target: Logger {
-               let obscured_commitment_transaction_number = self.get_commitment_transaction_number_obscure_factor() ^ (INITIAL_COMMITMENT_NUMBER - commitment_number);
-
-               let txins = {
-                       let mut ins: Vec<TxIn> = Vec::new();
-                       ins.push(TxIn {
-                               previous_output: self.funding_txo.unwrap().into_bitcoin_outpoint(),
-                               script_sig: Script::new(),
-                               sequence: ((0x80 as u32) << 8*3) | ((obscured_commitment_transaction_number >> 3*8) as u32),
-                               witness: Vec::new(),
-                       });
-                       ins
-               };
-
-               let mut txouts: Vec<(TxOut, Option<(HTLCOutputInCommitment, Option<&HTLCSource>)>)> = Vec::with_capacity(self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len() + 2);
+       fn build_commitment_transaction<L: Deref>(&self, commitment_number: u64, keys: &TxCreationKeys, local: bool, generated_by_local: bool, feerate_per_kw: u32, logger: &L) -> (CommitmentTransaction, usize, Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)>) where L::Target: Logger {
                let mut included_dust_htlcs: Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)> = Vec::new();
+               let num_htlcs = self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len();
+               let mut included_non_dust_htlcs: Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)> = Vec::with_capacity(num_htlcs);
 
                let broadcaster_dust_limit_satoshis = if local { self.holder_dust_limit_satoshis } else { self.counterparty_dust_limit_satoshis };
                let mut remote_htlc_total_msat = 0;
                let mut local_htlc_total_msat = 0;
                let mut value_to_self_msat_offset = 0;
 
-               log_trace!(logger, "Building commitment transaction number {} (really {} xor {}) for {}, generated by {} with fee {}...", commitment_number, (INITIAL_COMMITMENT_NUMBER - commitment_number), self.get_commitment_transaction_number_obscure_factor(), if local { "us" } else { "remote" }, if generated_by_local { "us" } else { "remote" }, feerate_per_kw);
+               log_trace!(logger, "Building commitment transaction number {} (really {} xor {}) for {}, generated by {} with fee {}...", commitment_number, (INITIAL_COMMITMENT_NUMBER - commitment_number), get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound()), if local { "us" } else { "remote" }, if generated_by_local { "us" } else { "remote" }, feerate_per_kw);
 
                macro_rules! get_htlc_in_commitment {
                        ($htlc: expr, $offered: expr) => {
@@ -875,10 +897,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                                        let htlc_in_tx = get_htlc_in_commitment!($htlc, true);
                                        if $htlc.amount_msat / 1000 >= broadcaster_dust_limit_satoshis + (feerate_per_kw as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) {
                                                log_trace!(logger, "   ...including {} {} HTLC {} (hash {}) with value {}", if $outbound { "outbound" } else { "inbound" }, $state_name, $htlc.htlc_id, log_bytes!($htlc.payment_hash.0), $htlc.amount_msat);
-                                               txouts.push((TxOut {
-                                                       script_pubkey: chan_utils::get_htlc_redeemscript(&htlc_in_tx, &keys).to_v0_p2wsh(),
-                                                       value: $htlc.amount_msat / 1000
-                                               }, Some((htlc_in_tx, $source))));
+                                               included_non_dust_htlcs.push((htlc_in_tx, $source));
                                        } else {
                                                log_trace!(logger, "   ...including {} {} dust HTLC {} (hash {}) with value {} due to dust limit", if $outbound { "outbound" } else { "inbound" }, $state_name, $htlc.htlc_id, log_bytes!($htlc.payment_hash.0), $htlc.amount_msat);
                                                included_dust_htlcs.push((htlc_in_tx, $source));
@@ -887,10 +906,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                                        let htlc_in_tx = get_htlc_in_commitment!($htlc, false);
                                        if $htlc.amount_msat / 1000 >= broadcaster_dust_limit_satoshis + (feerate_per_kw as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) {
                                                log_trace!(logger, "   ...including {} {} HTLC {} (hash {}) with value {}", if $outbound { "outbound" } else { "inbound" }, $state_name, $htlc.htlc_id, log_bytes!($htlc.payment_hash.0), $htlc.amount_msat);
-                                               txouts.push((TxOut { // "received HTLC output"
-                                                       script_pubkey: chan_utils::get_htlc_redeemscript(&htlc_in_tx, &keys).to_v0_p2wsh(),
-                                                       value: $htlc.amount_msat / 1000
-                                               }, Some((htlc_in_tx, $source))));
+                                               included_non_dust_htlcs.push((htlc_in_tx, $source));
                                        } else {
                                                log_trace!(logger, "   ...including {} {} dust HTLC {} (hash {}) with value {}", if $outbound { "outbound" } else { "inbound" }, $state_name, $htlc.htlc_id, log_bytes!($htlc.payment_hash.0), $htlc.amount_msat);
                                                included_dust_htlcs.push((htlc_in_tx, $source));
@@ -974,77 +990,51 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        };
                        debug_assert!(broadcaster_max_commitment_tx_output.0 <= value_to_self_msat as u64 || value_to_self_msat / 1000 >= self.counterparty_selected_channel_reserve_satoshis as i64);
                        broadcaster_max_commitment_tx_output.0 = cmp::max(broadcaster_max_commitment_tx_output.0, value_to_self_msat as u64);
-                       debug_assert!(broadcaster_max_commitment_tx_output.1 <= value_to_remote_msat as u64 || value_to_remote_msat / 1000 >= Channel::<ChanSigner>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis) as i64);
+                       debug_assert!(broadcaster_max_commitment_tx_output.1 <= value_to_remote_msat as u64 || value_to_remote_msat / 1000 >= Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis) as i64);
                        broadcaster_max_commitment_tx_output.1 = cmp::max(broadcaster_max_commitment_tx_output.1, value_to_remote_msat as u64);
                }
 
-               let total_fee = feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + (txouts.len() as u64) * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000;
-               let (value_to_self, value_to_remote) = if self.channel_outbound {
+               let total_fee = feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + (included_non_dust_htlcs.len() as u64) * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000;
+               let (value_to_self, value_to_remote) = if self.is_outbound() {
                        (value_to_self_msat / 1000 - total_fee as i64, value_to_remote_msat / 1000)
                } else {
                        (value_to_self_msat / 1000, value_to_remote_msat / 1000 - total_fee as i64)
                };
 
-               let value_to_a = if local { value_to_self } else { value_to_remote };
-               let value_to_b = if local { value_to_remote } else { value_to_self };
+               let mut value_to_a = if local { value_to_self } else { value_to_remote };
+               let mut value_to_b = if local { value_to_remote } else { value_to_self };
 
                if value_to_a >= (broadcaster_dust_limit_satoshis as i64) {
                        log_trace!(logger, "   ...including {} output with value {}", if local { "to_local" } else { "to_remote" }, value_to_a);
-                       txouts.push((TxOut {
-                               script_pubkey: chan_utils::get_revokeable_redeemscript(&keys.revocation_key,
-                                                                                      if local { self.counterparty_selected_contest_delay } else { self.holder_selected_contest_delay },
-                                                                                      &keys.broadcaster_delayed_payment_key).to_v0_p2wsh(),
-                               value: value_to_a as u64
-                       }, None));
+               } else {
+                       value_to_a = 0;
                }
 
                if value_to_b >= (broadcaster_dust_limit_satoshis as i64) {
                        log_trace!(logger, "   ...including {} output with value {}", if local { "to_remote" } else { "to_local" }, value_to_b);
-                       let static_payment_pk = if local {
-                               self.counterparty_pubkeys.as_ref().unwrap().payment_point
-                       } else {
-                               self.holder_keys.pubkeys().payment_point
-                       }.serialize();
-                       txouts.push((TxOut {
-                               script_pubkey: Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
-                                                            .push_slice(&WPubkeyHash::hash(&static_payment_pk)[..])
-                                                            .into_script(),
-                               value: value_to_b as u64
-                       }, None));
-               }
-
-               transaction_utils::sort_outputs(&mut txouts, |a, b| {
-                       if let &Some(ref a_htlc) = a {
-                               if let &Some(ref b_htlc) = b {
-                                       a_htlc.0.cltv_expiry.cmp(&b_htlc.0.cltv_expiry)
-                                               // Note that due to hash collisions, we have to have a fallback comparison
-                                               // here for fuzztarget mode (otherwise at least chanmon_fail_consistency
-                                               // may fail)!
-                                               .then(a_htlc.0.payment_hash.0.cmp(&b_htlc.0.payment_hash.0))
-                               // For non-HTLC outputs, if they're copying our SPK we don't really care if we
-                               // close the channel due to mismatches - they're doing something dumb:
-                               } else { cmp::Ordering::Equal }
-                       } else { cmp::Ordering::Equal }
-               });
-
-               let mut outputs: Vec<TxOut> = Vec::with_capacity(txouts.len());
-               let mut htlcs_included: Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)> = Vec::with_capacity(txouts.len() + included_dust_htlcs.len());
-               for (idx, mut out) in txouts.drain(..).enumerate() {
-                       outputs.push(out.0);
-                       if let Some((mut htlc, source_option)) = out.1.take() {
-                               htlc.transaction_output_index = Some(idx as u32);
-                               htlcs_included.push((htlc, source_option));
-                       }
+               } else {
+                       value_to_b = 0;
                }
-               let non_dust_htlc_count = htlcs_included.len();
+
+               let num_nondust_htlcs = included_non_dust_htlcs.len();
+
+               let channel_parameters =
+                       if local { self.channel_transaction_parameters.as_holder_broadcastable() }
+                       else { self.channel_transaction_parameters.as_counterparty_broadcastable() };
+               let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(commitment_number,
+                                                                            value_to_a as u64,
+                                                                            value_to_b as u64,
+                                                                            keys.clone(),
+                                                                            feerate_per_kw,
+                                                                            &mut included_non_dust_htlcs,
+                                                                            &channel_parameters
+               );
+               let mut htlcs_included = included_non_dust_htlcs;
+               // The unwrap is safe, because all non-dust HTLCs have been assigned an output index
+               htlcs_included.sort_unstable_by_key(|h| h.0.transaction_output_index.unwrap());
                htlcs_included.append(&mut included_dust_htlcs);
 
-               (Transaction {
-                       version: 2,
-                       lock_time: ((0x20 as u32) << 8*3) | ((obscured_commitment_transaction_number & 0xffffffu64) as u32),
-                       input: txins,
-                       output: outputs,
-               }, non_dust_htlc_count, htlcs_included)
+               (tx, num_nondust_htlcs, htlcs_included)
        }
 
        #[inline]
@@ -1085,7 +1075,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                let txins = {
                        let mut ins: Vec<TxIn> = Vec::new();
                        ins.push(TxIn {
-                               previous_output: self.funding_txo.unwrap().into_bitcoin_outpoint(),
+                               previous_output: self.funding_outpoint().into_bitcoin_outpoint(),
                                script_sig: Script::new(),
                                sequence: 0xffffffff,
                                witness: Vec::new(),
@@ -1098,14 +1088,14 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                let mut txouts: Vec<(TxOut, ())> = Vec::new();
 
                let mut total_fee_satoshis = proposed_total_fee_satoshis;
-               let value_to_self: i64 = (self.value_to_self_msat as i64) / 1000 - if self.channel_outbound { total_fee_satoshis as i64 } else { 0 };
-               let value_to_remote: i64 = ((self.channel_value_satoshis * 1000 - self.value_to_self_msat) as i64 / 1000) - if self.channel_outbound { 0 } else { total_fee_satoshis as i64 };
+               let value_to_self: i64 = (self.value_to_self_msat as i64) / 1000 - if self.is_outbound() { total_fee_satoshis as i64 } else { 0 };
+               let value_to_remote: i64 = ((self.channel_value_satoshis * 1000 - self.value_to_self_msat) as i64 / 1000) - if self.is_outbound() { 0 } else { total_fee_satoshis as i64 };
 
                if value_to_self < 0 {
-                       assert!(self.channel_outbound);
+                       assert!(self.is_outbound());
                        total_fee_satoshis += (-value_to_self) as u64;
                } else if value_to_remote < 0 {
-                       assert!(!self.channel_outbound);
+                       assert!(!self.is_outbound());
                        total_fee_satoshis += (-value_to_remote) as u64;
                }
 
@@ -1138,6 +1128,10 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                }, total_fee_satoshis)
        }
 
+       fn funding_outpoint(&self) -> OutPoint {
+               self.channel_transaction_parameters.funding_outpoint.unwrap()
+       }
+
        #[inline]
        /// Creates a set of keys for build_commitment_transaction to generate a transaction which our
        /// counterparty will sign (ie DO NOT send signatures over a transaction created by this to
@@ -1145,10 +1139,10 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        /// The result is a transaction which we can revoke broadcastership of (ie a "local" transaction)
        /// TODO Some magic rust shit to compile-time check this?
        fn build_holder_transaction_keys(&self, commitment_number: u64) -> Result<TxCreationKeys, ChannelError> {
-               let per_commitment_point = self.holder_keys.get_per_commitment_point(commitment_number, &self.secp_ctx);
-               let delayed_payment_base = &self.holder_keys.pubkeys().delayed_payment_basepoint;
-               let htlc_basepoint = &self.holder_keys.pubkeys().htlc_basepoint;
-               let counterparty_pubkeys = self.counterparty_pubkeys.as_ref().unwrap();
+               let per_commitment_point = self.holder_signer.get_per_commitment_point(commitment_number, &self.secp_ctx);
+               let delayed_payment_base = &self.get_holder_pubkeys().delayed_payment_basepoint;
+               let htlc_basepoint = &self.get_holder_pubkeys().htlc_basepoint;
+               let counterparty_pubkeys = self.get_counterparty_pubkeys();
 
                Ok(secp_check!(TxCreationKeys::derive_new(&self.secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &counterparty_pubkeys.revocation_basepoint, &counterparty_pubkeys.htlc_basepoint), "Local tx keys generation got bogus keys".to_owned()))
        }
@@ -1160,9 +1154,9 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        fn build_remote_transaction_keys(&self) -> Result<TxCreationKeys, ChannelError> {
                //TODO: Ensure that the payment_key derived here ends up in the library users' wallet as we
                //may see payments to it!
-               let revocation_basepoint = &self.holder_keys.pubkeys().revocation_basepoint;
-               let htlc_basepoint = &self.holder_keys.pubkeys().htlc_basepoint;
-               let counterparty_pubkeys = self.counterparty_pubkeys.as_ref().unwrap();
+               let revocation_basepoint = &self.get_holder_pubkeys().revocation_basepoint;
+               let htlc_basepoint = &self.get_holder_pubkeys().htlc_basepoint;
+               let counterparty_pubkeys = self.get_counterparty_pubkeys();
 
                Ok(secp_check!(TxCreationKeys::derive_new(&self.secp_ctx, &self.counterparty_cur_commitment_point.unwrap(), &counterparty_pubkeys.delayed_payment_basepoint, &counterparty_pubkeys.htlc_basepoint, revocation_basepoint, htlc_basepoint), "Remote tx keys generation got bogus keys".to_owned()))
        }
@@ -1171,14 +1165,14 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        /// pays to get_funding_redeemscript().to_v0_p2wsh()).
        /// Panics if called before accept_channel/new_from_req
        pub fn get_funding_redeemscript(&self) -> Script {
-               make_funding_redeemscript(&self.holder_keys.pubkeys().funding_pubkey, self.counterparty_funding_pubkey())
+               make_funding_redeemscript(&self.get_holder_pubkeys().funding_pubkey, self.counterparty_funding_pubkey())
        }
 
        /// Builds the htlc-success or htlc-timeout transaction which spends a given HTLC output
        /// @local is used only to convert relevant internal structures which refer to remote vs local
        /// to decide value of outputs and direction of HTLCs.
        fn build_htlc_transaction(&self, prev_hash: &Txid, htlc: &HTLCOutputInCommitment, local: bool, keys: &TxCreationKeys, feerate_per_kw: u32) -> Transaction {
-               chan_utils::build_htlc_transaction(prev_hash, feerate_per_kw, if local { self.counterparty_selected_contest_delay } else { self.holder_selected_contest_delay }, htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key)
+               chan_utils::build_htlc_transaction(prev_hash, feerate_per_kw, if local { self.get_counterparty_selected_contest_delay() } else { self.get_holder_selected_contest_delay() }, htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key)
        }
 
        /// Per HTLC, only one get_update_fail_htlc or get_update_fulfill_htlc call may be made.
@@ -1388,7 +1382,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
        pub fn accept_channel(&mut self, msg: &msgs::AcceptChannel, config: &UserConfig, their_features: InitFeatures) -> Result<(), ChannelError> {
                // Check sanity of message fields:
-               if !self.channel_outbound {
+               if !self.is_outbound() {
                        return Err(ChannelError::Close("Got an accept_channel message from an inbound peer".to_owned()));
                }
                if self.channel_state != ChannelState::OurInitSent as u32 {
@@ -1406,7 +1400,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                if msg.channel_reserve_satoshis < self.holder_dust_limit_satoshis {
                        return Err(ChannelError::Close(format!("Peer never wants payout outputs? channel_reserve_satoshis was ({}). dust_limit is ({})", msg.channel_reserve_satoshis, self.holder_dust_limit_satoshis)));
                }
-               let remote_reserve = Channel::<ChanSigner>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis);
+               let remote_reserve = Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis);
                if msg.dust_limit_satoshis > remote_reserve {
                        return Err(ChannelError::Close(format!("Dust limit ({}) is bigger than our channel reserve ({})", msg.dust_limit_satoshis, remote_reserve)));
                }
@@ -1421,8 +1415,8 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                if msg.max_accepted_htlcs < 1 {
                        return Err(ChannelError::Close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
                }
-               if msg.max_accepted_htlcs > 483 {
-                       return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than 483", msg.max_accepted_htlcs)));
+               if msg.max_accepted_htlcs > MAX_HTLCS {
+                       return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than {}", msg.max_accepted_htlcs, MAX_HTLCS)));
                }
 
                // Now check against optional parameters as set by config...
@@ -1451,15 +1445,14 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
                        match &msg.shutdown_scriptpubkey {
                                &OptionalField::Present(ref script) => {
-                                       // Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. We enforce it while receiving shutdown msg
-                                       if script.is_p2pkh() || script.is_p2sh() || script.is_v0_p2wsh() || script.is_v0_p2wpkh() {
-                                               Some(script.clone())
                                        // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
-                                       } else if script.len() == 0 {
+                                       if script.len() == 0 {
                                                None
                                        // Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. Fail the channel
+                                       } else if is_unsupported_shutdown_script(&their_features, script) {
+                                               return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided a non-accepted scriptpubkey format. script: ({})", script.to_bytes().to_hex())));
                                        } else {
-                                               return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided a non-accepted scriptpubkey format. scriptpubkey: ({})", script.to_bytes().to_hex())));
+                                               Some(script.clone())
                                        }
                                },
                                // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
@@ -1473,7 +1466,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                self.counterparty_max_htlc_value_in_flight_msat = cmp::min(msg.max_htlc_value_in_flight_msat, self.channel_value_satoshis * 1000);
                self.counterparty_selected_channel_reserve_satoshis = msg.channel_reserve_satoshis;
                self.counterparty_htlc_minimum_msat = msg.htlc_minimum_msat;
-               self.counterparty_selected_contest_delay = msg.to_self_delay;
                self.counterparty_max_accepted_htlcs = msg.max_accepted_htlcs;
                self.minimum_depth = msg.minimum_depth;
 
@@ -1485,8 +1477,10 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        htlc_basepoint: msg.htlc_basepoint
                };
 
-               self.holder_keys.on_accept(&counterparty_pubkeys, msg.to_self_delay, self.holder_selected_contest_delay);
-               self.counterparty_pubkeys = Some(counterparty_pubkeys);
+               self.channel_transaction_parameters.counterparty_parameters = Some(CounterpartyChannelTransactionParameters {
+                       selected_contest_delay: msg.to_self_delay,
+                       pubkeys: counterparty_pubkeys,
+               });
 
                self.counterparty_cur_commitment_point = Some(msg.first_per_commitment_point);
                self.counterparty_shutdown_scriptpubkey = counterparty_shutdown_scriptpubkey;
@@ -1496,35 +1490,40 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                Ok(())
        }
 
-       fn funding_created_signature<L: Deref>(&mut self, sig: &Signature, logger: &L) -> Result<(Transaction, HolderCommitmentTransaction, Signature), ChannelError> where L::Target: Logger {
+       fn funding_created_signature<L: Deref>(&mut self, sig: &Signature, logger: &L) -> Result<(Txid, CommitmentTransaction, Signature), ChannelError> where L::Target: Logger {
                let funding_script = self.get_funding_redeemscript();
 
                let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number)?;
                let initial_commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, false, self.feerate_per_kw, logger).0;
-               let sighash = hash_to_message!(&bip143::SigHashCache::new(&initial_commitment_tx).signature_hash(0, &funding_script, self.channel_value_satoshis, SigHashType::All)[..]);
-
-               // They sign the "our" commitment transaction...
-               log_trace!(logger, "Checking funding_created tx signature {} by key {} against tx {} (sighash {}) with redeemscript {}", log_bytes!(sig.serialize_compact()[..]), log_bytes!(self.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&initial_commitment_tx), log_bytes!(sighash[..]), encode::serialize_hex(&funding_script));
-               secp_check!(self.secp_ctx.verify(&sighash, &sig, self.counterparty_funding_pubkey()), "Invalid funding_created signature from peer".to_owned());
-
-               let tx = HolderCommitmentTransaction::new_missing_holder_sig(initial_commitment_tx, sig.clone(), &self.holder_keys.pubkeys().funding_pubkey, self.counterparty_funding_pubkey(), keys, self.feerate_per_kw, Vec::new());
+               {
+                       let trusted_tx = initial_commitment_tx.trust();
+                       let initial_commitment_bitcoin_tx = trusted_tx.built_transaction();
+                       let sighash = initial_commitment_bitcoin_tx.get_sighash_all(&funding_script, self.channel_value_satoshis);
+                       // They sign the holder commitment transaction...
+                       log_trace!(logger, "Checking funding_created tx signature {} by key {} against tx {} (sighash {}) with redeemscript {}", log_bytes!(sig.serialize_compact()[..]), log_bytes!(self.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&initial_commitment_bitcoin_tx.transaction), log_bytes!(sighash[..]), encode::serialize_hex(&funding_script));
+                       secp_check!(self.secp_ctx.verify(&sighash, &sig, self.counterparty_funding_pubkey()), "Invalid funding_created signature from peer".to_owned());
+               }
 
                let counterparty_keys = self.build_remote_transaction_keys()?;
                let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, self.feerate_per_kw, logger).0;
-               let pre_remote_keys = PreCalculatedTxCreationKeys::new(counterparty_keys);
-               let counterparty_signature = self.holder_keys.sign_counterparty_commitment(self.feerate_per_kw, &counterparty_initial_commitment_tx, &pre_remote_keys, &Vec::new(), &self.secp_ctx)
+
+               let counterparty_trusted_tx = counterparty_initial_commitment_tx.trust();
+               let counterparty_initial_bitcoin_tx = counterparty_trusted_tx.built_transaction();
+               log_trace!(logger, "Initial counterparty ID {} tx {}", counterparty_initial_bitcoin_tx.txid, encode::serialize_hex(&counterparty_initial_bitcoin_tx.transaction));
+
+               let counterparty_signature = self.holder_signer.sign_counterparty_commitment(&counterparty_initial_commitment_tx, &self.secp_ctx)
                                .map_err(|_| ChannelError::Close("Failed to get signatures for new commitment_signed".to_owned()))?.0;
 
                // We sign "counterparty" commitment transaction, allowing them to broadcast the tx if they wish.
-               Ok((counterparty_initial_commitment_tx, tx, counterparty_signature))
+               Ok((counterparty_initial_bitcoin_tx.txid, initial_commitment_tx, counterparty_signature))
        }
 
        fn counterparty_funding_pubkey(&self) -> &PublicKey {
-               &self.counterparty_pubkeys.as_ref().expect("funding_pubkey() only allowed after accept_channel").funding_pubkey
+               &self.get_counterparty_pubkeys().funding_pubkey
        }
 
-       pub fn funding_created<L: Deref>(&mut self, msg: &msgs::FundingCreated, logger: &L) -> Result<(msgs::FundingSigned, ChannelMonitor<ChanSigner>), ChannelError> where L::Target: Logger {
-               if self.channel_outbound {
+       pub fn funding_created<L: Deref>(&mut self, msg: &msgs::FundingCreated, logger: &L) -> Result<(msgs::FundingSigned, ChannelMonitor<Signer>), ChannelError> where L::Target: Logger {
+               if self.is_outbound() {
                        return Err(ChannelError::Close("Received funding_created for an outbound channel?".to_owned()));
                }
                if self.channel_state != (ChannelState::OurInitSent as u32 | ChannelState::TheirInitSent as u32) {
@@ -1539,38 +1538,47 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        panic!("Should not have advanced channel commitment tx numbers prior to funding_created");
                }
 
-               let funding_txo = OutPoint{ txid: msg.funding_txid, index: msg.funding_output_index };
-               self.funding_txo = Some(funding_txo.clone());
+               let funding_txo = OutPoint { txid: msg.funding_txid, index: msg.funding_output_index };
+               self.channel_transaction_parameters.funding_outpoint = Some(funding_txo);
+               // This is an externally observable change before we finish all our checks.  In particular
+               // funding_created_signature may fail.
+               self.holder_signer.ready_channel(&self.channel_transaction_parameters);
 
-               let (counterparty_initial_commitment_tx, initial_commitment_tx, signature) = match self.funding_created_signature(&msg.signature, logger) {
+               let (counterparty_initial_commitment_txid, initial_commitment_tx, signature) = match self.funding_created_signature(&msg.signature, logger) {
                        Ok(res) => res,
+                       Err(ChannelError::Close(e)) => {
+                               self.channel_transaction_parameters.funding_outpoint = None;
+                               return Err(ChannelError::Close(e));
+                       },
                        Err(e) => {
-                               self.funding_txo = None;
-                               return Err(e);
+                               // The only error we know how to handle is ChannelError::Close, so we fall over here
+                               // to make sure we don't continue with an inconsistent state.
+                               panic!("unexpected error type from funding_created_signature {:?}", e);
                        }
                };
 
+               let holder_commitment_tx = HolderCommitmentTransaction::new(
+                       initial_commitment_tx,
+                       msg.signature,
+                       Vec::new(),
+                       &self.get_holder_pubkeys().funding_pubkey,
+                       self.counterparty_funding_pubkey()
+               );
+
                // Now that we're past error-generating stuff, update our local state:
 
-               let counterparty_pubkeys = self.counterparty_pubkeys.as_ref().unwrap();
                let funding_redeemscript = self.get_funding_redeemscript();
                let funding_txo_script = funding_redeemscript.to_v0_p2wsh();
-               macro_rules! create_monitor {
-                       () => { {
-                               let mut channel_monitor = ChannelMonitor::new(self.holder_keys.clone(),
-                                                                             &self.shutdown_pubkey, self.holder_selected_contest_delay,
-                                                                             &self.destination_script, (funding_txo, funding_txo_script.clone()),
-                                                                             &counterparty_pubkeys.htlc_basepoint, &counterparty_pubkeys.delayed_payment_basepoint,
-                                                                             self.counterparty_selected_contest_delay, funding_redeemscript.clone(), self.channel_value_satoshis,
-                                                                             self.get_commitment_transaction_number_obscure_factor(),
-                                                                             initial_commitment_tx.clone());
-
-                               channel_monitor.provide_latest_counterparty_commitment_tx_info(&counterparty_initial_commitment_tx, Vec::new(), self.cur_counterparty_commitment_transaction_number, self.counterparty_cur_commitment_point.unwrap(), logger);
-                               channel_monitor
-                       } }
-               }
+               let obscure_factor = get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound());
+               let channel_monitor = ChannelMonitor::new(self.secp_ctx.clone(), self.holder_signer.clone(),
+                                                         &self.shutdown_pubkey, self.get_holder_selected_contest_delay(),
+                                                         &self.destination_script, (funding_txo, funding_txo_script.clone()),
+                                                         &self.channel_transaction_parameters,
+                                                         funding_redeemscript.clone(), self.channel_value_satoshis,
+                                                         obscure_factor,
+                                                         holder_commitment_tx);
 
-               let channel_monitor = create_monitor!();
+               channel_monitor.provide_latest_counterparty_commitment_tx(counterparty_initial_commitment_txid, Vec::new(), self.cur_counterparty_commitment_transaction_number, self.counterparty_cur_commitment_point.unwrap(), logger);
 
                self.channel_state = ChannelState::FundingSent as u32;
                self.channel_id = funding_txo.to_channel_id();
@@ -1585,8 +1593,8 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
        /// Handles a funding_signed message from the remote end.
        /// If this call is successful, broadcast the funding transaction (and not before!)
-       pub fn funding_signed<L: Deref>(&mut self, msg: &msgs::FundingSigned, logger: &L) -> Result<ChannelMonitor<ChanSigner>, ChannelError> where L::Target: Logger {
-               if !self.channel_outbound {
+       pub fn funding_signed<L: Deref>(&mut self, msg: &msgs::FundingSigned, logger: &L) -> Result<ChannelMonitor<Signer>, ChannelError> where L::Target: Logger {
+               if !self.is_outbound() {
                        return Err(ChannelError::Close("Received funding_signed for an inbound channel?".to_owned()));
                }
                if self.channel_state & !(ChannelState::MonitorUpdateFailed as u32) != ChannelState::FundingCreated as u32 {
@@ -1602,40 +1610,45 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
                let counterparty_keys = self.build_remote_transaction_keys()?;
                let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, self.feerate_per_kw, logger).0;
+               let counterparty_trusted_tx = counterparty_initial_commitment_tx.trust();
+               let counterparty_initial_bitcoin_tx = counterparty_trusted_tx.built_transaction();
 
-               let holder_keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number)?;
-               let initial_commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &holder_keys, true, false, self.feerate_per_kw, logger).0;
-               let sighash = hash_to_message!(&bip143::SigHashCache::new(&initial_commitment_tx).signature_hash(0, &funding_script, self.channel_value_satoshis, SigHashType::All)[..]);
-
-               let counterparty_funding_pubkey = &self.counterparty_pubkeys.as_ref().unwrap().funding_pubkey;
+               log_trace!(logger, "Initial counterparty ID {} tx {}", counterparty_initial_bitcoin_tx.txid, encode::serialize_hex(&counterparty_initial_bitcoin_tx.transaction));
 
-               // They sign our commitment transaction, allowing us to broadcast the tx if we wish.
-               if let Err(_) = self.secp_ctx.verify(&sighash, &msg.signature, counterparty_funding_pubkey) {
-                       return Err(ChannelError::Close("Invalid funding_signed signature from peer".to_owned()));
+               let holder_signer = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number)?;
+               let initial_commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &holder_signer, true, false, self.feerate_per_kw, logger).0;
+               {
+                       let trusted_tx = initial_commitment_tx.trust();
+                       let initial_commitment_bitcoin_tx = trusted_tx.built_transaction();
+                       let sighash = initial_commitment_bitcoin_tx.get_sighash_all(&funding_script, self.channel_value_satoshis);
+                       // They sign our commitment transaction, allowing us to broadcast the tx if we wish.
+                       if let Err(_) = self.secp_ctx.verify(&sighash, &msg.signature, &self.get_counterparty_pubkeys().funding_pubkey) {
+                               return Err(ChannelError::Close("Invalid funding_signed signature from peer".to_owned()));
+                       }
                }
 
-               let counterparty_pubkeys = self.counterparty_pubkeys.as_ref().unwrap();
+               let holder_commitment_tx = HolderCommitmentTransaction::new(
+                       initial_commitment_tx,
+                       msg.signature,
+                       Vec::new(),
+                       &self.get_holder_pubkeys().funding_pubkey,
+                       self.counterparty_funding_pubkey()
+               );
+
+
                let funding_redeemscript = self.get_funding_redeemscript();
-               let funding_txo = self.funding_txo.as_ref().unwrap();
+               let funding_txo = self.get_funding_txo().unwrap();
                let funding_txo_script = funding_redeemscript.to_v0_p2wsh();
-               macro_rules! create_monitor {
-                       () => { {
-                               let commitment_tx = HolderCommitmentTransaction::new_missing_holder_sig(initial_commitment_tx.clone(), msg.signature.clone(), &self.holder_keys.pubkeys().funding_pubkey, counterparty_funding_pubkey, holder_keys.clone(), self.feerate_per_kw, Vec::new());
-                               let mut channel_monitor = ChannelMonitor::new(self.holder_keys.clone(),
-                                                                             &self.shutdown_pubkey, self.holder_selected_contest_delay,
-                                                                             &self.destination_script, (funding_txo.clone(), funding_txo_script.clone()),
-                                                                             &counterparty_pubkeys.htlc_basepoint, &counterparty_pubkeys.delayed_payment_basepoint,
-                                                                             self.counterparty_selected_contest_delay, funding_redeemscript.clone(), self.channel_value_satoshis,
-                                                                             self.get_commitment_transaction_number_obscure_factor(),
-                                                                             commitment_tx);
-
-                               channel_monitor.provide_latest_counterparty_commitment_tx_info(&counterparty_initial_commitment_tx, Vec::new(), self.cur_counterparty_commitment_transaction_number, self.counterparty_cur_commitment_point.unwrap(), logger);
-
-                               channel_monitor
-                       } }
-               }
+               let obscure_factor = get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound());
+               let channel_monitor = ChannelMonitor::new(self.secp_ctx.clone(), self.holder_signer.clone(),
+                                                         &self.shutdown_pubkey, self.get_holder_selected_contest_delay(),
+                                                         &self.destination_script, (funding_txo, funding_txo_script),
+                                                         &self.channel_transaction_parameters,
+                                                         funding_redeemscript.clone(), self.channel_value_satoshis,
+                                                         obscure_factor,
+                                                         holder_commitment_tx);
 
-               let channel_monitor = create_monitor!();
+               channel_monitor.provide_latest_counterparty_commitment_tx(counterparty_initial_bitcoin_tx.txid, Vec::new(), self.cur_counterparty_commitment_transaction_number, self.counterparty_cur_commitment_point.unwrap(), logger);
 
                assert_eq!(self.channel_state & (ChannelState::MonitorUpdateFailed as u32), 0); // We have no had any monitor(s) yet to fail update!
                self.channel_state = ChannelState::FundingSent as u32;
@@ -1724,63 +1737,172 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                (COMMITMENT_TX_BASE_WEIGHT + num_htlcs as u64 * COMMITMENT_TX_WEIGHT_PER_HTLC) * self.feerate_per_kw as u64 / 1000 * 1000
        }
 
-       // Get the commitment tx fee for the local (i.e our) next commitment transaction
-       // based on the number of pending HTLCs that are on track to be in our next
-       // commitment tx. `addl_htcs` is an optional parameter allowing the caller
-       // to add a number of additional HTLCs to the calculation. Note that dust
-       // HTLCs are excluded.
-       fn next_local_commit_tx_fee_msat(&self, addl_htlcs: usize) -> u64 {
-               assert!(self.channel_outbound);
+       // Get the commitment tx fee for the local's (i.e. our) next commitment transaction based on the
+       // number of pending HTLCs that are on track to be in our next commitment tx, plus an additional
+       // HTLC if `fee_spike_buffer_htlc` is Some, plus a new HTLC given by `new_htlc_amount`. Dust HTLCs
+       // are excluded.
+       fn next_local_commit_tx_fee_msat(&self, htlc: HTLCCandidate, fee_spike_buffer_htlc: Option<()>) -> u64 {
+               assert!(self.is_outbound());
+
+               let real_dust_limit_success_sat = (self.feerate_per_kw as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis;
+               let real_dust_limit_timeout_sat = (self.feerate_per_kw as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis;
+
+               let mut addl_htlcs = 0;
+               if fee_spike_buffer_htlc.is_some() { addl_htlcs += 1; }
+               match htlc.origin {
+                       HTLCInitiator::LocalOffered => {
+                               if htlc.amount_msat / 1000 >= real_dust_limit_timeout_sat {
+                                       addl_htlcs += 1;
+                               }
+                       },
+                       HTLCInitiator::RemoteOffered => {
+                               if htlc.amount_msat / 1000 >= real_dust_limit_success_sat {
+                                       addl_htlcs += 1;
+                               }
+                       }
+               }
+
+               let mut included_htlcs = 0;
+               for ref htlc in self.pending_inbound_htlcs.iter() {
+                       if htlc.amount_msat / 1000 < real_dust_limit_success_sat {
+                               continue
+                       }
+                       // We include LocalRemoved HTLCs here because we may still need to broadcast a commitment
+                       // transaction including this HTLC if it times out before they RAA.
+                       included_htlcs += 1;
+               }
 
-               let mut their_acked_htlcs = self.pending_inbound_htlcs.len();
                for ref htlc in self.pending_outbound_htlcs.iter() {
-                       if htlc.amount_msat / 1000 <= self.holder_dust_limit_satoshis {
+                       if htlc.amount_msat / 1000 < real_dust_limit_timeout_sat {
                                continue
                        }
                        match htlc.state {
-                               OutboundHTLCState::Committed => their_acked_htlcs += 1,
-                               OutboundHTLCState::RemoteRemoved {..} => their_acked_htlcs += 1,
-                               OutboundHTLCState::LocalAnnounced {..} => their_acked_htlcs += 1,
+                               OutboundHTLCState::LocalAnnounced {..} => included_htlcs += 1,
+                               OutboundHTLCState::Committed => included_htlcs += 1,
+                               OutboundHTLCState::RemoteRemoved {..} => included_htlcs += 1,
+                               // We don't include AwaitingRemoteRevokeToRemove HTLCs because our next commitment
+                               // transaction won't be generated until they send us their next RAA, which will mean
+                               // dropping any HTLCs in this state.
                                _ => {},
                        }
                }
 
                for htlc in self.holding_cell_htlc_updates.iter() {
                        match htlc {
-                               &HTLCUpdateAwaitingACK::AddHTLC { .. } => their_acked_htlcs += 1,
-                               _ => {},
+                               &HTLCUpdateAwaitingACK::AddHTLC { amount_msat, .. } => {
+                                       if amount_msat / 1000 < real_dust_limit_timeout_sat {
+                                               continue
+                                       }
+                                       included_htlcs += 1
+                               },
+                               _ => {}, // Don't include claims/fails that are awaiting ack, because once we get the
+                                        // ack we're guaranteed to never include them in commitment txs anymore.
                        }
                }
 
-               self.commit_tx_fee_msat(their_acked_htlcs + addl_htlcs)
+               let num_htlcs = included_htlcs + addl_htlcs;
+               let res = self.commit_tx_fee_msat(num_htlcs);
+               #[cfg(any(test, feature = "fuzztarget"))]
+               {
+                       let mut fee = res;
+                       if fee_spike_buffer_htlc.is_some() {
+                               fee = self.commit_tx_fee_msat(num_htlcs - 1);
+                       }
+                       let total_pending_htlcs = self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len()
+                               + self.holding_cell_htlc_updates.len();
+                       let commitment_tx_info = CommitmentTxInfoCached {
+                               fee,
+                               total_pending_htlcs,
+                               next_holder_htlc_id: match htlc.origin {
+                                       HTLCInitiator::LocalOffered => self.next_holder_htlc_id + 1,
+                                       HTLCInitiator::RemoteOffered => self.next_holder_htlc_id,
+                               },
+                               next_counterparty_htlc_id: match htlc.origin {
+                                       HTLCInitiator::LocalOffered => self.next_counterparty_htlc_id,
+                                       HTLCInitiator::RemoteOffered => self.next_counterparty_htlc_id + 1,
+                               },
+                               feerate: self.feerate_per_kw,
+                       };
+                       *self.next_local_commitment_tx_fee_info_cached.lock().unwrap() = Some(commitment_tx_info);
+               }
+               res
        }
 
-       // Get the commitment tx fee for the remote's next commitment transaction
-       // based on the number of pending HTLCs that are on track to be in their
-       // next commitment tx. `addl_htcs` is an optional parameter allowing the caller
-       // to add a number of additional HTLCs to the calculation. Note that dust HTLCs
-       // are excluded.
-       fn next_remote_commit_tx_fee_msat(&self, addl_htlcs: usize) -> u64 {
-               assert!(!self.channel_outbound);
+       // Get the commitment tx fee for the remote's next commitment transaction based on the number of
+       // pending HTLCs that are on track to be in their next commitment tx, plus an additional HTLC if
+       // `fee_spike_buffer_htlc` is Some, plus a new HTLC given by `new_htlc_amount`. Dust HTLCs are
+       // excluded.
+       fn next_remote_commit_tx_fee_msat(&self, htlc: HTLCCandidate, fee_spike_buffer_htlc: Option<()>) -> u64 {
+               assert!(!self.is_outbound());
+
+               let real_dust_limit_success_sat = (self.feerate_per_kw as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis;
+               let real_dust_limit_timeout_sat = (self.feerate_per_kw as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis;
+
+               let mut addl_htlcs = 0;
+               if fee_spike_buffer_htlc.is_some() { addl_htlcs += 1; }
+               match htlc.origin {
+                       HTLCInitiator::LocalOffered => {
+                               if htlc.amount_msat / 1000 >= real_dust_limit_success_sat {
+                                       addl_htlcs += 1;
+                               }
+                       },
+                       HTLCInitiator::RemoteOffered => {
+                               if htlc.amount_msat / 1000 >= real_dust_limit_timeout_sat {
+                                       addl_htlcs += 1;
+                               }
+                       }
+               }
+
+               // When calculating the set of HTLCs which will be included in their next commitment_signed, all
+               // non-dust inbound HTLCs are included (as all states imply it will be included) and only
+               // committed outbound HTLCs, see below.
+               let mut included_htlcs = 0;
+               for ref htlc in self.pending_inbound_htlcs.iter() {
+                       if htlc.amount_msat / 1000 <= real_dust_limit_timeout_sat {
+                               continue
+                       }
+                       included_htlcs += 1;
+               }
 
-               // When calculating the set of HTLCs which will be included in their next
-               // commitment_signed, all inbound HTLCs are included (as all states imply it will be
-               // included) and only committed outbound HTLCs, see below.
-               let mut their_acked_htlcs = self.pending_inbound_htlcs.len();
                for ref htlc in self.pending_outbound_htlcs.iter() {
-                       if htlc.amount_msat / 1000 <= self.counterparty_dust_limit_satoshis {
+                       if htlc.amount_msat / 1000 <= real_dust_limit_success_sat {
                                continue
                        }
-                       // We only include outbound HTLCs if it will not be included in their next
-                       // commitment_signed, i.e. if they've responded to us with an RAA after announcement.
+                       // We only include outbound HTLCs if it will not be included in their next commitment_signed,
+                       // i.e. if they've responded to us with an RAA after announcement.
                        match htlc.state {
-                               OutboundHTLCState::Committed => their_acked_htlcs += 1,
-                               OutboundHTLCState::RemoteRemoved {..} => their_acked_htlcs += 1,
+                               OutboundHTLCState::Committed => included_htlcs += 1,
+                               OutboundHTLCState::RemoteRemoved {..} => included_htlcs += 1,
+                               OutboundHTLCState::LocalAnnounced { .. } => included_htlcs += 1,
                                _ => {},
                        }
                }
 
-               self.commit_tx_fee_msat(their_acked_htlcs + addl_htlcs)
+               let num_htlcs = included_htlcs + addl_htlcs;
+               let res = self.commit_tx_fee_msat(num_htlcs);
+               #[cfg(any(test, feature = "fuzztarget"))]
+               {
+                       let mut fee = res;
+                       if fee_spike_buffer_htlc.is_some() {
+                               fee = self.commit_tx_fee_msat(num_htlcs - 1);
+                       }
+                       let total_pending_htlcs = self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len();
+                       let commitment_tx_info = CommitmentTxInfoCached {
+                               fee,
+                               total_pending_htlcs,
+                               next_holder_htlc_id: match htlc.origin {
+                                       HTLCInitiator::LocalOffered => self.next_holder_htlc_id + 1,
+                                       HTLCInitiator::RemoteOffered => self.next_holder_htlc_id,
+                               },
+                               next_counterparty_htlc_id: match htlc.origin {
+                                       HTLCInitiator::LocalOffered => self.next_counterparty_htlc_id,
+                                       HTLCInitiator::RemoteOffered => self.next_counterparty_htlc_id + 1,
+                               },
+                               feerate: self.feerate_per_kw,
+                       };
+                       *self.next_remote_commitment_tx_fee_info_cached.lock().unwrap() = Some(commitment_tx_info);
+               }
+               res
        }
 
        pub fn update_add_htlc<F, L: Deref>(&mut self, msg: &msgs::UpdateAddHTLC, mut pending_forward_status: PendingHTLCStatus, create_pending_htlc_status: F, logger: &L) -> Result<(), ChannelError>
@@ -1812,7 +1934,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                if inbound_htlc_count + 1 > OUR_MAX_HTLCS as u32 {
                        return Err(ChannelError::Close(format!("Remote tried to push more than our max accepted HTLCs ({})", OUR_MAX_HTLCS)));
                }
-               let holder_max_htlc_value_in_flight_msat = Channel::<ChanSigner>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis);
+               let holder_max_htlc_value_in_flight_msat = Channel::<Signer>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis);
                if htlc_inbound_value_msat + msg.amount_msat > holder_max_htlc_value_in_flight_msat {
                        return Err(ChannelError::Close(format!("Remote HTLC add would put them over our max HTLC value ({})", holder_max_htlc_value_in_flight_msat)));
                }
@@ -1847,29 +1969,31 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
                // Check that the remote can afford to pay for this HTLC on-chain at the current
                // feerate_per_kw, while maintaining their channel reserve (as required by the spec).
-               let remote_commit_tx_fee_msat = if self.channel_outbound { 0 } else {
-                       // +1 for this HTLC.
-                       self.next_remote_commit_tx_fee_msat(1)
+               let remote_commit_tx_fee_msat = if self.is_outbound() { 0 } else {
+                       let htlc_candidate = HTLCCandidate::new(msg.amount_msat, HTLCInitiator::RemoteOffered);
+                       self.next_remote_commit_tx_fee_msat(htlc_candidate, None) // Don't include the extra fee spike buffer HTLC in calculations
                };
                if pending_remote_value_msat - msg.amount_msat < remote_commit_tx_fee_msat {
                        return Err(ChannelError::Close("Remote HTLC add would not leave enough to pay for fees".to_owned()));
                };
 
                let chan_reserve_msat =
-                       Channel::<ChanSigner>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis) * 1000;
+                       Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis) * 1000;
                if pending_remote_value_msat - msg.amount_msat - remote_commit_tx_fee_msat < chan_reserve_msat {
                        return Err(ChannelError::Close("Remote HTLC add would put them under remote reserve value".to_owned()));
                }
 
-               if !self.channel_outbound {
-                       // `+1` for this HTLC, `2 *` and `+1` fee spike buffer we keep for the remote. This deviates from the
-                       // spec because in the spec, the fee spike buffer requirement doesn't exist on the receiver's side,
-                       // only on the sender's.
-                       // Note that when we eventually remove support for fee updates and switch to anchor output fees,
-                       // we will drop the `2 *`, since we no longer be as sensitive to fee spikes. But, keep the extra +1
-                       // as we should still be able to afford adding this HTLC plus one more future HTLC, regardless of
-                       // being sensitive to fee spikes.
-                       let remote_fee_cost_incl_stuck_buffer_msat = 2 * self.next_remote_commit_tx_fee_msat(1 + 1);
+               if !self.is_outbound() {
+                       // `2 *` and `Some(())` is for the fee spike buffer we keep for the remote. This deviates from
+                       // the spec because in the spec, the fee spike buffer requirement doesn't exist on the
+                       // receiver's side, only on the sender's.
+                       // Note that when we eventually remove support for fee updates and switch to anchor output
+                       // fees, we will drop the `2 *`, since we no longer be as sensitive to fee spikes. But, keep
+                       // the extra htlc when calculating the next remote commitment transaction fee as we should
+                       // still be able to afford adding this HTLC plus one more future HTLC, regardless of being
+                       // sensitive to fee spikes.
+                       let htlc_candidate = HTLCCandidate::new(msg.amount_msat, HTLCInitiator::RemoteOffered);
+                       let remote_fee_cost_incl_stuck_buffer_msat = 2 * self.next_remote_commit_tx_fee_msat(htlc_candidate, Some(()));
                        if pending_remote_value_msat - msg.amount_msat - chan_reserve_msat < remote_fee_cost_incl_stuck_buffer_msat {
                                // Note that if the pending_forward_status is not updated here, then it's because we're already failing
                                // the HTLC, i.e. its status is already set to failing.
@@ -1878,9 +2002,8 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        }
                } else {
                        // Check that they won't violate our local required channel reserve by adding this HTLC.
-
-                       // +1 for this HTLC.
-                       let local_commit_tx_fee_msat = self.next_local_commit_tx_fee_msat(1);
+                       let htlc_candidate = HTLCCandidate::new(msg.amount_msat, HTLCInitiator::RemoteOffered);
+                       let local_commit_tx_fee_msat = self.next_local_commit_tx_fee_msat(htlc_candidate, None);
                        if self.value_to_self_msat < self.counterparty_selected_channel_reserve_satoshis * 1000 + local_commit_tx_fee_msat {
                                return Err(ChannelError::Close("Cannot accept HTLC that would put our balance under counterparty-announced channel reserve value".to_owned()));
                        }
@@ -1992,45 +2115,63 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number).map_err(|e| (None, e))?;
 
                let mut update_fee = false;
-               let feerate_per_kw = if !self.channel_outbound && self.pending_update_fee.is_some() {
+               let feerate_per_kw = if !self.is_outbound() && self.pending_update_fee.is_some() {
                        update_fee = true;
                        self.pending_update_fee.unwrap()
                } else {
                        self.feerate_per_kw
                };
 
-               let mut commitment_tx = {
-                       let mut commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, false, feerate_per_kw, logger);
-                       let htlcs_cloned: Vec<_> = commitment_tx.2.drain(..).map(|htlc| (htlc.0, htlc.1.map(|h| h.clone()))).collect();
-                       (commitment_tx.0, commitment_tx.1, htlcs_cloned)
+               let (num_htlcs, mut htlcs_cloned, commitment_tx, commitment_txid) = {
+                       let commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, false, feerate_per_kw, logger);
+                       let commitment_txid = {
+                               let trusted_tx = commitment_tx.0.trust();
+                               let bitcoin_tx = trusted_tx.built_transaction();
+                               let sighash = bitcoin_tx.get_sighash_all(&funding_script, self.channel_value_satoshis);
+
+                               log_trace!(logger, "Checking commitment tx signature {} by key {} against tx {} (sighash {}) with redeemscript {}", log_bytes!(msg.signature.serialize_compact()[..]), log_bytes!(self.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&bitcoin_tx.transaction), log_bytes!(sighash[..]), encode::serialize_hex(&funding_script));
+                               if let Err(_) = self.secp_ctx.verify(&sighash, &msg.signature, &self.counterparty_funding_pubkey()) {
+                                       return Err((None, ChannelError::Close("Invalid commitment tx signature from peer".to_owned())));
+                               }
+                               bitcoin_tx.txid
+                       };
+                       let htlcs_cloned: Vec<_> = commitment_tx.2.iter().map(|htlc| (htlc.0.clone(), htlc.1.map(|h| h.clone()))).collect();
+                       (commitment_tx.1, htlcs_cloned, commitment_tx.0, commitment_txid)
                };
-               let commitment_txid = commitment_tx.0.txid();
-               let sighash = hash_to_message!(&bip143::SigHashCache::new(&commitment_tx.0).signature_hash(0, &funding_script, self.channel_value_satoshis, SigHashType::All)[..]);
-               log_trace!(logger, "Checking commitment tx signature {} by key {} against tx {} (sighash {}) with redeemscript {}", log_bytes!(msg.signature.serialize_compact()[..]), log_bytes!(self.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&commitment_tx.0), log_bytes!(sighash[..]), encode::serialize_hex(&funding_script));
-               if let Err(_) = self.secp_ctx.verify(&sighash, &msg.signature, &self.counterparty_funding_pubkey()) {
-                       return Err((None, ChannelError::Close("Invalid commitment tx signature from peer".to_owned())));
-               }
 
+               let total_fee = feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + (num_htlcs as u64) * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000;
                //If channel fee was updated by funder confirm funder can afford the new fee rate when applied to the current local commitment transaction
                if update_fee {
-                       let num_htlcs = commitment_tx.1;
-                       let total_fee = feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + (num_htlcs as u64) * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000;
-
-                       let counterparty_reserve_we_require = Channel::<ChanSigner>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis);
+                       let counterparty_reserve_we_require = Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis);
                        if self.channel_value_satoshis - self.value_to_self_msat / 1000 < total_fee + counterparty_reserve_we_require {
                                return Err((None, ChannelError::Close("Funding remote cannot afford proposed new fee".to_owned())));
                        }
                }
+               #[cfg(any(test, feature = "fuzztarget"))]
+               {
+                       if self.is_outbound() {
+                               let projected_commit_tx_info = self.next_local_commitment_tx_fee_info_cached.lock().unwrap().take();
+                               *self.next_remote_commitment_tx_fee_info_cached.lock().unwrap() = None;
+                               if let Some(info) = projected_commit_tx_info {
+                                       let total_pending_htlcs = self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len()
+                                               + self.holding_cell_htlc_updates.len();
+                                       if info.total_pending_htlcs == total_pending_htlcs
+                                               && info.next_holder_htlc_id == self.next_holder_htlc_id
+                                               && info.next_counterparty_htlc_id == self.next_counterparty_htlc_id
+                                               && info.feerate == self.feerate_per_kw {
+                                                       assert_eq!(total_fee, info.fee / 1000);
+                                               }
+                               }
+                       }
+               }
 
-               if msg.htlc_signatures.len() != commitment_tx.1 {
-                       return Err((None, ChannelError::Close(format!("Got wrong number of HTLC signatures ({}) from remote. It must be {}", msg.htlc_signatures.len(), commitment_tx.1))));
+               if msg.htlc_signatures.len() != num_htlcs {
+                       return Err((None, ChannelError::Close(format!("Got wrong number of HTLC signatures ({}) from remote. It must be {}", msg.htlc_signatures.len(), num_htlcs))));
                }
 
-               // TODO: Merge these two, sadly they are currently both required to be passed separately to
-               // ChannelMonitor:
-               let mut htlcs_without_source = Vec::with_capacity(commitment_tx.2.len());
-               let mut htlcs_and_sigs = Vec::with_capacity(commitment_tx.2.len());
-               for (idx, (htlc, source)) in commitment_tx.2.drain(..).enumerate() {
+               // TODO: Sadly, we pass HTLCs twice to ChannelMonitor: once via the HolderCommitmentTransaction and once via the update
+               let mut htlcs_and_sigs = Vec::with_capacity(htlcs_cloned.len());
+               for (idx, (htlc, source)) in htlcs_cloned.drain(..).enumerate() {
                        if let Some(_) = htlc.transaction_output_index {
                                let htlc_tx = self.build_htlc_transaction(&commitment_txid, &htlc, true, &keys, feerate_per_kw);
                                let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
@@ -2039,20 +2180,26 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                                if let Err(_) = self.secp_ctx.verify(&htlc_sighash, &msg.htlc_signatures[idx], &keys.countersignatory_htlc_key) {
                                        return Err((None, ChannelError::Close("Invalid HTLC tx signature from peer".to_owned())));
                                }
-                               htlcs_without_source.push((htlc.clone(), Some(msg.htlc_signatures[idx])));
                                htlcs_and_sigs.push((htlc, Some(msg.htlc_signatures[idx]), source));
                        } else {
-                               htlcs_without_source.push((htlc.clone(), None));
                                htlcs_and_sigs.push((htlc, None, source));
                        }
                }
 
-               let next_per_commitment_point = self.holder_keys.get_per_commitment_point(self.cur_holder_commitment_transaction_number - 1, &self.secp_ctx);
-               let per_commitment_secret = self.holder_keys.release_commitment_secret(self.cur_holder_commitment_transaction_number + 1);
+               let holder_commitment_tx = HolderCommitmentTransaction::new(
+                       commitment_tx,
+                       msg.signature,
+                       msg.htlc_signatures.clone(),
+                       &self.get_holder_pubkeys().funding_pubkey,
+                       self.counterparty_funding_pubkey()
+               );
+
+               let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number - 1, &self.secp_ctx);
+               let per_commitment_secret = self.holder_signer.release_commitment_secret(self.cur_holder_commitment_transaction_number + 1);
 
                // Update state now that we've passed all the can-fail calls...
                let mut need_commitment = false;
-               if !self.channel_outbound {
+               if !self.is_outbound() {
                        if let Some(fee_update) = self.pending_update_fee {
                                self.feerate_per_kw = fee_update;
                                // We later use the presence of pending_update_fee to indicate we should generate a
@@ -2065,13 +2212,11 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        }
                }
 
-               let counterparty_funding_pubkey = self.counterparty_pubkeys.as_ref().unwrap().funding_pubkey;
-
                self.latest_monitor_update_id += 1;
                let mut monitor_update = ChannelMonitorUpdate {
                        update_id: self.latest_monitor_update_id,
                        updates: vec![ChannelMonitorUpdateStep::LatestHolderCommitmentTXInfo {
-                               commitment_tx: HolderCommitmentTransaction::new_missing_holder_sig(commitment_tx.0, msg.signature.clone(), &self.holder_keys.pubkeys().funding_pubkey, &counterparty_funding_pubkey, keys, self.feerate_per_kw, htlcs_without_source),
+                               commitment_tx: holder_commitment_tx,
                                htlc_outputs: htlcs_and_sigs
                        }]
                };
@@ -2284,6 +2429,12 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        return Err(ChannelError::Close("Received an unexpected revoke_and_ack".to_owned()));
                }
 
+               #[cfg(any(test, feature = "fuzztarget"))]
+               {
+                       *self.next_local_commitment_tx_fee_info_cached.lock().unwrap() = None;
+                       *self.next_remote_commitment_tx_fee_info_cached.lock().unwrap() = None;
+               }
+
                self.commitment_secrets.provide_secret(self.cur_counterparty_commitment_transaction_number + 1, msg.per_commitment_secret)
                        .map_err(|_| ChannelError::Close("Previous secrets did not match new one".to_owned()))?;
                self.latest_monitor_update_id += 1;
@@ -2393,7 +2544,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                }
                self.value_to_self_msat = (self.value_to_self_msat as i64 + value_to_self_msat_diff) as u64;
 
-               if self.channel_outbound {
+               if self.is_outbound() {
                        if let Some(feerate) = self.pending_update_fee.take() {
                                self.feerate_per_kw = feerate;
                        }
@@ -2477,7 +2628,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        /// further details on the optionness of the return value.
        /// You MUST call send_commitment prior to any other calls on this Channel
        fn send_update_fee(&mut self, feerate_per_kw: u32) -> Option<msgs::UpdateFee> {
-               if !self.channel_outbound {
+               if !self.is_outbound() {
                        panic!("Cannot send fee from inbound channel");
                }
                if !self.is_usable() {
@@ -2609,7 +2760,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                assert_eq!(self.channel_state & ChannelState::MonitorUpdateFailed as u32, ChannelState::MonitorUpdateFailed as u32);
                self.channel_state &= !(ChannelState::MonitorUpdateFailed as u32);
 
-               let needs_broadcast_safe = self.channel_state & (ChannelState::FundingSent as u32) != 0 && self.channel_outbound;
+               let needs_broadcast_safe = self.channel_state & (ChannelState::FundingSent as u32) != 0 && self.is_outbound();
 
                // Because we will never generate a FundingBroadcastSafe event when we're in
                // MonitorUpdateFailed, if we assume the user only broadcast the funding transaction when
@@ -2618,9 +2769,9 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                // monitor on funding_created, and we even got the funding transaction confirmed before the
                // monitor was persisted.
                let funding_locked = if self.monitor_pending_funding_locked {
-                       assert!(!self.channel_outbound, "Funding transaction broadcast without FundingBroadcastSafe!");
+                       assert!(!self.is_outbound(), "Funding transaction broadcast without FundingBroadcastSafe!");
                        self.monitor_pending_funding_locked = false;
-                       let next_per_commitment_point = self.holder_keys.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
+                       let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
                        Some(msgs::FundingLocked {
                                channel_id: self.channel_id(),
                                next_per_commitment_point,
@@ -2659,21 +2810,21 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        pub fn update_fee<F: Deref>(&mut self, fee_estimator: &F, msg: &msgs::UpdateFee) -> Result<(), ChannelError>
                where F::Target: FeeEstimator
        {
-               if self.channel_outbound {
+               if self.is_outbound() {
                        return Err(ChannelError::Close("Non-funding remote tried to update channel fee".to_owned()));
                }
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
                        return Err(ChannelError::Close("Peer sent update_fee when we needed a channel_reestablish".to_owned()));
                }
-               Channel::<ChanSigner>::check_remote_fee(fee_estimator, msg.feerate_per_kw)?;
+               Channel::<Signer>::check_remote_fee(fee_estimator, msg.feerate_per_kw)?;
                self.pending_update_fee = Some(msg.feerate_per_kw);
                self.update_time_counter += 1;
                Ok(())
        }
 
        fn get_last_revoke_and_ack(&self) -> msgs::RevokeAndACK {
-               let next_per_commitment_point = self.holder_keys.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
-               let per_commitment_secret = self.holder_keys.release_commitment_secret(self.cur_holder_commitment_transaction_number + 2);
+               let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
+               let per_commitment_secret = self.holder_signer.release_commitment_secret(self.cur_holder_commitment_transaction_number + 2);
                msgs::RevokeAndACK {
                        channel_id: self.channel_id,
                        per_commitment_secret,
@@ -2756,7 +2907,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                if msg.next_remote_commitment_number > 0 {
                        match msg.data_loss_protect {
                                OptionalField::Present(ref data_loss) => {
-                                       let expected_point = self.holder_keys.get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - msg.next_remote_commitment_number + 1, &self.secp_ctx);
+                                       let expected_point = self.holder_signer.get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - msg.next_remote_commitment_number + 1, &self.secp_ctx);
                                        let given_secret = SecretKey::from_slice(&data_loss.your_last_per_commitment_secret)
                                                .map_err(|_| ChannelError::Close("Peer sent a garbage channel_reestablish with unparseable secret key".to_owned()))?;
                                        if expected_point != PublicKey::from_secret_key(&self.secp_ctx, &given_secret) {
@@ -2795,7 +2946,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        }
 
                        // We have OurFundingLocked set!
-                       let next_per_commitment_point = self.holder_keys.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
+                       let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
                        return Ok((Some(msgs::FundingLocked {
                                channel_id: self.channel_id(),
                                next_per_commitment_point,
@@ -2825,7 +2976,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
                let resend_funding_locked = if msg.next_local_commitment_number == 1 && INITIAL_COMMITMENT_NUMBER - self.cur_holder_commitment_transaction_number == 1 {
                        // We should never have to worry about MonitorUpdateFailed resending FundingLocked
-                       let next_per_commitment_point = self.holder_keys.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
+                       let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
                        Some(msgs::FundingLocked {
                                channel_id: self.channel_id(),
                                next_per_commitment_point,
@@ -2892,7 +3043,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        fn maybe_propose_first_closing_signed<F: Deref>(&mut self, fee_estimator: &F) -> Option<msgs::ClosingSigned>
                where F::Target: FeeEstimator
        {
-               if !self.channel_outbound || !self.pending_inbound_htlcs.is_empty() || !self.pending_outbound_htlcs.is_empty() ||
+               if !self.is_outbound() || !self.pending_inbound_htlcs.is_empty() || !self.pending_outbound_htlcs.is_empty() ||
                                self.channel_state & (BOTH_SIDES_SHUTDOWN_MASK | ChannelState::AwaitingRemoteRevoke as u32) != BOTH_SIDES_SHUTDOWN_MASK ||
                                self.last_sent_closing_fee.is_some() || self.pending_update_fee.is_some() {
                        return None;
@@ -2906,7 +3057,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                let proposed_total_fee_satoshis = proposed_feerate as u64 * tx_weight / 1000;
 
                let (closing_tx, total_fee_satoshis) = self.build_closing_transaction(proposed_total_fee_satoshis, false);
-               let sig = self.holder_keys
+               let sig = self.holder_signer
                        .sign_closing_transaction(&closing_tx, &self.secp_ctx)
                        .ok();
                assert!(closing_tx.get_weight() as u64 <= tx_weight);
@@ -2920,7 +3071,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                })
        }
 
-       pub fn shutdown<F: Deref>(&mut self, fee_estimator: &F, msg: &msgs::Shutdown) -> Result<(Option<msgs::Shutdown>, Option<msgs::ClosingSigned>, Vec<(HTLCSource, PaymentHash)>), ChannelError>
+       pub fn shutdown<F: Deref>(&mut self, fee_estimator: &F, their_features: &InitFeatures, msg: &msgs::Shutdown) -> Result<(Option<msgs::Shutdown>, Option<msgs::ClosingSigned>, Vec<(HTLCSource, PaymentHash)>), ChannelError>
                where F::Target: FeeEstimator
        {
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
@@ -2939,14 +3090,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                }
                assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
 
-               // BOLT 2 says we must only send a scriptpubkey of certain standard forms, which are up to
-               // 34 bytes in length, so don't let the remote peer feed us some super fee-heavy script.
-               if self.channel_outbound && msg.scriptpubkey.len() > 34 {
-                       return Err(ChannelError::Close(format!("Got counterparty shutdown_scriptpubkey ({}) of absurd length from remote peer", msg.scriptpubkey.to_bytes().to_hex())));
-               }
-
-               //Check counterparty_shutdown_scriptpubkey form as BOLT says we must
-               if !msg.scriptpubkey.is_p2pkh() && !msg.scriptpubkey.is_p2sh() && !msg.scriptpubkey.is_v0_p2wpkh() && !msg.scriptpubkey.is_v0_p2wsh() {
+               if is_unsupported_shutdown_script(&their_features, &msg.scriptpubkey) {
                        return Err(ChannelError::Close(format!("Got a nonstandard scriptpubkey ({}) from remote peer", msg.scriptpubkey.to_bytes().to_hex())));
                }
 
@@ -3003,7 +3147,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
                tx.input[0].witness.push(Vec::new()); // First is the multisig dummy
 
-               let funding_key = self.holder_keys.pubkeys().funding_pubkey.serialize();
+               let funding_key = self.get_holder_pubkeys().funding_pubkey.serialize();
                let counterparty_funding_key = self.counterparty_funding_pubkey().serialize();
                if funding_key[..] < counterparty_funding_key[..] {
                        tx.input[0].witness.push(sig.serialize_der().to_vec());
@@ -3041,9 +3185,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                }
                let mut sighash = hash_to_message!(&bip143::SigHashCache::new(&closing_tx).signature_hash(0, &funding_redeemscript, self.channel_value_satoshis, SigHashType::All)[..]);
 
-               let counterparty_funding_pubkey = &self.counterparty_pubkeys.as_ref().unwrap().funding_pubkey;
-
-               match self.secp_ctx.verify(&sighash, &msg.signature, counterparty_funding_pubkey) {
+               match self.secp_ctx.verify(&sighash, &msg.signature, &self.get_counterparty_pubkeys().funding_pubkey) {
                        Ok(_) => {},
                        Err(_e) => {
                                // The remote end may have decided to revoke their output due to inconsistent dust
@@ -3072,7 +3214,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        ($new_feerate: expr) => {
                                let tx_weight = self.get_closing_transaction_weight(Some(&self.get_closing_scriptpubkey()), Some(self.counterparty_shutdown_scriptpubkey.as_ref().unwrap()));
                                let (closing_tx, used_total_fee) = self.build_closing_transaction($new_feerate as u64 * tx_weight / 1000, false);
-                               let sig = self.holder_keys
+                               let sig = self.holder_signer
                                        .sign_closing_transaction(&closing_tx, &self.secp_ctx)
                                        .map_err(|_| ChannelError::Close("External signer refused to sign closing transaction".to_owned()))?;
                                assert!(closing_tx.get_weight() as u64 <= tx_weight);
@@ -3086,7 +3228,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                }
 
                let mut min_feerate = 253;
-               if self.channel_outbound {
+               if self.is_outbound() {
                        let max_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Normal);
                        if (msg.fee_satoshis as u64) > max_feerate as u64 * closing_tx_max_weight / 1000 {
                                if let Some((last_feerate, _, _)) = self.last_sent_closing_fee {
@@ -3108,7 +3250,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        propose_new_feerate!(min_feerate);
                }
 
-               let sig = self.holder_keys
+               let sig = self.holder_signer
                        .sign_closing_transaction(&closing_tx, &self.secp_ctx)
                        .map_err(|_| ChannelError::Close("External signer refused to sign closing transaction".to_owned()))?;
                self.build_signed_closing_transaction(&mut closing_tx, &msg.signature, &sig);
@@ -3147,7 +3289,23 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        /// Returns the funding_txo we either got from our peer, or were given by
        /// get_outbound_funding_created.
        pub fn get_funding_txo(&self) -> Option<OutPoint> {
-               self.funding_txo
+               self.channel_transaction_parameters.funding_outpoint
+       }
+
+       fn get_holder_selected_contest_delay(&self) -> u16 {
+               self.channel_transaction_parameters.holder_selected_contest_delay
+       }
+
+       fn get_holder_pubkeys(&self) -> &ChannelPublicKeys {
+               &self.channel_transaction_parameters.holder_pubkeys
+       }
+
+       fn get_counterparty_selected_contest_delay(&self) -> u16 {
+               self.channel_transaction_parameters.counterparty_parameters.as_ref().unwrap().selected_contest_delay
+       }
+
+       fn get_counterparty_pubkeys(&self) -> &ChannelPublicKeys {
+               &self.channel_transaction_parameters.counterparty_parameters.as_ref().unwrap().pubkeys
        }
 
        /// Allowed in any state (including after shutdown)
@@ -3169,7 +3327,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        // channel might have been used to route very small values (either by honest users or as DoS).
                        self.channel_value_satoshis * 1000 * 9 / 10,
 
-                       Channel::<ChanSigner>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis)
+                       Channel::<Signer>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis)
                );
        }
 
@@ -3204,8 +3362,8 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        }
 
        #[cfg(test)]
-       pub fn get_keys(&self) -> &ChanSigner {
-               &self.holder_keys
+       pub fn get_signer(&self) -> &Signer {
+               &self.holder_signer
        }
 
        #[cfg(test)]
@@ -3247,7 +3405,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        }
 
        pub fn is_outbound(&self) -> bool {
-               self.channel_outbound
+               self.channel_transaction_parameters.is_outbound_from_holder
        }
 
        /// Gets the fee we'd want to charge for adding an HTLC output to this Channel
@@ -3261,7 +3419,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                // the fee cost of the HTLC-Success/HTLC-Timeout transaction:
                let mut res = self.feerate_per_kw as u64 * cmp::max(HTLC_TIMEOUT_TX_WEIGHT, HTLC_SUCCESS_TX_WEIGHT) / 1000;
 
-               if self.channel_outbound {
+               if self.is_outbound() {
                        // + the marginal fee increase cost to us in the commitment transaction:
                        res += self.feerate_per_kw as u64 * COMMITMENT_TX_WEIGHT_PER_HTLC / 1000;
                }
@@ -3367,11 +3525,12 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                }
                if non_shutdown_state & !(ChannelState::TheirFundingLocked as u32) == ChannelState::FundingSent as u32 {
                        for &(index_in_block, tx) in txdata.iter() {
-                               if tx.txid() == self.funding_txo.unwrap().txid {
-                                       let txo_idx = self.funding_txo.unwrap().index as usize;
+                               let funding_txo = self.get_funding_txo().unwrap();
+                               if tx.txid() == funding_txo.txid {
+                                       let txo_idx = funding_txo.index as usize;
                                        if txo_idx >= tx.output.len() || tx.output[txo_idx].script_pubkey != self.get_funding_redeemscript().to_v0_p2wsh() ||
                                                        tx.output[txo_idx].value != self.channel_value_satoshis {
-                                               if self.channel_outbound {
+                                               if self.is_outbound() {
                                                        // If we generated the funding transaction and it doesn't match what it
                                                        // should, the client is really broken and we should just panic and
                                                        // tell them off. That said, because hash collisions happen with high
@@ -3387,7 +3546,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                                                        data: "funding tx had wrong script/value".to_owned()
                                                });
                                        } else {
-                                               if self.channel_outbound {
+                                               if self.is_outbound() {
                                                        for input in tx.input.iter() {
                                                                if input.witness.is_empty() {
                                                                        // We generated a malleable funding transaction, implying we've
@@ -3440,7 +3599,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                                        //a protocol oversight, but I assume I'm just missing something.
                                        if need_commitment_update {
                                                if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) == 0 {
-                                                       let next_per_commitment_point = self.holder_keys.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
+                                                       let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
                                                        return Ok((Some(msgs::FundingLocked {
                                                                channel_id: self.channel_id,
                                                                next_per_commitment_point,
@@ -3477,7 +3636,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        // something in the handler for the message that prompted this message):
 
        pub fn get_open_channel(&self, chain_hash: BlockHash) -> msgs::OpenChannel {
-               if !self.channel_outbound {
+               if !self.is_outbound() {
                        panic!("Tried to open a channel for an inbound channel?");
                }
                if self.channel_state != ChannelState::OurInitSent as u32 {
@@ -3488,8 +3647,8 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        panic!("Tried to send an open_channel for a channel that has already advanced");
                }
 
-               let first_per_commitment_point = self.holder_keys.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
-               let keys = self.holder_keys.pubkeys();
+               let first_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
+               let keys = self.get_holder_pubkeys();
 
                msgs::OpenChannel {
                        chain_hash,
@@ -3497,11 +3656,11 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        funding_satoshis: self.channel_value_satoshis,
                        push_msat: self.channel_value_satoshis * 1000 - self.value_to_self_msat,
                        dust_limit_satoshis: self.holder_dust_limit_satoshis,
-                       max_htlc_value_in_flight_msat: Channel::<ChanSigner>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis),
-                       channel_reserve_satoshis: Channel::<ChanSigner>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis),
+                       max_htlc_value_in_flight_msat: Channel::<Signer>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis),
+                       channel_reserve_satoshis: Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis),
                        htlc_minimum_msat: self.holder_htlc_minimum_msat,
                        feerate_per_kw: self.feerate_per_kw as u32,
-                       to_self_delay: self.holder_selected_contest_delay,
+                       to_self_delay: self.get_holder_selected_contest_delay(),
                        max_accepted_htlcs: OUR_MAX_HTLCS,
                        funding_pubkey: keys.funding_pubkey,
                        revocation_basepoint: keys.revocation_basepoint,
@@ -3515,7 +3674,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        }
 
        pub fn get_accept_channel(&self) -> msgs::AcceptChannel {
-               if self.channel_outbound {
+               if self.is_outbound() {
                        panic!("Tried to send accept_channel for an outbound channel?");
                }
                if self.channel_state != (ChannelState::OurInitSent as u32) | (ChannelState::TheirInitSent as u32) {
@@ -3525,17 +3684,17 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        panic!("Tried to send an accept_channel for a channel that has already advanced");
                }
 
-               let first_per_commitment_point = self.holder_keys.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
-               let keys = self.holder_keys.pubkeys();
+               let first_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
+               let keys = self.get_holder_pubkeys();
 
                msgs::AcceptChannel {
                        temporary_channel_id: self.channel_id,
                        dust_limit_satoshis: self.holder_dust_limit_satoshis,
-                       max_htlc_value_in_flight_msat: Channel::<ChanSigner>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis),
-                       channel_reserve_satoshis: Channel::<ChanSigner>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis),
+                       max_htlc_value_in_flight_msat: Channel::<Signer>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis),
+                       channel_reserve_satoshis: Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis),
                        htlc_minimum_msat: self.holder_htlc_minimum_msat,
                        minimum_depth: self.minimum_depth,
-                       to_self_delay: self.holder_selected_contest_delay,
+                       to_self_delay: self.get_holder_selected_contest_delay(),
                        max_accepted_htlcs: OUR_MAX_HTLCS,
                        funding_pubkey: keys.funding_pubkey,
                        revocation_basepoint: keys.revocation_basepoint,
@@ -3551,8 +3710,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        fn get_outbound_funding_created_signature<L: Deref>(&mut self, logger: &L) -> Result<Signature, ChannelError> where L::Target: Logger {
                let counterparty_keys = self.build_remote_transaction_keys()?;
                let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, self.feerate_per_kw, logger).0;
-               let pre_remote_keys = PreCalculatedTxCreationKeys::new(counterparty_keys);
-               Ok(self.holder_keys.sign_counterparty_commitment(self.feerate_per_kw, &counterparty_initial_commitment_tx, &pre_remote_keys, &Vec::new(), &self.secp_ctx)
+               Ok(self.holder_signer.sign_counterparty_commitment(&counterparty_initial_commitment_tx, &self.secp_ctx)
                                .map_err(|_| ChannelError::Close("Failed to get signatures for new commitment_signed".to_owned()))?.0)
        }
 
@@ -3564,7 +3722,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        /// Do NOT broadcast the funding transaction until after a successful funding_signed call!
        /// If an Err is returned, it is a ChannelError::Close.
        pub fn get_outbound_funding_created<L: Deref>(&mut self, funding_txo: OutPoint, logger: &L) -> Result<msgs::FundingCreated, ChannelError> where L::Target: Logger {
-               if !self.channel_outbound {
+               if !self.is_outbound() {
                        panic!("Tried to create outbound funding_created message on an inbound channel!");
                }
                if self.channel_state != (ChannelState::OurInitSent as u32 | ChannelState::TheirInitSent as u32) {
@@ -3576,12 +3734,14 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        panic!("Should not have advanced channel commitment tx numbers prior to funding_created");
                }
 
-               self.funding_txo = Some(funding_txo.clone());
+               self.channel_transaction_parameters.funding_outpoint = Some(funding_txo);
+               self.holder_signer.ready_channel(&self.channel_transaction_parameters);
+
                let signature = match self.get_outbound_funding_created_signature(logger) {
                        Ok(res) => res,
                        Err(e) => {
                                log_error!(logger, "Got bad signatures: {:?}!", e);
-                               self.funding_txo = None;
+                               self.channel_transaction_parameters.funding_outpoint = None;
                                return Err(e);
                        }
                };
@@ -3628,12 +3788,12 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        short_channel_id: self.get_short_channel_id().unwrap(),
                        node_id_1: if were_node_one { node_id } else { self.get_counterparty_node_id() },
                        node_id_2: if were_node_one { self.get_counterparty_node_id() } else { node_id },
-                       bitcoin_key_1: if were_node_one { self.holder_keys.pubkeys().funding_pubkey } else { self.counterparty_funding_pubkey().clone() },
-                       bitcoin_key_2: if were_node_one { self.counterparty_funding_pubkey().clone() } else { self.holder_keys.pubkeys().funding_pubkey },
+                       bitcoin_key_1: if were_node_one { self.get_holder_pubkeys().funding_pubkey } else { self.counterparty_funding_pubkey().clone() },
+                       bitcoin_key_2: if were_node_one { self.counterparty_funding_pubkey().clone() } else { self.get_holder_pubkeys().funding_pubkey },
                        excess_data: Vec::new(),
                };
 
-               let sig = self.holder_keys.sign_channel_announcement(&msg, &self.secp_ctx)
+               let sig = self.holder_signer.sign_channel_announcement(&msg, &self.secp_ctx)
                        .map_err(|_| ChannelError::Ignore("Signer rejected channel_announcement".to_owned()))?;
 
                Ok((msg, sig))
@@ -3736,13 +3896,12 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        return Err(ChannelError::Ignore(format!("Cannot send value that would put us over the max HTLC value in flight our peer will accept ({})", self.counterparty_max_htlc_value_in_flight_msat)));
                }
 
-               if !self.channel_outbound {
+               if !self.is_outbound() {
                        // Check that we won't violate the remote channel reserve by adding this HTLC.
-
                        let counterparty_balance_msat = self.channel_value_satoshis * 1000 - self.value_to_self_msat;
-                       let holder_selected_chan_reserve_msat = Channel::<ChanSigner>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis);
-                       // 1 additional HTLC corresponding to this HTLC.
-                       let counterparty_commit_tx_fee_msat = self.next_remote_commit_tx_fee_msat(1);
+                       let holder_selected_chan_reserve_msat = Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis);
+                       let htlc_candidate = HTLCCandidate::new(amount_msat, HTLCInitiator::LocalOffered);
+                       let counterparty_commit_tx_fee_msat = self.next_remote_commit_tx_fee_msat(htlc_candidate, None);
                        if counterparty_balance_msat < holder_selected_chan_reserve_msat + counterparty_commit_tx_fee_msat {
                                return Err(ChannelError::Ignore("Cannot send value that would put counterparty balance under holder-announced channel reserve value".to_owned()));
                        }
@@ -3753,10 +3912,10 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        return Err(ChannelError::Ignore(format!("Cannot send value that would overdraw remaining funds. Amount: {}, pending value to self {}", amount_msat, pending_value_to_self_msat)));
                }
 
-               // The `+1` is for the HTLC currently being added to the commitment tx and
-               // the `2 *` and `+1` are for the fee spike buffer.
-               let commit_tx_fee_msat = if self.channel_outbound {
-                       2 * self.next_local_commit_tx_fee_msat(1 + 1)
+               // `2 *` and extra HTLC are for the fee spike buffer.
+               let commit_tx_fee_msat = if self.is_outbound() {
+                       let htlc_candidate = HTLCCandidate::new(amount_msat, HTLCInitiator::LocalOffered);
+                       2 * self.next_local_commit_tx_fee_msat(htlc_candidate, Some(()))
                } else { 0 };
                if pending_value_to_self_msat - amount_msat < commit_tx_fee_msat {
                        return Err(ChannelError::Ignore(format!("Cannot send value that would not leave enough to pay for fees. Pending value to self: {}. local_commit_tx_fee {}", pending_value_to_self_msat, commit_tx_fee_msat)));
@@ -3860,7 +4019,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                }
                self.resend_order = RAACommitmentOrder::RevokeAndACKFirst;
 
-               let (res, counterparty_commitment_tx, htlcs) = match self.send_commitment_no_state_update(logger) {
+               let (res, counterparty_commitment_txid, htlcs) = match self.send_commitment_no_state_update(logger) {
                        Ok((res, (counterparty_commitment_tx, mut htlcs))) => {
                                // Update state now that we've passed all the can-fail calls...
                                let htlcs_no_ref: Vec<(HTLCOutputInCommitment, Option<Box<HTLCSource>>)> =
@@ -3874,7 +4033,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                let monitor_update = ChannelMonitorUpdate {
                        update_id: self.latest_monitor_update_id,
                        updates: vec![ChannelMonitorUpdateStep::LatestCounterpartyCommitmentTXInfo {
-                               unsigned_commitment_tx: counterparty_commitment_tx.clone(),
+                               commitment_txid: counterparty_commitment_txid,
                                htlc_outputs: htlcs.clone(),
                                commitment_number: self.cur_counterparty_commitment_transaction_number,
                                their_revocation_point: self.counterparty_cur_commitment_point.unwrap()
@@ -3886,40 +4045,58 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
        /// Only fails in case of bad keys. Used for channel_reestablish commitment_signed generation
        /// when we shouldn't change HTLC/channel state.
-       fn send_commitment_no_state_update<L: Deref>(&self, logger: &L) -> Result<(msgs::CommitmentSigned, (Transaction, Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)>)), ChannelError> where L::Target: Logger {
+       fn send_commitment_no_state_update<L: Deref>(&self, logger: &L) -> Result<(msgs::CommitmentSigned, (Txid, Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)>)), ChannelError> where L::Target: Logger {
                let mut feerate_per_kw = self.feerate_per_kw;
                if let Some(feerate) = self.pending_update_fee {
-                       if self.channel_outbound {
+                       if self.is_outbound() {
                                feerate_per_kw = feerate;
                        }
                }
 
                let counterparty_keys = self.build_remote_transaction_keys()?;
                let counterparty_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, true, feerate_per_kw, logger);
+               let counterparty_commitment_txid = counterparty_commitment_tx.0.trust().txid();
                let (signature, htlc_signatures);
 
+               #[cfg(any(test, feature = "fuzztarget"))]
+               {
+                       if !self.is_outbound() {
+                               let projected_commit_tx_info = self.next_remote_commitment_tx_fee_info_cached.lock().unwrap().take();
+                               *self.next_local_commitment_tx_fee_info_cached.lock().unwrap() = None;
+                               if let Some(info) = projected_commit_tx_info {
+                                       let total_pending_htlcs = self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len();
+                                       if info.total_pending_htlcs == total_pending_htlcs
+                                               && info.next_holder_htlc_id == self.next_holder_htlc_id
+                                               && info.next_counterparty_htlc_id == self.next_counterparty_htlc_id
+                                               && info.feerate == self.feerate_per_kw {
+                                                       let actual_fee = self.commit_tx_fee_msat(counterparty_commitment_tx.1);
+                                                       assert_eq!(actual_fee, info.fee);
+                                               }
+                               }
+                       }
+               }
+
                {
                        let mut htlcs = Vec::with_capacity(counterparty_commitment_tx.2.len());
                        for &(ref htlc, _) in counterparty_commitment_tx.2.iter() {
                                htlcs.push(htlc);
                        }
 
-                       let pre_remote_keys = PreCalculatedTxCreationKeys::new(counterparty_keys);
-                       let res = self.holder_keys.sign_counterparty_commitment(feerate_per_kw, &counterparty_commitment_tx.0, &pre_remote_keys, &htlcs, &self.secp_ctx)
+                       let res = self.holder_signer.sign_counterparty_commitment(&counterparty_commitment_tx.0, &self.secp_ctx)
                                .map_err(|_| ChannelError::Close("Failed to get signatures for new commitment_signed".to_owned()))?;
                        signature = res.0;
                        htlc_signatures = res.1;
-                       let counterparty_keys = pre_remote_keys.trust_key_derivation();
 
-                       log_trace!(logger, "Signed remote commitment tx {} with redeemscript {} -> {}",
-                               encode::serialize_hex(&counterparty_commitment_tx.0),
+                       log_trace!(logger, "Signed remote commitment tx {} (txid {}) with redeemscript {} -> {}",
+                               encode::serialize_hex(&counterparty_commitment_tx.0.trust().built_transaction().transaction),
+                               &counterparty_commitment_txid,
                                encode::serialize_hex(&self.get_funding_redeemscript()),
                                log_bytes!(signature.serialize_compact()[..]));
 
                        for (ref htlc_sig, ref htlc) in htlc_signatures.iter().zip(htlcs) {
                                log_trace!(logger, "Signed remote HTLC tx {} with redeemscript {} with pubkey {} -> {}",
-                                       encode::serialize_hex(&chan_utils::build_htlc_transaction(&counterparty_commitment_tx.0.txid(), feerate_per_kw, self.holder_selected_contest_delay, htlc, &counterparty_keys.broadcaster_delayed_payment_key, &counterparty_keys.revocation_key)),
-                                       encode::serialize_hex(&chan_utils::get_htlc_redeemscript(&htlc, counterparty_keys)),
+                                       encode::serialize_hex(&chan_utils::build_htlc_transaction(&counterparty_commitment_txid, feerate_per_kw, self.get_holder_selected_contest_delay(), htlc, &counterparty_keys.broadcaster_delayed_payment_key, &counterparty_keys.revocation_key)),
+                                       encode::serialize_hex(&chan_utils::get_htlc_redeemscript(&htlc, &counterparty_keys)),
                                        log_bytes!(counterparty_keys.broadcaster_htlc_key.serialize()),
                                        log_bytes!(htlc_sig.serialize_compact()[..]));
                        }
@@ -3929,7 +4106,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                        channel_id: self.channel_id,
                        signature,
                        htlc_signatures,
-               }, (counterparty_commitment_tx.0, counterparty_commitment_tx.2)))
+               }, (counterparty_commitment_txid, counterparty_commitment_tx.2)))
        }
 
        /// Adds a pending outbound HTLC to this channel, and creates a signed commitment transaction
@@ -4016,7 +4193,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
                                _ => {}
                        }
                }
-               let funding_txo = if let Some(funding_txo) = self.funding_txo {
+               let funding_txo = if let Some(funding_txo) = self.get_funding_txo() {
                        // If we haven't yet exchanged funding signatures (ie channel_state < FundingSent),
                        // returning a channel monitor update here would imply a channel monitor update before
                        // we even registered the channel monitor to begin with, which is invalid.
@@ -4039,6 +4216,24 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
        }
 }
 
+fn is_unsupported_shutdown_script(their_features: &InitFeatures, script: &Script) -> bool {
+       // We restrain shutdown scripts to standards forms to avoid transactions not propagating on the p2p tx-relay network
+
+       // BOLT 2 says we must only send a scriptpubkey of certain standard forms,
+       // which for a a BIP-141-compliant witness program is at max 42 bytes in length.
+       // So don't let the remote peer feed us some super fee-heavy script.
+       let is_script_too_long = script.len() > 42;
+       if is_script_too_long {
+               return true;
+       }
+
+       if their_features.supports_shutdown_anysegwit() && script.is_witness_program() && script.as_bytes()[0] != OP_PUSHBYTES_0.into_u8() {
+               return false;
+       }
+
+       return !script.is_p2pkh() && !script.is_p2sh() && !script.is_v0_p2wpkh() && !script.is_v0_p2wsh()
+}
+
 const SERIALIZATION_VERSION: u8 = 1;
 const MIN_SERIALIZATION_VERSION: u8 = 1;
 
@@ -4074,7 +4269,7 @@ impl Readable for InboundHTLCRemovalReason {
        }
 }
 
-impl<ChanSigner: ChannelKeys + Writeable> Writeable for Channel<ChanSigner> {
+impl<Signer: Sign> Writeable for Channel<Signer> {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                // Note that we write out as if remove_uncommitted_htlcs_and_mark_paused had just been
                // called but include holding cell updates (and obviously we don't modify self).
@@ -4087,12 +4282,17 @@ impl<ChanSigner: ChannelKeys + Writeable> Writeable for Channel<ChanSigner> {
 
                self.channel_id.write(writer)?;
                (self.channel_state | ChannelState::PeerDisconnected as u32).write(writer)?;
-               self.channel_outbound.write(writer)?;
                self.channel_value_satoshis.write(writer)?;
 
                self.latest_monitor_update_id.write(writer)?;
 
-               self.holder_keys.write(writer)?;
+               let mut key_data = VecWriter(Vec::new());
+               self.holder_signer.write(&mut key_data)?;
+               assert!(key_data.0.len() < std::usize::MAX);
+               assert!(key_data.0.len() < std::u32::MAX as usize);
+               (key_data.0.len() as u32).write(writer)?;
+               writer.write_all(&key_data.0[..])?;
+
                self.shutdown_pubkey.write(writer)?;
                self.destination_script.write(writer)?;
 
@@ -4229,7 +4429,6 @@ impl<ChanSigner: ChannelKeys + Writeable> Writeable for Channel<ChanSigner> {
                        None => 0u8.write(writer)?,
                }
 
-               self.funding_txo.write(writer)?;
                self.funding_tx_confirmed_in.write(writer)?;
                self.short_channel_id.write(writer)?;
 
@@ -4242,12 +4441,10 @@ impl<ChanSigner: ChannelKeys + Writeable> Writeable for Channel<ChanSigner> {
                self.counterparty_selected_channel_reserve_satoshis.write(writer)?;
                self.counterparty_htlc_minimum_msat.write(writer)?;
                self.holder_htlc_minimum_msat.write(writer)?;
-               self.counterparty_selected_contest_delay.write(writer)?;
-               self.holder_selected_contest_delay.write(writer)?;
                self.counterparty_max_accepted_htlcs.write(writer)?;
                self.minimum_depth.write(writer)?;
 
-               self.counterparty_pubkeys.write(writer)?;
+               self.channel_transaction_parameters.write(writer)?;
                self.counterparty_cur_commitment_point.write(writer)?;
 
                self.counterparty_prev_commitment_point.write(writer)?;
@@ -4260,8 +4457,10 @@ impl<ChanSigner: ChannelKeys + Writeable> Writeable for Channel<ChanSigner> {
        }
 }
 
-impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
-       fn read<R : ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+const MAX_ALLOC_SIZE: usize = 64*1024;
+impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
+               where K::Target: KeysInterface<Signer = Signer> {
+       fn read<R : ::std::io::Read>(reader: &mut R, keys_source: &'a K) -> Result<Self, DecodeError> {
                let _ver: u8 = Readable::read(reader)?;
                let min_ver: u8 = Readable::read(reader)?;
                if min_ver > SERIALIZATION_VERSION {
@@ -4273,12 +4472,21 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
 
                let channel_id = Readable::read(reader)?;
                let channel_state = Readable::read(reader)?;
-               let channel_outbound = Readable::read(reader)?;
                let channel_value_satoshis = Readable::read(reader)?;
 
                let latest_monitor_update_id = Readable::read(reader)?;
 
-               let holder_keys = Readable::read(reader)?;
+               let keys_len: u32 = Readable::read(reader)?;
+               let mut keys_data = Vec::with_capacity(cmp::min(keys_len as usize, MAX_ALLOC_SIZE));
+               while keys_data.len() != keys_len as usize {
+                       // Read 1KB at a time to avoid accidentally allocating 4GB on corrupted channel keys
+                       let mut data = [0; 1024];
+                       let read_slice = &mut data[0..cmp::min(1024, keys_len as usize - keys_data.len())];
+                       reader.read_exact(read_slice)?;
+                       keys_data.extend_from_slice(read_slice);
+               }
+               let holder_signer = keys_source.read_chan_signer(&keys_data)?;
+
                let shutdown_pubkey = Readable::read(reader)?;
                let destination_script = Readable::read(reader)?;
 
@@ -4383,7 +4591,6 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
                        _ => return Err(DecodeError::InvalidValue),
                };
 
-               let funding_txo = Readable::read(reader)?;
                let funding_tx_confirmed_in = Readable::read(reader)?;
                let short_channel_id = Readable::read(reader)?;
 
@@ -4396,12 +4603,10 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
                let counterparty_selected_channel_reserve_satoshis = Readable::read(reader)?;
                let counterparty_htlc_minimum_msat = Readable::read(reader)?;
                let holder_htlc_minimum_msat = Readable::read(reader)?;
-               let counterparty_selected_contest_delay = Readable::read(reader)?;
-               let holder_selected_contest_delay = Readable::read(reader)?;
                let counterparty_max_accepted_htlcs = Readable::read(reader)?;
                let minimum_depth = Readable::read(reader)?;
 
-               let counterparty_pubkeys = Readable::read(reader)?;
+               let channel_parameters = Readable::read(reader)?;
                let counterparty_cur_commitment_point = Readable::read(reader)?;
 
                let counterparty_prev_commitment_point = Readable::read(reader)?;
@@ -4410,19 +4615,21 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
                let counterparty_shutdown_scriptpubkey = Readable::read(reader)?;
                let commitment_secrets = Readable::read(reader)?;
 
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&keys_source.get_secure_random_bytes());
+
                Ok(Channel {
                        user_id,
 
                        config,
                        channel_id,
                        channel_state,
-                       channel_outbound,
-                       secp_ctx: Secp256k1::new(),
+                       secp_ctx,
                        channel_value_satoshis,
 
                        latest_monitor_update_id,
 
-                       holder_keys,
+                       holder_signer,
                        shutdown_pubkey,
                        destination_script,
 
@@ -4456,7 +4663,6 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
 
                        last_sent_closing_fee,
 
-                       funding_txo,
                        funding_tx_confirmed_in,
                        short_channel_id,
                        last_block_connected,
@@ -4468,12 +4674,10 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
                        counterparty_selected_channel_reserve_satoshis,
                        counterparty_htlc_minimum_msat,
                        holder_htlc_minimum_msat,
-                       counterparty_selected_contest_delay,
-                       holder_selected_contest_delay,
                        counterparty_max_accepted_htlcs,
                        minimum_depth,
 
-                       counterparty_pubkeys,
+                       channel_transaction_parameters: channel_parameters,
                        counterparty_cur_commitment_point,
 
                        counterparty_prev_commitment_point,
@@ -4484,6 +4688,11 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
                        commitment_secrets,
 
                        network_sync: UpdateStatus::Fresh,
+
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       next_local_commitment_tx_fee_info_cached: Mutex::new(None),
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
                })
        }
 }
@@ -4500,17 +4709,17 @@ mod tests {
        use bitcoin::hashes::hex::FromHex;
        use hex;
        use ln::channelmanager::{HTLCSource, PaymentPreimage, PaymentHash};
-       use ln::channel::{Channel,ChannelKeys,InboundHTLCOutput,OutboundHTLCOutput,InboundHTLCState,OutboundHTLCState,HTLCOutputInCommitment,TxCreationKeys};
+       use ln::channel::{Channel,Sign,InboundHTLCOutput,OutboundHTLCOutput,InboundHTLCState,OutboundHTLCState,HTLCOutputInCommitment,HTLCCandidate,HTLCInitiator,TxCreationKeys};
        use ln::channel::MAX_FUNDING_SATOSHIS;
        use ln::features::InitFeatures;
-       use ln::msgs::{OptionalField, DataLossProtect};
+       use ln::msgs::{OptionalField, DataLossProtect, DecodeError};
        use ln::chan_utils;
-       use ln::chan_utils::{HolderCommitmentTransaction, ChannelPublicKeys};
+       use ln::chan_utils::{ChannelPublicKeys, HolderCommitmentTransaction, CounterpartyChannelTransactionParameters, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT};
        use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
-       use chain::keysinterface::{InMemoryChannelKeys, KeysInterface};
+       use chain::keysinterface::{InMemorySigner, KeysInterface};
        use chain::transaction::OutPoint;
        use util::config::UserConfig;
-       use util::enforcing_trait_impls::EnforcingChannelKeys;
+       use util::enforcing_trait_impls::EnforcingSigner;
        use util::test_utils;
        use util::logger::Logger;
        use bitcoin::secp256k1::{Secp256k1, Message, Signature, All};
@@ -4536,10 +4745,10 @@ mod tests {
        }
 
        struct Keys {
-               chan_keys: InMemoryChannelKeys,
+               signer: InMemorySigner,
        }
        impl KeysInterface for Keys {
-               type ChanKeySigner = InMemoryChannelKeys;
+               type Signer = InMemorySigner;
 
                fn get_node_secret(&self) -> SecretKey { panic!(); }
                fn get_destination_script(&self) -> Script {
@@ -4555,10 +4764,11 @@ mod tests {
                        PublicKey::from_secret_key(&secp_ctx, &channel_close_key)
                }
 
-               fn get_channel_keys(&self, _inbound: bool, _channel_value_satoshis: u64) -> InMemoryChannelKeys {
-                       self.chan_keys.clone()
+               fn get_channel_signer(&self, _inbound: bool, _channel_value_satoshis: u64) -> InMemorySigner {
+                       self.signer.clone()
                }
                fn get_secure_random_bytes(&self) -> [u8; 32] { [0; 32] }
+               fn read_chan_signer(&self, _data: &[u8]) -> Result<Self::Signer, DecodeError> { panic!(); }
        }
 
        fn public_from_secret_hex(secp_ctx: &Secp256k1<All>, hex: &str) -> PublicKey {
@@ -4578,7 +4788,7 @@ mod tests {
 
                let node_a_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                let config = UserConfig::default();
-               let node_a_chan = Channel::<EnforcingChannelKeys>::new_outbound(&&fee_est, &&keys_provider, node_a_node_id, 10000000, 100000, 42, &config).unwrap();
+               let node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&fee_est, &&keys_provider, node_a_node_id, 10000000, 100000, 42, &config).unwrap();
 
                // Now change the fee so we can check that the fee in the open_channel message is the
                // same as the old fee.
@@ -4587,6 +4797,122 @@ mod tests {
                assert_eq!(open_channel_msg.feerate_per_kw, original_fee);
        }
 
+       #[test]
+       fn test_holder_vs_counterparty_dust_limit() {
+               // Test that when calculating the local and remote commitment transaction fees, the correct
+               // dust limits are used.
+               let feeest = TestFeeEstimator{fee_est: 15000};
+               let secp_ctx = Secp256k1::new();
+               let seed = [42; 32];
+               let network = Network::Testnet;
+               let keys_provider = test_utils::TestKeysInterface::new(&seed, network);
+
+               // Go through the flow of opening a channel between two nodes, making sure
+               // they have different dust limits.
+
+               // Create Node A's channel pointing to Node B's pubkey
+               let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
+               let config = UserConfig::default();
+               let mut node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, 10000000, 100000, 42, &config).unwrap();
+
+               // Create Node B's channel by receiving Node A's open_channel message
+               // Make sure A's dust limit is as we expect.
+               let open_channel_msg = node_a_chan.get_open_channel(genesis_block(network).header.block_hash());
+               assert_eq!(open_channel_msg.dust_limit_satoshis, 1560);
+               let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[7; 32]).unwrap());
+               let node_b_chan = Channel::<EnforcingSigner>::new_from_req(&&feeest, &&keys_provider, node_b_node_id, InitFeatures::known(), &open_channel_msg, 7, &config).unwrap();
+
+               // Node B --> Node A: accept channel, explicitly setting B's dust limit.
+               let mut accept_channel_msg = node_b_chan.get_accept_channel();
+               accept_channel_msg.dust_limit_satoshis = 546;
+               node_a_chan.accept_channel(&accept_channel_msg, &config, InitFeatures::known()).unwrap();
+
+               // Put some inbound and outbound HTLCs in A's channel.
+               let htlc_amount_msat = 11_092_000; // put an amount below A's effective dust limit but above B's.
+               node_a_chan.pending_inbound_htlcs.push(InboundHTLCOutput {
+                       htlc_id: 0,
+                       amount_msat: htlc_amount_msat,
+                       payment_hash: PaymentHash(Sha256::hash(&[42; 32]).into_inner()),
+                       cltv_expiry: 300000000,
+                       state: InboundHTLCState::Committed,
+               });
+
+               node_a_chan.pending_outbound_htlcs.push(OutboundHTLCOutput {
+                       htlc_id: 1,
+                       amount_msat: htlc_amount_msat, // put an amount below A's dust amount but above B's.
+                       payment_hash: PaymentHash(Sha256::hash(&[43; 32]).into_inner()),
+                       cltv_expiry: 200000000,
+                       state: OutboundHTLCState::Committed,
+                       source: HTLCSource::OutboundRoute {
+                               path: Vec::new(),
+                               session_priv: SecretKey::from_slice(&hex::decode("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap(),
+                               first_hop_htlc_msat: 548,
+                       }
+               });
+
+               // Make sure when Node A calculates their local commitment transaction, none of the HTLCs pass
+               // the dust limit check.
+               let htlc_candidate = HTLCCandidate::new(htlc_amount_msat, HTLCInitiator::LocalOffered);
+               let local_commit_tx_fee = node_a_chan.next_local_commit_tx_fee_msat(htlc_candidate, None);
+               let local_commit_fee_0_htlcs = node_a_chan.commit_tx_fee_msat(0);
+               assert_eq!(local_commit_tx_fee, local_commit_fee_0_htlcs);
+
+               // Finally, make sure that when Node A calculates the remote's commitment transaction fees, all
+               // of the HTLCs are seen to be above the dust limit.
+               node_a_chan.channel_transaction_parameters.is_outbound_from_holder = false;
+               let remote_commit_fee_3_htlcs = node_a_chan.commit_tx_fee_msat(3);
+               let htlc_candidate = HTLCCandidate::new(htlc_amount_msat, HTLCInitiator::LocalOffered);
+               let remote_commit_tx_fee = node_a_chan.next_remote_commit_tx_fee_msat(htlc_candidate, None);
+               assert_eq!(remote_commit_tx_fee, remote_commit_fee_3_htlcs);
+       }
+
+       #[test]
+       fn test_timeout_vs_success_htlc_dust_limit() {
+               // Make sure that when `next_remote_commit_tx_fee_msat` and `next_local_commit_tx_fee_msat`
+               // calculate the real dust limits for HTLCs (i.e. the dust limit given by the counterparty
+               // *plus* the fees paid for the HTLC) they don't swap `HTLC_SUCCESS_TX_WEIGHT` for
+               // `HTLC_TIMEOUT_TX_WEIGHT`, and vice versa.
+               let fee_est = TestFeeEstimator{fee_est: 253 };
+               let secp_ctx = Secp256k1::new();
+               let seed = [42; 32];
+               let network = Network::Testnet;
+               let keys_provider = test_utils::TestKeysInterface::new(&seed, network);
+
+               let node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
+               let config = UserConfig::default();
+               let mut chan = Channel::<EnforcingSigner>::new_outbound(&&fee_est, &&keys_provider, node_id, 10000000, 100000, 42, &config).unwrap();
+
+               let commitment_tx_fee_0_htlcs = chan.commit_tx_fee_msat(0);
+               let commitment_tx_fee_1_htlc = chan.commit_tx_fee_msat(1);
+
+               // If HTLC_SUCCESS_TX_WEIGHT and HTLC_TIMEOUT_TX_WEIGHT were swapped: then this HTLC would be
+               // counted as dust when it shouldn't be.
+               let htlc_amt_above_timeout = ((253 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + chan.holder_dust_limit_satoshis + 1) * 1000;
+               let htlc_candidate = HTLCCandidate::new(htlc_amt_above_timeout, HTLCInitiator::LocalOffered);
+               let commitment_tx_fee = chan.next_local_commit_tx_fee_msat(htlc_candidate, None);
+               assert_eq!(commitment_tx_fee, commitment_tx_fee_1_htlc);
+
+               // If swapped: this HTLC would be counted as non-dust when it shouldn't be.
+               let dust_htlc_amt_below_success = ((253 * HTLC_SUCCESS_TX_WEIGHT / 1000) + chan.holder_dust_limit_satoshis - 1) * 1000;
+               let htlc_candidate = HTLCCandidate::new(dust_htlc_amt_below_success, HTLCInitiator::RemoteOffered);
+               let commitment_tx_fee = chan.next_local_commit_tx_fee_msat(htlc_candidate, None);
+               assert_eq!(commitment_tx_fee, commitment_tx_fee_0_htlcs);
+
+               chan.channel_transaction_parameters.is_outbound_from_holder = false;
+
+               // If swapped: this HTLC would be counted as non-dust when it shouldn't be.
+               let dust_htlc_amt_above_timeout = ((253 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + chan.counterparty_dust_limit_satoshis + 1) * 1000;
+               let htlc_candidate = HTLCCandidate::new(dust_htlc_amt_above_timeout, HTLCInitiator::LocalOffered);
+               let commitment_tx_fee = chan.next_remote_commit_tx_fee_msat(htlc_candidate, None);
+               assert_eq!(commitment_tx_fee, commitment_tx_fee_0_htlcs);
+
+               // If swapped: this HTLC would be counted as dust when it shouldn't be.
+               let htlc_amt_below_success = ((253 * HTLC_SUCCESS_TX_WEIGHT / 1000) + chan.counterparty_dust_limit_satoshis - 1) * 1000;
+               let htlc_candidate = HTLCCandidate::new(htlc_amt_below_success, HTLCInitiator::RemoteOffered);
+               let commitment_tx_fee = chan.next_remote_commit_tx_fee_msat(htlc_candidate, None);
+               assert_eq!(commitment_tx_fee, commitment_tx_fee_1_htlc);
+       }
+
        #[test]
        fn channel_reestablish_no_updates() {
                let feeest = TestFeeEstimator{fee_est: 15000};
@@ -4601,12 +4927,12 @@ mod tests {
                // Create Node A's channel pointing to Node B's pubkey
                let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                let config = UserConfig::default();
-               let mut node_a_chan = Channel::<EnforcingChannelKeys>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, 10000000, 100000, 42, &config).unwrap();
+               let mut node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, 10000000, 100000, 42, &config).unwrap();
 
                // Create Node B's channel by receiving Node A's open_channel message
                let open_channel_msg = node_a_chan.get_open_channel(genesis_block(network).header.block_hash());
                let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[7; 32]).unwrap());
-               let mut node_b_chan = Channel::<EnforcingChannelKeys>::new_from_req(&&feeest, &&keys_provider, node_b_node_id, InitFeatures::known(), &open_channel_msg, 7, &config).unwrap();
+               let mut node_b_chan = Channel::<EnforcingSigner>::new_from_req(&&feeest, &&keys_provider, node_b_node_id, InitFeatures::known(), &open_channel_msg, 7, &config).unwrap();
 
                // Node B --> Node A: accept channel
                let accept_channel_msg = node_b_chan.get_accept_channel();
@@ -4658,7 +4984,7 @@ mod tests {
                let logger : Arc<Logger> = Arc::new(test_utils::TestLogger::new());
                let secp_ctx = Secp256k1::new();
 
-               let mut chan_keys = InMemoryChannelKeys::new(
+               let mut signer = InMemorySigner::new(
                        &secp_ctx,
                        SecretKey::from_slice(&hex::decode("30ff4956bbdd3222d44cc5e8a1261dab1e07957bdac5ae88fe3261ef321f3749").unwrap()[..]).unwrap(),
                        SecretKey::from_slice(&hex::decode("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap(),
@@ -4669,22 +4995,20 @@ mod tests {
                        // These aren't set in the test vectors:
                        [0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff],
                        10_000_000,
-                       (0, 0)
+                       [0; 32]
                );
 
-               assert_eq!(chan_keys.pubkeys().funding_pubkey.serialize()[..],
+               assert_eq!(signer.pubkeys().funding_pubkey.serialize()[..],
                                hex::decode("023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb").unwrap()[..]);
-               let keys_provider = Keys { chan_keys: chan_keys.clone() };
+               let keys_provider = Keys { signer: signer.clone() };
 
                let counterparty_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                let mut config = UserConfig::default();
                config.channel_options.announced_channel = false;
-               let mut chan = Channel::<InMemoryChannelKeys>::new_outbound(&&feeest, &&keys_provider, counterparty_node_id, 10_000_000, 100000, 42, &config).unwrap(); // Nothing uses their network key in this test
-               chan.counterparty_selected_contest_delay = 144;
+               let mut chan = Channel::<InMemorySigner>::new_outbound(&&feeest, &&keys_provider, counterparty_node_id, 10_000_000, 100000, 42, &config).unwrap(); // Nothing uses their network key in this test
                chan.holder_dust_limit_satoshis = 546;
 
                let funding_info = OutPoint{ txid: Txid::from_hex("8984484a580b825b9972d7adb15050b3ab624ccd731946b3eeddb92f4e7ef6be").unwrap(), index: 0 };
-               chan.funding_txo = Some(funding_info);
 
                let counterparty_pubkeys = ChannelPublicKeys {
                        funding_pubkey: public_from_secret_hex(&secp_ctx, "1552dfba4f6cf29a62a0af13c8d6981d36d0ef8d61ba10fb0fe90da7634d7e13"),
@@ -4693,7 +5017,13 @@ mod tests {
                        delayed_payment_basepoint: public_from_secret_hex(&secp_ctx, "1552dfba4f6cf29a62a0af13c8d6981d36d0ef8d61ba10fb0fe90da7634d7e13"),
                        htlc_basepoint: public_from_secret_hex(&secp_ctx, "4444444444444444444444444444444444444444444444444444444444444444")
                };
-               chan_keys.on_accept(&counterparty_pubkeys, chan.counterparty_selected_contest_delay, chan.holder_selected_contest_delay);
+               chan.channel_transaction_parameters.counterparty_parameters = Some(
+                       CounterpartyChannelTransactionParameters {
+                               pubkeys: counterparty_pubkeys.clone(),
+                               selected_contest_delay: 144
+                       });
+               chan.channel_transaction_parameters.funding_outpoint = Some(funding_info);
+               signer.ready_channel(&chan.channel_transaction_parameters);
 
                assert_eq!(counterparty_pubkeys.payment_point.serialize()[..],
                           hex::decode("032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991").unwrap()[..]);
@@ -4707,56 +5037,64 @@ mod tests {
                // We can't just use build_holder_transaction_keys here as the per_commitment_secret is not
                // derived from a commitment_seed, so instead we copy it here and call
                // build_commitment_transaction.
-               let delayed_payment_base = &chan.holder_keys.pubkeys().delayed_payment_basepoint;
+               let delayed_payment_base = &chan.holder_signer.pubkeys().delayed_payment_basepoint;
                let per_commitment_secret = SecretKey::from_slice(&hex::decode("1f1e1d1c1b1a191817161514131211100f0e0d0c0b0a09080706050403020100").unwrap()[..]).unwrap();
                let per_commitment_point = PublicKey::from_secret_key(&secp_ctx, &per_commitment_secret);
-               let htlc_basepoint = &chan.holder_keys.pubkeys().htlc_basepoint;
+               let htlc_basepoint = &chan.holder_signer.pubkeys().htlc_basepoint;
                let keys = TxCreationKeys::derive_new(&secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &counterparty_pubkeys.revocation_basepoint, &counterparty_pubkeys.htlc_basepoint).unwrap();
 
-               chan.counterparty_pubkeys = Some(counterparty_pubkeys);
-
-               let mut unsigned_tx: (Transaction, Vec<HTLCOutputInCommitment>);
-
-               let mut holdertx;
                macro_rules! test_commitment {
                        ( $counterparty_sig_hex: expr, $sig_hex: expr, $tx_hex: expr, {
                                $( { $htlc_idx: expr, $counterparty_htlc_sig_hex: expr, $htlc_sig_hex: expr, $htlc_tx_hex: expr } ), *
                        } ) => { {
-                               unsigned_tx = {
+                               let (commitment_tx, htlcs): (_, Vec<HTLCOutputInCommitment>) = {
                                        let mut res = chan.build_commitment_transaction(0xffffffffffff - 42, &keys, true, false, chan.feerate_per_kw, &logger);
+
                                        let htlcs = res.2.drain(..)
                                                .filter_map(|(htlc, _)| if htlc.transaction_output_index.is_some() { Some(htlc) } else { None })
                                                .collect();
                                        (res.0, htlcs)
                                };
+                               let trusted_tx = commitment_tx.trust();
+                               let unsigned_tx = trusted_tx.built_transaction();
                                let redeemscript = chan.get_funding_redeemscript();
                                let counterparty_signature = Signature::from_der(&hex::decode($counterparty_sig_hex).unwrap()[..]).unwrap();
-                               let sighash = Message::from_slice(&bip143::SigHashCache::new(&unsigned_tx.0).signature_hash(0, &redeemscript, chan.channel_value_satoshis, SigHashType::All)[..]).unwrap();
+                               let sighash = unsigned_tx.get_sighash_all(&redeemscript, chan.channel_value_satoshis);
                                secp_ctx.verify(&sighash, &counterparty_signature, chan.counterparty_funding_pubkey()).unwrap();
 
-                               let mut per_htlc = Vec::new();
+                               let mut per_htlc: Vec<(HTLCOutputInCommitment, Option<Signature>)> = Vec::new();
                                per_htlc.clear(); // Don't warn about excess mut for no-HTLC calls
+                               let mut counterparty_htlc_sigs = Vec::new();
+                               counterparty_htlc_sigs.clear(); // Don't warn about excess mut for no-HTLC calls
                                $({
                                        let remote_signature = Signature::from_der(&hex::decode($counterparty_htlc_sig_hex).unwrap()[..]).unwrap();
-                                       per_htlc.push((unsigned_tx.1[$htlc_idx].clone(), Some(remote_signature)));
+                                       per_htlc.push((htlcs[$htlc_idx].clone(), Some(remote_signature)));
+                                       counterparty_htlc_sigs.push(remote_signature);
                                })*
-                               assert_eq!(unsigned_tx.1.len(), per_htlc.len());
+                               assert_eq!(htlcs.len(), per_htlc.len());
 
-                               holdertx = HolderCommitmentTransaction::new_missing_holder_sig(unsigned_tx.0.clone(), counterparty_signature.clone(), &chan_keys.pubkeys().funding_pubkey, chan.counterparty_funding_pubkey(), keys.clone(), chan.feerate_per_kw, per_htlc);
-                               let holder_sig = chan_keys.sign_holder_commitment(&holdertx, &chan.secp_ctx).unwrap();
-                               assert_eq!(Signature::from_der(&hex::decode($sig_hex).unwrap()[..]).unwrap(), holder_sig);
+                               let holder_commitment_tx = HolderCommitmentTransaction::new(
+                                       commitment_tx.clone(),
+                                       counterparty_signature,
+                                       counterparty_htlc_sigs,
+                                       &chan.holder_signer.pubkeys().funding_pubkey,
+                                       chan.counterparty_funding_pubkey()
+                               );
+                               let (holder_sig, htlc_sigs) = signer.sign_holder_commitment_and_htlcs(&holder_commitment_tx, &secp_ctx).unwrap();
+                               assert_eq!(Signature::from_der(&hex::decode($sig_hex).unwrap()[..]).unwrap(), holder_sig, "holder_sig");
 
-                               assert_eq!(serialize(&holdertx.add_holder_sig(&redeemscript, holder_sig))[..],
-                                               hex::decode($tx_hex).unwrap()[..]);
+                               let funding_redeemscript = chan.get_funding_redeemscript();
+                               let tx = holder_commitment_tx.add_holder_sig(&funding_redeemscript, holder_sig);
+                               assert_eq!(serialize(&tx)[..], hex::decode($tx_hex).unwrap()[..], "tx");
 
-                               let htlc_sigs = chan_keys.sign_holder_commitment_htlc_transactions(&holdertx, &chan.secp_ctx).unwrap();
-                               let mut htlc_sig_iter = holdertx.per_htlc.iter().zip(htlc_sigs.iter().enumerate());
+                               // ((htlc, counterparty_sig), (index, holder_sig))
+                               let mut htlc_sig_iter = holder_commitment_tx.htlcs().iter().zip(&holder_commitment_tx.counterparty_htlc_sigs).zip(htlc_sigs.iter().enumerate());
 
                                $({
                                        let remote_signature = Signature::from_der(&hex::decode($counterparty_htlc_sig_hex).unwrap()[..]).unwrap();
 
-                                       let ref htlc = unsigned_tx.1[$htlc_idx];
-                                       let htlc_tx = chan.build_htlc_transaction(&unsigned_tx.0.txid(), &htlc, true, &keys, chan.feerate_per_kw);
+                                       let ref htlc = htlcs[$htlc_idx];
+                                       let htlc_tx = chan.build_htlc_transaction(&unsigned_tx.txid, &htlc, true, &keys, chan.feerate_per_kw);
                                        let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
                                        let htlc_sighash = Message::from_slice(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, SigHashType::All)[..]).unwrap();
                                        secp_ctx.verify(&htlc_sighash, &remote_signature, &keys.countersignatory_htlc_key).unwrap();
@@ -4773,20 +5111,18 @@ mod tests {
                                                assert!(preimage.is_some());
                                        }
 
-                                       let mut htlc_sig = htlc_sig_iter.next().unwrap();
-                                       while (htlc_sig.1).1.is_none() { htlc_sig = htlc_sig_iter.next().unwrap(); }
-                                       assert_eq!((htlc_sig.0).0.transaction_output_index, Some($htlc_idx));
+                                       let htlc_sig = htlc_sig_iter.next().unwrap();
+                                       assert_eq!((htlc_sig.0).0.transaction_output_index, Some($htlc_idx), "output index");
 
                                        let signature = Signature::from_der(&hex::decode($htlc_sig_hex).unwrap()[..]).unwrap();
-                                       assert_eq!(Some(signature), *(htlc_sig.1).1);
-                                       assert_eq!(serialize(&holdertx.get_signed_htlc_tx((htlc_sig.1).0, &(htlc_sig.1).1.unwrap(), &preimage, chan.counterparty_selected_contest_delay))[..],
-                                                       hex::decode($htlc_tx_hex).unwrap()[..]);
+                                       assert_eq!(signature, *(htlc_sig.1).1, "htlc sig");
+                                       let index = (htlc_sig.1).0;
+                                       let channel_parameters = chan.channel_transaction_parameters.as_holder_broadcastable();
+                                       let trusted_tx = holder_commitment_tx.trust();
+                                       assert_eq!(serialize(&trusted_tx.get_signed_htlc_tx(&channel_parameters, index, &(htlc_sig.0).1, (htlc_sig.1).1, &preimage))[..],
+                                                       hex::decode($htlc_tx_hex).unwrap()[..], "htlc tx");
                                })*
-                               loop {
-                                       let htlc_sig = htlc_sig_iter.next();
-                                       if htlc_sig.is_none() { break; }
-                                       assert!((htlc_sig.unwrap().1).1.is_none());
-                               }
+                               assert!(htlc_sig_iter.next().is_none());
                        } }
                }
 
@@ -5126,6 +5462,65 @@ mod tests {
                test_commitment!("304402202ade0142008309eb376736575ad58d03e5b115499709c6db0b46e36ff394b492022037b63d78d66404d6504d4c4ac13be346f3d1802928a6d3ad95a6a944227161a2",
                                 "304402207e8d51e0c570a5868a78414f4e0cbfaed1106b171b9581542c30718ee4eb95ba02203af84194c97adf98898c9afe2f2ed4a7f8dba05a2dfab28ac9d9c604aa49a379",
                                 "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", {});
+
+               // commitment tx with 3 htlc outputs, 2 offered having the same amount and preimage
+               chan.value_to_self_msat = 7_000_000_000 - 2_000_000;
+               chan.feerate_per_kw = 253;
+               chan.pending_inbound_htlcs.clear();
+               chan.pending_inbound_htlcs.push({
+                       let mut out = InboundHTLCOutput{
+                               htlc_id: 1,
+                               amount_msat: 2000000,
+                               cltv_expiry: 501,
+                               payment_hash: PaymentHash([0; 32]),
+                               state: InboundHTLCState::Committed,
+                       };
+                       out.payment_hash.0 = Sha256::hash(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()).into_inner();
+                       out
+               });
+               chan.pending_outbound_htlcs.clear();
+               chan.pending_outbound_htlcs.push({
+                       let mut out = OutboundHTLCOutput{
+                               htlc_id: 6,
+                               amount_msat: 5000000,
+                               cltv_expiry: 506,
+                               payment_hash: PaymentHash([0; 32]),
+                               state: OutboundHTLCState::Committed,
+                               source: HTLCSource::dummy(),
+                       };
+                       out.payment_hash.0 = Sha256::hash(&hex::decode("0505050505050505050505050505050505050505050505050505050505050505").unwrap()).into_inner();
+                       out
+               });
+               chan.pending_outbound_htlcs.push({
+                       let mut out = OutboundHTLCOutput{
+                               htlc_id: 5,
+                               amount_msat: 5000000,
+                               cltv_expiry: 505,
+                               payment_hash: PaymentHash([0; 32]),
+                               state: OutboundHTLCState::Committed,
+                               source: HTLCSource::dummy(),
+                       };
+                       out.payment_hash.0 = Sha256::hash(&hex::decode("0505050505050505050505050505050505050505050505050505050505050505").unwrap()).into_inner();
+                       out
+               });
+
+               test_commitment!("30440220048705bec5288d28b3f29344b8d124853b1af423a568664d2c6f02c8ea886525022060f998a461052a2476b912db426ea2a06700953a241135c7957f2e79bc222df9",
+                                "3045022100c4f1d60b6fca9febc8b39de1a31e84c5f7c4b41c97239ef05f4350aa484c6b5e02200c5134ac8b20eb7a29d0dd4a501f6aa8fefb8489171f4cb408bd2a32324ab03f",
+                                "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", {
+
+                                 { 0,
+                                 "304502210081cbb94121761d34c189cd4e6a281feea6f585060ad0ba2632e8d6b3c6bb8a6c02201007981bbd16539d63df2805b5568f1f5688cd2a885d04706f50db9b77ba13c6",
+                                 "304502210090ed76aeb21b53236a598968abc66e2024691d07b62f53ddbeca8f93144af9c602205f873af5a0c10e62690e9aba09740550f194a9dc455ba4c1c23f6cde7704674c",
+                                 "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" },
+                                 { 1,
+                                 "304402201d0f09d2bf7bc245a4f17980e1e9164290df16c70c6a2ff1592f5030d6108581022061e744a7dc151b36bf0aff7a4f1812ba90b8b03633bb979a270d19858fd960c5",
+                                 "30450221009aef000d2e843a4202c1b1a2bf554abc9a7902bf49b2cb0759bc507456b7ebad02204e7c3d193ede2fd2b4cd6b39f51a920e581e35575e357e44d7b699c40ce61d39",
+                                 "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" },
+                                 { 2,
+                                 "30440220010bf035d5823596e50dce2076a4d9f942d8d28031c9c428b901a02b6b8140de02203250e8e4a08bc5b4ecdca4d0eedf98223e02e3ac1c0206b3a7ffdb374aa21e5f",
+                                 "30440220073de0067b88e425b3018b30366bfeda0ccb703118ccd3d02ead08c0f53511d002203fac50ac0e4cf8a3af0b4b1b12e801650591f748f8ddf1e089c160f10b69e511",
+                                 "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" }
+               } );
        }
 
        #[test]