X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Fchannel.rs;h=9d4ccac896cd764b4c9965916014e2e5313200c7;hb=6df9129ace609bfb5c7f08ae0f41175126d05b1b;hp=c95d6e73fe25227e2062f8c865b2a5db61583618;hpb=1d37f56f8a9de6120198e723e5a2daaefcbcaf20;p=rust-lightning

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index c95d6e73..9d4ccac8 100644
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -1,3 +1,12 @@
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
 use bitcoin::blockdata::block::BlockHeader;
 use bitcoin::blockdata::script::{Script,Builder};
 use bitcoin::blockdata::transaction::{TxIn, TxOut, Transaction, SigHashType};
@@ -19,7 +28,7 @@ use ln::msgs;
 use ln::msgs::{DecodeError, OptionalField, DataLossProtect};
 use ln::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, HTLC_FAIL_BACK_BUFFER};
 use ln::channelmanager::{PendingHTLCStatus, HTLCSource, HTLCFailReason, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, PaymentPreimage, PaymentHash, BREAKDOWN_TIMEOUT, MAX_LOCAL_BREAKDOWN_TIMEOUT};
-use ln::chan_utils::{CounterpartyCommitmentSecrets, LocalCommitmentTransaction, TxCreationKeys, HTLCOutputInCommitment, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT, make_funding_redeemscript, ChannelPublicKeys};
+use ln::chan_utils::{CounterpartyCommitmentSecrets, LocalCommitmentTransaction, TxCreationKeys, HTLCOutputInCommitment, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT, make_funding_redeemscript, ChannelPublicKeys, PreCalculatedTxCreationKeys};
 use ln::chan_utils;
 use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
 use chain::transaction::OutPoint;
@@ -34,6 +43,7 @@ use std;
 use std::default::Default;
 use std::{cmp,mem,fmt};
 use std::ops::Deref;
+use bitcoin::hashes::hex::ToHex;
 
 #[cfg(test)]
 pub struct ChannelValueStat {
@@ -376,9 +386,6 @@ pub(super) struct Channel<ChanSigner: ChannelKeys> {
 
 	their_shutdown_scriptpubkey: Option<Script>,
 
-	/// Used exclusively to broadcast the latest local state, mostly a historical quirk that this
-	/// is here:
-	channel_monitor: Option<ChannelMonitor<ChanSigner>>,
 	commitment_secrets: CounterpartyCommitmentSecrets,
 
 	network_sync: UpdateStatus,
@@ -409,17 +416,17 @@ pub const MAX_FUNDING_SATOSHIS: u64 = 1 << 24;
 /// msgs::ErrorAction::SendErrorMessage or msgs::ErrorAction::IgnoreError as appropriate with our
 /// channel_id in ChannelManager.
 pub(super) enum ChannelError {
-	Ignore(&'static str),
-	Close(&'static str),
-	CloseDelayBroadcast(&'static str),
+	Ignore(String),
+	Close(String),
+	CloseDelayBroadcast(String),
 }
 
 impl fmt::Debug for ChannelError {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 		match self {
-			&ChannelError::Ignore(e) => write!(f, "Ignore : {}", e),
-			&ChannelError::Close(e) => write!(f, "Close : {}", e),
-			&ChannelError::CloseDelayBroadcast(e) => write!(f, "CloseDelayBroadcast : {}", e)
+			&ChannelError::Ignore(ref e) => write!(f, "Ignore : {}", e),
+			&ChannelError::Close(ref e) => write!(f, "Close : {}", e),
+			&ChannelError::CloseDelayBroadcast(ref e) => write!(f, "CloseDelayBroadcast : {}", e)
 		}
 	}
 }
@@ -457,20 +464,19 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 	where K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
 	      F::Target: FeeEstimator,
 	{
+		let our_to_self_delay = config.own_channel_config.our_to_self_delay;
 		let chan_keys = keys_provider.get_channel_keys(false, channel_value_satoshis);
 
 		if channel_value_satoshis >= MAX_FUNDING_SATOSHIS {
-			return Err(APIError::APIMisuseError{err: "funding value > 2^24"});
+			return Err(APIError::APIMisuseError{err: format!("funding_value must be smaller than {}, it was {}", MAX_FUNDING_SATOSHIS, channel_value_satoshis)});
 		}
-
-		if push_msat > channel_value_satoshis * 1000 {
-			return Err(APIError::APIMisuseError{err: "push value > channel value"});
+		let channel_value_msat = channel_value_satoshis * 1000;
+		if push_msat > channel_value_msat {
+			return Err(APIError::APIMisuseError { err: format!("Push value ({}) was larger than channel_value ({})", push_msat, channel_value_msat) });
 		}
-		if config.own_channel_config.our_to_self_delay < BREAKDOWN_TIMEOUT {
-			return Err(APIError::APIMisuseError{err: "Configured with an unreasonable our_to_self_delay putting user funds at risks"});
+		if our_to_self_delay < BREAKDOWN_TIMEOUT {
+			return Err(APIError::APIMisuseError {err: format!("Configured with an unreasonable our_to_self_delay ({}) putting user funds at risks", our_to_self_delay)});
 		}
-
-
 		let background_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
 		if Channel::<ChanSigner>::get_remote_channel_reserve_satoshis(channel_value_satoshis) < Channel::<ChanSigner>::derive_our_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});
@@ -536,7 +542,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			their_htlc_minimum_msat: 0,
 			our_htlc_minimum_msat: if config.own_channel_config.our_htlc_minimum_msat == 0 { 1 } else { config.own_channel_config.our_htlc_minimum_msat },
 			their_to_self_delay: 0,
-			our_to_self_delay: config.own_channel_config.our_to_self_delay,
+			our_to_self_delay,
 			their_max_accepted_htlcs: 0,
 			minimum_depth: 0, // Filled in in accept_channel
 
@@ -548,7 +554,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 			their_shutdown_scriptpubkey: None,
 
-			channel_monitor: None,
 			commitment_secrets: CounterpartyCommitmentSecrets::new(),
 
 			network_sync: UpdateStatus::Fresh,
@@ -558,11 +563,13 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 	fn check_remote_fee<F: Deref>(fee_estimator: &F, feerate_per_kw: u32) -> Result<(), ChannelError>
 		where F::Target: FeeEstimator
 	{
-		if feerate_per_kw < fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background) {
-			return Err(ChannelError::Close("Peer's feerate much too low"));
+		let lower_limit = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
+		if feerate_per_kw < lower_limit {
+			return Err(ChannelError::Close(format!("Peer's feerate much too low. Actual: {}. Our expected lower limit: {}", feerate_per_kw, lower_limit)));
 		}
-		if feerate_per_kw as u64 > fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) as u64  * 2 {
-			return Err(ChannelError::Close("Peer's feerate much too high"));
+		let upper_limit = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) as u64  * 2;
+		if feerate_per_kw as u64 > upper_limit {
+			return Err(ChannelError::Close(format!("Peer's feerate much too high. Actual: {}. Our expected upper limit: {}", feerate_per_kw, upper_limit)));
 		}
 		Ok(())
 	}
@@ -581,65 +588,68 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			delayed_payment_basepoint: msg.delayed_payment_basepoint,
 			htlc_basepoint: msg.htlc_basepoint
 		};
-		chan_keys.set_remote_channel_pubkeys(&their_pubkeys);
+		chan_keys.on_accept(&their_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 {
-			return Err(ChannelError::Close("Configured with an unreasonable our_to_self_delay putting user funds at risks"));
+			return Err(ChannelError::Close(format!("Configured with an unreasonable our_to_self_delay ({}) putting user funds at risks. It must be greater than {}", config.own_channel_config.our_to_self_delay, BREAKDOWN_TIMEOUT)));
 		}
 
 		// Check sanity of message fields:
 		if msg.funding_satoshis >= MAX_FUNDING_SATOSHIS {
-			return Err(ChannelError::Close("funding value > 2^24"));
+			return Err(ChannelError::Close(format!("Funding must be smaller than {}. It was {}", MAX_FUNDING_SATOSHIS, msg.funding_satoshis)));
 		}
 		if msg.channel_reserve_satoshis > msg.funding_satoshis {
-			return Err(ChannelError::Close("Bogus channel_reserve_satoshis"));
+			return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must be not greater than funding_satoshis: {}", msg.channel_reserve_satoshis, msg.funding_satoshis)));
 		}
-		if msg.push_msat > (msg.funding_satoshis - msg.channel_reserve_satoshis) * 1000 {
-			return Err(ChannelError::Close("push_msat larger than funding value"));
+		let funding_value = (msg.funding_satoshis - msg.channel_reserve_satoshis) * 1000;
+		if msg.push_msat > funding_value {
+			return Err(ChannelError::Close(format!("push_msat {} was larger than funding value {}", msg.push_msat, funding_value)));
 		}
 		if msg.dust_limit_satoshis > msg.funding_satoshis {
-			return Err(ChannelError::Close("Peer never wants payout outputs?"));
+			return Err(ChannelError::Close(format!("dust_limit_satoshis {} was larger than funding_satoshis {}. Peer never wants payout outputs?", msg.dust_limit_satoshis, msg.funding_satoshis)));
 		}
 		if msg.dust_limit_satoshis > msg.channel_reserve_satoshis {
-			return Err(ChannelError::Close("Bogus; channel reserve is less than dust limit"));
+			return Err(ChannelError::Close(format!("Bogus; channel reserve ({}) is less than dust limit ({})", msg.channel_reserve_satoshis, msg.dust_limit_satoshis)));
 		}
-		if msg.htlc_minimum_msat >= (msg.funding_satoshis - msg.channel_reserve_satoshis) * 1000 {
-			return Err(ChannelError::Close("Minimum htlc value is full channel value"));
+		let full_channel_value_msat = (msg.funding_satoshis - msg.channel_reserve_satoshis) * 1000;
+		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)?;
 
-		if msg.to_self_delay > config.peer_channel_config_limits.their_to_self_delay || msg.to_self_delay > MAX_LOCAL_BREAKDOWN_TIMEOUT {
-			return Err(ChannelError::Close("They wanted our payments to be delayed by a needlessly long period"));
+		let max_to_self_delay = u16::min(config.peer_channel_config_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
+		if msg.to_self_delay > max_to_self_delay {
+			return Err(ChannelError::Close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_to_self_delay, msg.to_self_delay)));
 		}
 		if msg.max_accepted_htlcs < 1 {
-			return Err(ChannelError::Close("0 max_accpted_htlcs makes for a useless channel"));
+			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("max_accpted_htlcs > 483"));
+			return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than 483", msg.max_accepted_htlcs)));
 		}
 
 		// Now check against optional parameters as set by config...
 		if msg.funding_satoshis < config.peer_channel_config_limits.min_funding_satoshis {
-			return Err(ChannelError::Close("funding satoshis is less than the user specified limit"));
+			return Err(ChannelError::Close(format!("Funding satoshis ({}) is less than the user specified limit ({})", msg.funding_satoshis, config.peer_channel_config_limits.min_funding_satoshis)));
 		}
 		if msg.htlc_minimum_msat > config.peer_channel_config_limits.max_htlc_minimum_msat {
-			return Err(ChannelError::Close("htlc minimum msat is higher than the user specified limit"));
+			return Err(ChannelError::Close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", msg.htlc_minimum_msat,  config.peer_channel_config_limits.max_htlc_minimum_msat)));
 		}
 		if msg.max_htlc_value_in_flight_msat < config.peer_channel_config_limits.min_max_htlc_value_in_flight_msat {
-			return Err(ChannelError::Close("max htlc value in flight msat is less than the user specified limit"));
+			return Err(ChannelError::Close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", msg.max_htlc_value_in_flight_msat, config.peer_channel_config_limits.min_max_htlc_value_in_flight_msat)));
 		}
 		if msg.channel_reserve_satoshis > config.peer_channel_config_limits.max_channel_reserve_satoshis {
-			return Err(ChannelError::Close("channel reserve satoshis is higher than the user specified limit"));
+			return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", msg.channel_reserve_satoshis, config.peer_channel_config_limits.max_channel_reserve_satoshis)));
 		}
 		if msg.max_accepted_htlcs < config.peer_channel_config_limits.min_max_accepted_htlcs {
-			return Err(ChannelError::Close("max accepted htlcs is less than the user specified limit"));
+			return Err(ChannelError::Close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", msg.max_accepted_htlcs, config.peer_channel_config_limits.min_max_accepted_htlcs)));
 		}
 		if msg.dust_limit_satoshis < config.peer_channel_config_limits.min_dust_limit_satoshis {
-			return Err(ChannelError::Close("dust limit satoshis is less than the user specified limit"));
+			return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is less than the user specified limit ({})", msg.dust_limit_satoshis, config.peer_channel_config_limits.min_dust_limit_satoshis)));
 		}
 		if msg.dust_limit_satoshis > config.peer_channel_config_limits.max_dust_limit_satoshis {
-			return Err(ChannelError::Close("dust limit satoshis is greater than the user specified limit"));
+			return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is greater than the user specified limit ({})", msg.dust_limit_satoshis, config.peer_channel_config_limits.max_dust_limit_satoshis)));
 		}
 
 		// Convert things into internal flags and prep our state:
@@ -647,7 +657,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		let their_announce = if (msg.channel_flags & 1) == 1 { true } else { false };
 		if config.peer_channel_config_limits.force_announced_channel_preference {
 			if local_config.announced_channel != their_announce {
-				return Err(ChannelError::Close("Peer tried to open channel but their announcement preference is different from ours"));
+				return Err(ChannelError::Close("Peer tried to open channel but their announcement preference is different from ours".to_owned()));
 			}
 		}
 		// we either accept their preference or the preferences match
@@ -658,26 +668,27 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		let our_dust_limit_satoshis = Channel::<ChanSigner>::derive_our_dust_limit_satoshis(background_feerate);
 		let remote_channel_reserve_satoshis = Channel::<ChanSigner>::get_remote_channel_reserve_satoshis(msg.funding_satoshis);
 		if remote_channel_reserve_satoshis < our_dust_limit_satoshis {
-			return Err(ChannelError::Close("Suitable channel reserve not found. aborting"));
+			return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({}). our_dust_limit_satoshis is ({}).", remote_channel_reserve_satoshis, our_dust_limit_satoshis)));
 		}
 		if msg.channel_reserve_satoshis < our_dust_limit_satoshis {
-			return Err(ChannelError::Close("channel_reserve_satoshis too small"));
+			return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is smaller than our dust limit ({})", msg.channel_reserve_satoshis, our_dust_limit_satoshis)));
 		}
 		if remote_channel_reserve_satoshis < msg.dust_limit_satoshis {
-			return Err(ChannelError::Close("Dust limit too high for the channel reserve we require the remote to keep"));
+			return Err(ChannelError::Close(format!("Dust limit ({}) too high for the channel reserve we require the remote to keep ({})", msg.dust_limit_satoshis, remote_channel_reserve_satoshis)));
 		}
 
 		// check if the funder's amount for the initial commitment tx is sufficient
 		// for full fee payment
 		let funders_amount_msat = msg.funding_satoshis * 1000 - msg.push_msat;
-		if funders_amount_msat < background_feerate as u64 * COMMITMENT_TX_BASE_WEIGHT {
-			return Err(ChannelError::Close("Insufficient funding amount for initial commitment"));
+		let lower_limit = background_feerate as u64 * COMMITMENT_TX_BASE_WEIGHT;
+		if funders_amount_msat < lower_limit {
+			return Err(ChannelError::Close(format!("Insufficient funding amount ({}) for initial commitment. Must be at least {}", funders_amount_msat, lower_limit)));
 		}
 
 		let to_local_msat = msg.push_msat;
 		let to_remote_msat = funders_amount_msat - background_feerate as u64 * COMMITMENT_TX_BASE_WEIGHT;
 		if to_local_msat <= msg.channel_reserve_satoshis * 1000 && to_remote_msat <= remote_channel_reserve_satoshis * 1000 {
-			return Err(ChannelError::Close("Insufficient funding amount for initial commitment"));
+			return Err(ChannelError::Close("Insufficient funding amount for initial commitment".to_owned()));
 		}
 
 		let their_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
@@ -691,12 +702,12 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 						None
 					// Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. Fail the channel
 					} else {
-						return Err(ChannelError::Close("Peer is signaling upfront_shutdown but has provided a non-accepted scriptpubkey format"));
+						return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided a non-accepted scriptpubkey format. script: ({})", script.to_bytes().to_hex())));
 					}
 				},
 				// 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
 				&OptionalField::Absent => {
-					return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out"));
+					return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
 				}
 			}
 		} else { None };
@@ -771,7 +782,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 			their_shutdown_scriptpubkey,
 
-			channel_monitor: None,
 			commitment_secrets: CounterpartyCommitmentSecrets::new(),
 
 			network_sync: UpdateStatus::Fresh,
@@ -780,13 +790,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		Ok(chan)
 	}
 
-	// Utilities to derive keys:
-
-	fn build_local_commitment_secret(&self, idx: u64) -> SecretKey {
-		let res = self.local_keys.commitment_secret(idx);
-		SecretKey::from_slice(&res).unwrap()
-	}
-
 	// Utilities to build transactions:
 
 	fn get_commitment_transaction_number_obscure_factor(&self) -> u64 {
@@ -1118,12 +1121,12 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 	/// The result is a transaction which we can revoke ownership of (ie a "local" transaction)
 	/// TODO Some magic rust shit to compile-time check this?
 	fn build_local_transaction_keys(&self, commitment_number: u64) -> Result<TxCreationKeys, ChannelError> {
-		let per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &self.build_local_commitment_secret(commitment_number));
+		let per_commitment_point = self.local_keys.get_per_commitment_point(commitment_number, &self.secp_ctx);
 		let delayed_payment_base = &self.local_keys.pubkeys().delayed_payment_basepoint;
 		let htlc_basepoint = &self.local_keys.pubkeys().htlc_basepoint;
 		let their_pubkeys = self.their_pubkeys.as_ref().unwrap();
 
-		Ok(secp_check!(TxCreationKeys::new(&self.secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &their_pubkeys.revocation_basepoint, &their_pubkeys.htlc_basepoint), "Local tx keys generation got bogus keys"))
+		Ok(secp_check!(TxCreationKeys::new(&self.secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &their_pubkeys.revocation_basepoint, &their_pubkeys.htlc_basepoint), "Local tx keys generation got bogus keys".to_owned()))
 	}
 
 	#[inline]
@@ -1137,7 +1140,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		let htlc_basepoint = &self.local_keys.pubkeys().htlc_basepoint;
 		let their_pubkeys = self.their_pubkeys.as_ref().unwrap();
 
-		Ok(secp_check!(TxCreationKeys::new(&self.secp_ctx, &self.their_cur_commitment_point.unwrap(), &their_pubkeys.delayed_payment_basepoint, &their_pubkeys.htlc_basepoint, revocation_basepoint, htlc_basepoint), "Remote tx keys generation got bogus keys"))
+		Ok(secp_check!(TxCreationKeys::new(&self.secp_ctx, &self.their_cur_commitment_point.unwrap(), &their_pubkeys.delayed_payment_basepoint, &their_pubkeys.htlc_basepoint, revocation_basepoint, htlc_basepoint), "Remote tx keys generation got bogus keys".to_owned()))
 	}
 
 	/// Gets the redeemscript for the funding transaction output (ie the funding transaction output
@@ -1200,7 +1203,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			}
 		}
 		if pending_idx == std::usize::MAX {
-			return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID"));
+			return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID".to_owned()));
 		}
 
 		// Now update local state:
@@ -1214,7 +1217,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				payment_preimage: payment_preimage_arg.clone(),
 			}],
 		};
-		self.channel_monitor.as_mut().unwrap().update_monitor_ooo(monitor_update.clone(), logger).unwrap();
 
 		if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32)) != 0 {
 			for pending_update in self.holding_cell_htlc_updates.iter() {
@@ -1310,14 +1312,14 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 					},
 					_ => {
 						debug_assert!(false, "Have an inbound HTLC we tried to claim before it was fully committed to");
-						return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID"));
+						return Err(ChannelError::Ignore(format!("Unable to find a pending HTLC which matched the given HTLC ID ({})", htlc.htlc_id)));
 					}
 				}
 				pending_idx = idx;
 			}
 		}
 		if pending_idx == std::usize::MAX {
-			return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID"));
+			return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID".to_owned()));
 		}
 
 		// Now update local state:
@@ -1327,13 +1329,13 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 					&HTLCUpdateAwaitingACK::ClaimHTLC { htlc_id, .. } => {
 						if htlc_id_arg == htlc_id {
 							debug_assert!(false, "Tried to fail an HTLC that was already fulfilled");
-							return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID"));
+							return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID".to_owned()));
 						}
 					},
 					&HTLCUpdateAwaitingACK::FailHTLC { htlc_id, .. } => {
 						if htlc_id_arg == htlc_id {
 							debug_assert!(false, "Tried to fail an HTLC that was already failed");
-							return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID"));
+							return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID".to_owned()));
 						}
 					},
 					_ => {}
@@ -1363,60 +1365,63 @@ 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 {
-			return Err(ChannelError::Close("Got an accept_channel message from an inbound peer"));
+			return Err(ChannelError::Close("Got an accept_channel message from an inbound peer".to_owned()));
 		}
 		if self.channel_state != ChannelState::OurInitSent as u32 {
-			return Err(ChannelError::Close("Got an accept_channel message at a strange time"));
+			return Err(ChannelError::Close("Got an accept_channel message at a strange time".to_owned()));
 		}
 		if msg.dust_limit_satoshis > 21000000 * 100000000 {
-			return Err(ChannelError::Close("Peer never wants payout outputs?"));
+			return Err(ChannelError::Close(format!("Peer never wants payout outputs? dust_limit_satoshis was {}", msg.dust_limit_satoshis)));
 		}
 		if msg.channel_reserve_satoshis > self.channel_value_satoshis {
-			return Err(ChannelError::Close("Bogus channel_reserve_satoshis"));
+			return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than ({})", msg.channel_reserve_satoshis, self.channel_value_satoshis)));
 		}
 		if msg.dust_limit_satoshis > msg.channel_reserve_satoshis {
-			return Err(ChannelError::Close("Bogus channel_reserve and dust_limit"));
+			return Err(ChannelError::Close(format!("Bogus channel_reserve ({}) and dust_limit ({})", msg.channel_reserve_satoshis, msg.dust_limit_satoshis)));
 		}
 		if msg.channel_reserve_satoshis < self.our_dust_limit_satoshis {
-			return Err(ChannelError::Close("Peer never wants payout outputs?"));
+			return Err(ChannelError::Close(format!("Peer never wants payout outputs? channel_reserve_satoshis was ({}). our_dust_limit is ({})", msg.channel_reserve_satoshis, self.our_dust_limit_satoshis)));
 		}
-		if msg.dust_limit_satoshis > Channel::<ChanSigner>::get_remote_channel_reserve_satoshis(self.channel_value_satoshis) {
-			return Err(ChannelError::Close("Dust limit is bigger than our channel reverse"));
+		let remote_reserve = Channel::<ChanSigner>::get_remote_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)));
 		}
-		if msg.htlc_minimum_msat >= (self.channel_value_satoshis - msg.channel_reserve_satoshis) * 1000 {
-			return Err(ChannelError::Close("Minimum htlc value is full channel value"));
+		let full_channel_value_msat = (self.channel_value_satoshis - msg.channel_reserve_satoshis) * 1000;
+		if msg.htlc_minimum_msat >= full_channel_value_msat {
+			return Err(ChannelError::Close(format!("Minimum htlc value ({}) is full channel value ({})", msg.htlc_minimum_msat, full_channel_value_msat)));
 		}
-		if msg.to_self_delay > config.peer_channel_config_limits.their_to_self_delay || msg.to_self_delay > MAX_LOCAL_BREAKDOWN_TIMEOUT {
-			return Err(ChannelError::Close("They wanted our payments to be delayed by a needlessly long period"));
+		let max_delay_acceptable = u16::min(config.peer_channel_config_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
+		if msg.to_self_delay > max_delay_acceptable {
+			return Err(ChannelError::Close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_delay_acceptable, msg.to_self_delay)));
 		}
 		if msg.max_accepted_htlcs < 1 {
-			return Err(ChannelError::Close("0 max_accepted_htlcs makes for a useless channel"));
+			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("max_accepted_htlcs > 483"));
+			return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than 483", msg.max_accepted_htlcs)));
 		}
 
 		// Now check against optional parameters as set by config...
 		if msg.htlc_minimum_msat > config.peer_channel_config_limits.max_htlc_minimum_msat {
-			return Err(ChannelError::Close("htlc minimum msat is higher than the user specified limit"));
+			return Err(ChannelError::Close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", msg.htlc_minimum_msat, config.peer_channel_config_limits.max_htlc_minimum_msat)));
 		}
 		if msg.max_htlc_value_in_flight_msat < config.peer_channel_config_limits.min_max_htlc_value_in_flight_msat {
-			return Err(ChannelError::Close("max htlc value in flight msat is less than the user specified limit"));
+			return Err(ChannelError::Close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", msg.max_htlc_value_in_flight_msat, config.peer_channel_config_limits.min_max_htlc_value_in_flight_msat)));
 		}
 		if msg.channel_reserve_satoshis > config.peer_channel_config_limits.max_channel_reserve_satoshis {
-			return Err(ChannelError::Close("channel reserve satoshis is higher than the user specified limit"));
+			return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", msg.channel_reserve_satoshis, config.peer_channel_config_limits.max_channel_reserve_satoshis)));
 		}
 		if msg.max_accepted_htlcs < config.peer_channel_config_limits.min_max_accepted_htlcs {
-			return Err(ChannelError::Close("max accepted htlcs is less than the user specified limit"));
+			return Err(ChannelError::Close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", msg.max_accepted_htlcs, config.peer_channel_config_limits.min_max_accepted_htlcs)));
 		}
 		if msg.dust_limit_satoshis < config.peer_channel_config_limits.min_dust_limit_satoshis {
-			return Err(ChannelError::Close("dust limit satoshis is less than the user specified limit"));
+			return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is less than the user specified limit ({})", msg.dust_limit_satoshis, config.peer_channel_config_limits.min_dust_limit_satoshis)));
 		}
 		if msg.dust_limit_satoshis > config.peer_channel_config_limits.max_dust_limit_satoshis {
-			return Err(ChannelError::Close("dust limit satoshis is greater than the user specified limit"));
+			return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is greater than the user specified limit ({})", msg.dust_limit_satoshis, config.peer_channel_config_limits.max_dust_limit_satoshis)));
 		}
 		if msg.minimum_depth > config.peer_channel_config_limits.max_minimum_depth {
-			return Err(ChannelError::Close("We consider the minimum depth to be unreasonably large"));
+			return Err(ChannelError::Close(format!("We consider the minimum depth to be unreasonably large. Expected minimum: ({}). Actual: ({})", config.peer_channel_config_limits.max_minimum_depth, msg.minimum_depth)));
 		}
 
 		let their_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
@@ -1430,12 +1435,12 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 						None
 					// Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. Fail the channel
 					} else {
-						return Err(ChannelError::Close("Peer is signaling upfront_shutdown but has provided a non-accepted scriptpubkey format"));
+						return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided a non-accepted scriptpubkey format. scriptpubkey: ({})", script.to_bytes().to_hex())));
 					}
 				},
 				// 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
 				&OptionalField::Absent => {
-					return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out"));
+					return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
 				}
 			}
 		} else { None };
@@ -1456,7 +1461,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			htlc_basepoint: msg.htlc_basepoint
 		};
 
-		self.local_keys.set_remote_channel_pubkeys(&their_pubkeys);
+		self.local_keys.on_accept(&their_pubkeys, msg.to_self_delay, self.our_to_self_delay);
 		self.their_pubkeys = Some(their_pubkeys);
 
 		self.their_cur_commitment_point = Some(msg.first_per_commitment_point);
@@ -1476,14 +1481,15 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 		// They sign the "local" 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.their_funding_pubkey().serialize()), encode::serialize_hex(&local_initial_commitment_tx), log_bytes!(local_sighash[..]), encode::serialize_hex(&funding_script));
-		secp_check!(self.secp_ctx.verify(&local_sighash, &sig, self.their_funding_pubkey()), "Invalid funding_created signature from peer");
+		secp_check!(self.secp_ctx.verify(&local_sighash, &sig, self.their_funding_pubkey()), "Invalid funding_created signature from peer".to_owned());
 
 		let localtx = LocalCommitmentTransaction::new_missing_local_sig(local_initial_commitment_tx, sig.clone(), &self.local_keys.pubkeys().funding_pubkey, self.their_funding_pubkey(), local_keys, self.feerate_per_kw, Vec::new());
 
 		let remote_keys = self.build_remote_transaction_keys()?;
 		let remote_initial_commitment_tx = self.build_commitment_transaction(self.cur_remote_commitment_transaction_number, &remote_keys, false, false, self.feerate_per_kw, logger).0;
-		let remote_signature = self.local_keys.sign_remote_commitment(self.feerate_per_kw, &remote_initial_commitment_tx, &remote_keys, &Vec::new(), self.our_to_self_delay, &self.secp_ctx)
-				.map_err(|_| ChannelError::Close("Failed to get signatures for new commitment_signed"))?.0;
+		let pre_remote_keys = PreCalculatedTxCreationKeys::new(remote_keys);
+		let remote_signature = self.local_keys.sign_remote_commitment(self.feerate_per_kw, &remote_initial_commitment_tx, &pre_remote_keys, &Vec::new(), &self.secp_ctx)
+				.map_err(|_| ChannelError::Close("Failed to get signatures for new commitment_signed".to_owned()))?.0;
 
 		// We sign the "remote" commitment transaction, allowing them to broadcast the tx if they wish.
 		Ok((remote_initial_commitment_tx, localtx, remote_signature))
@@ -1495,13 +1501,13 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 	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 {
-			return Err(ChannelError::Close("Received funding_created for an outbound channel?"));
+			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) {
 			// BOLT 2 says that if we disconnect before we send funding_signed we SHOULD NOT
 			// remember the channel, so it's safe to just send an error_message here and drop the
 			// channel.
-			return Err(ChannelError::Close("Received funding_created after we got the channel!"));
+			return Err(ChannelError::Close("Received funding_created after we got the channel!".to_owned()));
 		}
 		if self.commitment_secrets.get_min_seen_secret() != (1 << 48) ||
 				self.cur_remote_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER ||
@@ -1540,7 +1546,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			} }
 		}
 
-		self.channel_monitor = Some(create_monitor!());
 		let channel_monitor = create_monitor!();
 
 		self.channel_state = ChannelState::FundingSent as u32;
@@ -1558,10 +1563,10 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 	/// 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 {
-			return Err(ChannelError::Close("Received funding_signed for an inbound channel?"));
+			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 {
-			return Err(ChannelError::Close("Received funding_signed in strange state!"));
+			return Err(ChannelError::Close("Received funding_signed in strange state!".to_owned()));
 		}
 		if self.commitment_secrets.get_min_seen_secret() != (1 << 48) ||
 				self.cur_remote_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER ||
@@ -1582,7 +1587,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 		// They sign the "local" commitment transaction, allowing us to broadcast the tx if we wish.
 		if let Err(_) = self.secp_ctx.verify(&local_sighash, &msg.signature, their_funding_pubkey) {
-			return Err(ChannelError::Close("Invalid funding_signed signature from peer"));
+			return Err(ChannelError::Close("Invalid funding_signed signature from peer".to_owned()));
 		}
 
 		let their_pubkeys = self.their_pubkeys.as_ref().unwrap();
@@ -1606,7 +1611,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			} }
 		}
 
-		self.channel_monitor = Some(create_monitor!());
 		let channel_monitor = create_monitor!();
 
 		assert_eq!(self.channel_state & (ChannelState::MonitorUpdateFailed as u32), 0); // We have no had any monitor(s) yet to fail update!
@@ -1619,7 +1623,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 	pub fn funding_locked(&mut self, msg: &msgs::FundingLocked) -> Result<(), ChannelError> {
 		if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-			return Err(ChannelError::Close("Peer sent funding_locked when we needed a channel_reestablish"));
+			return Err(ChannelError::Close("Peer sent funding_locked when we needed a channel_reestablish".to_owned()));
 		}
 
 		let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS);
@@ -1637,12 +1641,12 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				(self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::TheirFundingLocked as u32) ==
 				                      (ChannelState::FundingSent as u32 | ChannelState::TheirFundingLocked as u32)) {
 			if self.their_cur_commitment_point != Some(msg.next_per_commitment_point) {
-				return Err(ChannelError::Close("Peer sent a reconnect funding_locked with a different point"));
+				return Err(ChannelError::Close("Peer sent a reconnect funding_locked with a different point".to_owned()));
 			}
 			// They probably disconnected/reconnected and re-sent the funding_locked, which is required
 			return Ok(());
 		} else {
-			return Err(ChannelError::Close("Peer sent a funding_locked at a strange time"));
+			return Err(ChannelError::Close("Peer sent a funding_locked at a strange time".to_owned()));
 		}
 
 		self.their_prev_commitment_point = self.their_cur_commitment_point;
@@ -1684,8 +1688,8 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 	/// corner case properly.
 	pub fn get_inbound_outbound_available_balance_msat(&self) -> (u64, u64) {
 		// Note that we have to handle overflow due to the above case.
-		(cmp::min(self.channel_value_satoshis as i64 * 1000 - self.value_to_self_msat as i64 - self.get_inbound_pending_htlc_stats().1 as i64, 0) as u64,
-		cmp::min(self.value_to_self_msat as i64 - self.get_outbound_pending_htlc_stats().1 as i64, 0) as u64)
+		(cmp::max(self.channel_value_satoshis as i64 * 1000 - self.value_to_self_msat as i64 - self.get_inbound_pending_htlc_stats().1 as i64, 0) as u64,
+		cmp::max(self.value_to_self_msat as i64 - self.get_outbound_pending_htlc_stats().1 as i64, 0) as u64)
 	}
 
 	// Get the fee cost of a commitment tx with a given number of HTLC outputs.
@@ -1765,28 +1769,28 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		// If the remote has sent a shutdown prior to adding this HTLC, then they are in violation of the spec.
 		let remote_sent_shutdown = (self.channel_state & (ChannelState::ChannelFunded as u32 | ChannelState::RemoteShutdownSent as u32)) != (ChannelState::ChannelFunded as u32);
 		if remote_sent_shutdown {
-			return Err(ChannelError::Close("Got add HTLC message when channel was not in an operational state"));
+			return Err(ChannelError::Close("Got add HTLC message when channel was not in an operational state".to_owned()));
 		}
 		if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-			return Err(ChannelError::Close("Peer sent update_add_htlc when we needed a channel_reestablish"));
+			return Err(ChannelError::Close("Peer sent update_add_htlc when we needed a channel_reestablish".to_owned()));
 		}
 		if msg.amount_msat > self.channel_value_satoshis * 1000 {
-			return Err(ChannelError::Close("Remote side tried to send more than the total value of the channel"));
+			return Err(ChannelError::Close("Remote side tried to send more than the total value of the channel".to_owned()));
 		}
 		if msg.amount_msat == 0 {
-			return Err(ChannelError::Close("Remote side tried to send a 0-msat HTLC"));
+			return Err(ChannelError::Close("Remote side tried to send a 0-msat HTLC".to_owned()));
 		}
 		if msg.amount_msat < self.our_htlc_minimum_msat {
-			return Err(ChannelError::Close("Remote side tried to send less than our minimum HTLC value"));
+			return Err(ChannelError::Close(format!("Remote side tried to send less than our minimum HTLC value. Lower limit: ({}). Actual: ({})", self.our_htlc_minimum_msat, msg.amount_msat)));
 		}
 
 		let (inbound_htlc_count, htlc_inbound_value_msat) = self.get_inbound_pending_htlc_stats();
 		if inbound_htlc_count + 1 > OUR_MAX_HTLCS as u32 {
-			return Err(ChannelError::Close("Remote tried to push more than our max accepted HTLCs"));
+			return Err(ChannelError::Close(format!("Remote tried to push more than our max accepted HTLCs ({})", OUR_MAX_HTLCS)));
 		}
-		// Check our_max_htlc_value_in_flight_msat
-		if htlc_inbound_value_msat + msg.amount_msat > Channel::<ChanSigner>::get_our_max_htlc_value_in_flight_msat(self.channel_value_satoshis) {
-			return Err(ChannelError::Close("Remote HTLC add would put them over our max HTLC value"));
+		let our_max_htlc_value_in_flight_msat = Channel::<ChanSigner>::get_our_max_htlc_value_in_flight_msat(self.channel_value_satoshis);
+		if htlc_inbound_value_msat + msg.amount_msat > our_max_htlc_value_in_flight_msat {
+			return Err(ChannelError::Close(format!("Remote HTLC add would put them over our max HTLC value ({})", our_max_htlc_value_in_flight_msat)));
 		}
 		// Check remote_channel_reserve_satoshis (we're getting paid, so they have to at least meet
 		// the reserve_satoshis we told them to always have as direct payment so that they lose
@@ -1814,7 +1818,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		let pending_remote_value_msat =
 			self.channel_value_satoshis * 1000 - pending_value_to_self_msat;
 		if pending_remote_value_msat < msg.amount_msat {
-			return Err(ChannelError::Close("Remote HTLC add would overdraw remaining funds"));
+			return Err(ChannelError::Close("Remote HTLC add would overdraw remaining funds".to_owned()));
 		}
 
 		// Check that the remote can afford to pay for this HTLC on-chain at the current
@@ -1824,13 +1828,13 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			self.next_remote_commit_tx_fee_msat(1)
 		};
 		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"));
+			return Err(ChannelError::Close("Remote HTLC add would not leave enough to pay for fees".to_owned()));
 		};
 
 		let chan_reserve_msat =
 			Channel::<ChanSigner>::get_remote_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"));
+			return Err(ChannelError::Close("Remote HTLC add would put them under remote reserve value".to_owned()));
 		}
 
 		if !self.channel_outbound {
@@ -1854,15 +1858,15 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			// +1 for this HTLC.
 			let local_commit_tx_fee_msat = self.next_local_commit_tx_fee_msat(1);
 			if self.value_to_self_msat < self.local_channel_reserve_satoshis * 1000 + local_commit_tx_fee_msat {
-				return Err(ChannelError::Close("Cannot receive value that would put us under local channel reserve value"));
+				return Err(ChannelError::Close("Cannot receive value that would put us under local channel reserve value".to_owned()));
 			}
 		}
 
 		if self.next_remote_htlc_id != msg.htlc_id {
-			return Err(ChannelError::Close("Remote skipped HTLC ID"));
+			return Err(ChannelError::Close(format!("Remote skipped HTLC ID (skipped ID: {})", self.next_remote_htlc_id)));
 		}
 		if msg.cltv_expiry >= 500000000 {
-			return Err(ChannelError::Close("Remote provided CLTV expiry in seconds instead of block height"));
+			return Err(ChannelError::Close("Remote provided CLTV expiry in seconds instead of block height".to_owned()));
 		}
 
 		if self.channel_state & ChannelState::LocalShutdownSent as u32 != 0 {
@@ -1892,30 +1896,30 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 					None => {},
 					Some(payment_hash) =>
 						if payment_hash != htlc.payment_hash {
-							return Err(ChannelError::Close("Remote tried to fulfill HTLC with an incorrect preimage"));
+							return Err(ChannelError::Close(format!("Remote tried to fulfill HTLC ({}) with an incorrect preimage", htlc_id)));
 						}
 				};
 				match htlc.state {
 					OutboundHTLCState::LocalAnnounced(_) =>
-						return Err(ChannelError::Close("Remote tried to fulfill/fail HTLC before it had been committed")),
+						return Err(ChannelError::Close(format!("Remote tried to fulfill/fail HTLC ({}) before it had been committed", htlc_id))),
 					OutboundHTLCState::Committed => {
 						htlc.state = OutboundHTLCState::RemoteRemoved(fail_reason);
 					},
 					OutboundHTLCState::AwaitingRemoteRevokeToRemove(_) | OutboundHTLCState::AwaitingRemovedRemoteRevoke(_) | OutboundHTLCState::RemoteRemoved(_) =>
-						return Err(ChannelError::Close("Remote tried to fulfill/fail HTLC that they'd already fulfilled/failed")),
+						return Err(ChannelError::Close(format!("Remote tried to fulfill/fail HTLC ({}) that they'd already fulfilled/failed", htlc_id))),
 				}
 				return Ok(&htlc.source);
 			}
 		}
-		Err(ChannelError::Close("Remote tried to fulfill/fail an HTLC we couldn't find"))
+		Err(ChannelError::Close("Remote tried to fulfill/fail an HTLC we couldn't find".to_owned()))
 	}
 
 	pub fn update_fulfill_htlc(&mut self, msg: &msgs::UpdateFulfillHTLC) -> Result<HTLCSource, ChannelError> {
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-			return Err(ChannelError::Close("Got fulfill HTLC message when channel was not in an operational state"));
+			return Err(ChannelError::Close("Got fulfill HTLC message when channel was not in an operational state".to_owned()));
 		}
 		if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-			return Err(ChannelError::Close("Peer sent update_fulfill_htlc when we needed a channel_reestablish"));
+			return Err(ChannelError::Close("Peer sent update_fulfill_htlc when we needed a channel_reestablish".to_owned()));
 		}
 
 		let payment_hash = PaymentHash(Sha256::hash(&msg.payment_preimage.0[..]).into_inner());
@@ -1924,10 +1928,10 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 	pub fn update_fail_htlc(&mut self, msg: &msgs::UpdateFailHTLC, fail_reason: HTLCFailReason) -> Result<(), ChannelError> {
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-			return Err(ChannelError::Close("Got fail HTLC message when channel was not in an operational state"));
+			return Err(ChannelError::Close("Got fail HTLC message when channel was not in an operational state".to_owned()));
 		}
 		if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-			return Err(ChannelError::Close("Peer sent update_fail_htlc when we needed a channel_reestablish"));
+			return Err(ChannelError::Close("Peer sent update_fail_htlc when we needed a channel_reestablish".to_owned()));
 		}
 
 		self.mark_outbound_htlc_removed(msg.htlc_id, None, Some(fail_reason))?;
@@ -1936,10 +1940,10 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 	pub fn update_fail_malformed_htlc(&mut self, msg: &msgs::UpdateFailMalformedHTLC, fail_reason: HTLCFailReason) -> Result<(), ChannelError> {
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-			return Err(ChannelError::Close("Got fail malformed HTLC message when channel was not in an operational state"));
+			return Err(ChannelError::Close("Got fail malformed HTLC message when channel was not in an operational state".to_owned()));
 		}
 		if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-			return Err(ChannelError::Close("Peer sent update_fail_malformed_htlc when we needed a channel_reestablish"));
+			return Err(ChannelError::Close("Peer sent update_fail_malformed_htlc when we needed a channel_reestablish".to_owned()));
 		}
 
 		self.mark_outbound_htlc_removed(msg.htlc_id, None, Some(fail_reason))?;
@@ -1951,13 +1955,13 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				L::Target: Logger
 	{
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-			return Err((None, ChannelError::Close("Got commitment signed message when channel was not in an operational state")));
+			return Err((None, ChannelError::Close("Got commitment signed message when channel was not in an operational state".to_owned())));
 		}
 		if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-			return Err((None, ChannelError::Close("Peer sent commitment_signed when we needed a channel_reestablish")));
+			return Err((None, ChannelError::Close("Peer sent commitment_signed when we needed a channel_reestablish".to_owned())));
 		}
 		if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK == BOTH_SIDES_SHUTDOWN_MASK && self.last_sent_closing_fee.is_some() {
-			return Err((None, ChannelError::Close("Peer sent commitment_signed after we'd started exchanging closing_signeds")));
+			return Err((None, ChannelError::Close("Peer sent commitment_signed after we'd started exchanging closing_signeds".to_owned())));
 		}
 
 		let funding_script = self.get_funding_redeemscript();
@@ -1981,7 +1985,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		let local_sighash = hash_to_message!(&bip143::SighashComponents::new(&local_commitment_tx.0).sighash_all(&local_commitment_tx.0.input[0], &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.their_funding_pubkey().serialize()), encode::serialize_hex(&local_commitment_tx.0), log_bytes!(local_sighash[..]), encode::serialize_hex(&funding_script));
 		if let Err(_) = self.secp_ctx.verify(&local_sighash, &msg.signature, &self.their_funding_pubkey()) {
-			return Err((None, ChannelError::Close("Invalid commitment tx signature from peer")));
+			return Err((None, ChannelError::Close("Invalid commitment tx signature from peer".to_owned())));
 		}
 
 		//If channel fee was updated by funder confirm funder can afford the new fee rate when applied to the current local commitment transaction
@@ -1991,12 +1995,12 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 			let remote_reserve_we_require = Channel::<ChanSigner>::get_remote_channel_reserve_satoshis(self.channel_value_satoshis);
 			if self.channel_value_satoshis - self.value_to_self_msat / 1000 < total_fee + remote_reserve_we_require {
-				return Err((None, ChannelError::Close("Funding remote cannot afford proposed new fee")));
+				return Err((None, ChannelError::Close("Funding remote cannot afford proposed new fee".to_owned())));
 			}
 		}
 
 		if msg.htlc_signatures.len() != local_commitment_tx.1 {
-			return Err((None, ChannelError::Close("Got wrong number of HTLC signatures from remote")));
+			return Err((None, ChannelError::Close(format!("Got wrong number of HTLC signatures ({}) from remote. It must be {}", msg.htlc_signatures.len(), local_commitment_tx.1))));
 		}
 
 		// TODO: Merge these two, sadly they are currently both required to be passed separately to
@@ -2010,7 +2014,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
 				log_trace!(logger, "Checking HTLC tx signature {} by key {} against tx {} (sighash {}) with redeemscript {}", log_bytes!(msg.htlc_signatures[idx].serialize_compact()[..]), log_bytes!(local_keys.b_htlc_key.serialize()), encode::serialize_hex(&htlc_tx), log_bytes!(htlc_sighash[..]), encode::serialize_hex(&htlc_redeemscript));
 				if let Err(_) = self.secp_ctx.verify(&htlc_sighash, &msg.htlc_signatures[idx], &local_keys.b_htlc_key) {
-					return Err((None, ChannelError::Close("Invalid HTLC tx signature from peer")));
+					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));
@@ -2020,8 +2024,8 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			}
 		}
 
-		let next_per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &self.build_local_commitment_secret(self.cur_local_commitment_transaction_number - 1));
-		let per_commitment_secret = self.local_keys.commitment_secret(self.cur_local_commitment_transaction_number + 1);
+		let next_per_commitment_point = self.local_keys.get_per_commitment_point(self.cur_local_commitment_transaction_number - 1, &self.secp_ctx);
+		let per_commitment_secret = self.local_keys.release_commitment_secret(self.cur_local_commitment_transaction_number + 1);
 
 		// Update state now that we've passed all the can-fail calls...
 		let mut need_our_commitment = false;
@@ -2048,7 +2052,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				htlc_outputs: htlcs_and_sigs
 			}]
 		};
-		self.channel_monitor.as_mut().unwrap().update_monitor_ooo(monitor_update.clone(), logger).unwrap();
 
 		for htlc in self.pending_inbound_htlcs.iter_mut() {
 			let new_forward = if let &InboundHTLCState::RemoteAnnounced(ref forward_info) = &htlc.state {
@@ -2090,7 +2093,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			}
 			// TODO: Call maybe_propose_first_closing_signed on restoration (or call it here and
 			// re-send the message on restoration)
-			return Err((Some(monitor_update), ChannelError::Ignore("Previous monitor update failure prevented generation of RAA")));
+			return Err((Some(monitor_update), ChannelError::Ignore("Previous monitor update failure prevented generation of RAA".to_owned())));
 		}
 
 		let (our_commitment_signed, closing_signed) = if need_our_commitment && (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == 0 {
@@ -2116,7 +2119,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 	/// Used to fulfill holding_cell_htlcs when we get a remote ack (or implicitly get it by them
 	/// fulfilling or failing the last pending HTLC)
-	fn free_holding_cell_htlcs<L: Deref>(&mut self, logger: &L) -> Result<Option<(msgs::CommitmentUpdate, ChannelMonitorUpdate)>, ChannelError> where L::Target: Logger {
+	fn free_holding_cell_htlcs<L: Deref>(&mut self, logger: &L) -> Result<(Option<(msgs::CommitmentUpdate, ChannelMonitorUpdate)>, Vec<(HTLCSource, PaymentHash)>), ChannelError> where L::Target: Logger {
 		assert_eq!(self.channel_state & ChannelState::MonitorUpdateFailed as u32, 0);
 		if self.holding_cell_htlc_updates.len() != 0 || self.holding_cell_update_fee.is_some() {
 			log_trace!(logger, "Freeing holding cell with {} HTLC updates{}", self.holding_cell_htlc_updates.len(), if self.holding_cell_update_fee.is_some() { " and a fee update" } else { "" });
@@ -2131,110 +2134,94 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			let mut update_add_htlcs = Vec::with_capacity(htlc_updates.len());
 			let mut update_fulfill_htlcs = Vec::with_capacity(htlc_updates.len());
 			let mut update_fail_htlcs = Vec::with_capacity(htlc_updates.len());
-			let mut err = None;
+			let mut htlcs_to_fail = Vec::new();
 			for htlc_update in htlc_updates.drain(..) {
 				// Note that this *can* fail, though it should be due to rather-rare conditions on
 				// fee races with adding too many outputs which push our total payments just over
 				// the limit. In case it's less rare than I anticipate, we may want to revisit
 				// handling this case better and maybe fulfilling some of the HTLCs while attempting
 				// to rebalance channels.
-				if err.is_some() { // We're back to AwaitingRemoteRevoke (or are about to fail the channel)
-					self.holding_cell_htlc_updates.push(htlc_update);
-				} else {
-					match &htlc_update {
-						&HTLCUpdateAwaitingACK::AddHTLC {amount_msat, cltv_expiry, ref payment_hash, ref source, ref onion_routing_packet, ..} => {
-							match self.send_htlc(amount_msat, *payment_hash, cltv_expiry, source.clone(), onion_routing_packet.clone()) {
-								Ok(update_add_msg_option) => update_add_htlcs.push(update_add_msg_option.unwrap()),
-								Err(e) => {
-									match e {
-										ChannelError::Ignore(ref msg) => {
-											log_info!(logger, "Failed to send HTLC with payment_hash {} due to {}", log_bytes!(payment_hash.0), msg);
-										},
-										_ => {
-											log_info!(logger, "Failed to send HTLC with payment_hash {} resulting in a channel closure during holding_cell freeing", log_bytes!(payment_hash.0));
-										},
-									}
-									err = Some(e);
+				match &htlc_update {
+					&HTLCUpdateAwaitingACK::AddHTLC {amount_msat, cltv_expiry, ref payment_hash, ref source, ref onion_routing_packet, ..} => {
+						match self.send_htlc(amount_msat, *payment_hash, cltv_expiry, source.clone(), onion_routing_packet.clone()) {
+							Ok(update_add_msg_option) => update_add_htlcs.push(update_add_msg_option.unwrap()),
+							Err(e) => {
+								match e {
+									ChannelError::Ignore(ref msg) => {
+										log_info!(logger, "Failed to send HTLC with payment_hash {} due to {}", log_bytes!(payment_hash.0), msg);
+										// If we fail to send here, then this HTLC should
+										// be failed backwards. Failing to send here
+										// indicates that this HTLC may keep being put back
+										// into the holding cell without ever being
+										// successfully forwarded/failed/fulfilled, causing
+										// our counterparty to eventually close on us.
+										htlcs_to_fail.push((source.clone(), *payment_hash));
+									},
+									_ => {
+										panic!("Got a non-IgnoreError action trying to send holding cell HTLC");
+									},
 								}
 							}
-						},
-						&HTLCUpdateAwaitingACK::ClaimHTLC { ref payment_preimage, htlc_id, .. } => {
-							match self.get_update_fulfill_htlc(htlc_id, *payment_preimage, logger) {
-								Ok((update_fulfill_msg_option, additional_monitor_update_opt)) => {
-									update_fulfill_htlcs.push(update_fulfill_msg_option.unwrap());
-									if let Some(mut additional_monitor_update) = additional_monitor_update_opt {
-										monitor_update.updates.append(&mut additional_monitor_update.updates);
-									}
-								},
-								Err(e) => {
-									if let ChannelError::Ignore(_) = e {}
-									else {
-										panic!("Got a non-IgnoreError action trying to fulfill holding cell HTLC");
-									}
+						}
+					},
+					&HTLCUpdateAwaitingACK::ClaimHTLC { ref payment_preimage, htlc_id, .. } => {
+						match self.get_update_fulfill_htlc(htlc_id, *payment_preimage, logger) {
+							Ok((update_fulfill_msg_option, additional_monitor_update_opt)) => {
+								update_fulfill_htlcs.push(update_fulfill_msg_option.unwrap());
+								if let Some(mut additional_monitor_update) = additional_monitor_update_opt {
+									monitor_update.updates.append(&mut additional_monitor_update.updates);
+								}
+							},
+							Err(e) => {
+								if let ChannelError::Ignore(_) = e {}
+								else {
+									panic!("Got a non-IgnoreError action trying to fulfill holding cell HTLC");
 								}
 							}
-						},
-						&HTLCUpdateAwaitingACK::FailHTLC { htlc_id, ref err_packet } => {
-							match self.get_update_fail_htlc(htlc_id, err_packet.clone()) {
-								Ok(update_fail_msg_option) => update_fail_htlcs.push(update_fail_msg_option.unwrap()),
-								Err(e) => {
-									if let ChannelError::Ignore(_) = e {}
-									else {
-										panic!("Got a non-IgnoreError action trying to fail holding cell HTLC");
-									}
+						}
+					},
+					&HTLCUpdateAwaitingACK::FailHTLC { htlc_id, ref err_packet } => {
+						match self.get_update_fail_htlc(htlc_id, err_packet.clone()) {
+							Ok(update_fail_msg_option) => update_fail_htlcs.push(update_fail_msg_option.unwrap()),
+							Err(e) => {
+								if let ChannelError::Ignore(_) = e {}
+								else {
+									panic!("Got a non-IgnoreError action trying to fail holding cell HTLC");
 								}
 							}
-						},
-					}
-					if err.is_some() {
-						self.holding_cell_htlc_updates.push(htlc_update);
-						if let Some(ChannelError::Ignore(_)) = err {
-							// If we failed to add the HTLC, but got an Ignore error, we should
-							// still send the new commitment_signed, so reset the err to None.
-							err = None;
 						}
-					}
+					},
 				}
 			}
-			//TODO: Need to examine the type of err - if it's a fee issue or similar we may want to
-			//fail it back the route, if it's a temporary issue we can ignore it...
-			match err {
-				None => {
-					if update_add_htlcs.is_empty() && update_fulfill_htlcs.is_empty() && update_fail_htlcs.is_empty() && self.holding_cell_update_fee.is_none() {
-						// This should never actually happen and indicates we got some Errs back
-						// from update_fulfill_htlc/update_fail_htlc, but we handle it anyway in
-						// case there is some strange way to hit duplicate HTLC removes.
-						return Ok(None);
-					}
-					let update_fee = if let Some(feerate) = self.holding_cell_update_fee {
-							self.pending_update_fee = self.holding_cell_update_fee.take();
-							Some(msgs::UpdateFee {
-								channel_id: self.channel_id,
-								feerate_per_kw: feerate as u32,
-							})
-						} else {
-							None
-						};
+			if update_add_htlcs.is_empty() && update_fulfill_htlcs.is_empty() && update_fail_htlcs.is_empty() && self.holding_cell_update_fee.is_none() {
+				return Ok((None, htlcs_to_fail));
+			}
+			let update_fee = if let Some(feerate) = self.holding_cell_update_fee {
+				self.pending_update_fee = self.holding_cell_update_fee.take();
+				Some(msgs::UpdateFee {
+					channel_id: self.channel_id,
+					feerate_per_kw: feerate as u32,
+				})
+			} else {
+				None
+			};
 
-					let (commitment_signed, mut additional_update) = self.send_commitment_no_status_check(logger)?;
-					// send_commitment_no_status_check and get_update_fulfill_htlc may bump latest_monitor_id
-					// but we want them to be strictly increasing by one, so reset it here.
-					self.latest_monitor_update_id = monitor_update.update_id;
-					monitor_update.updates.append(&mut additional_update.updates);
+			let (commitment_signed, mut additional_update) = self.send_commitment_no_status_check(logger)?;
+			// send_commitment_no_status_check and get_update_fulfill_htlc may bump latest_monitor_id
+			// but we want them to be strictly increasing by one, so reset it here.
+			self.latest_monitor_update_id = monitor_update.update_id;
+			monitor_update.updates.append(&mut additional_update.updates);
 
-					Ok(Some((msgs::CommitmentUpdate {
-						update_add_htlcs,
-						update_fulfill_htlcs,
-						update_fail_htlcs,
-						update_fail_malformed_htlcs: Vec::new(),
-						update_fee: update_fee,
-						commitment_signed,
-					}, monitor_update)))
-				},
-				Some(e) => Err(e)
-			}
+			Ok((Some((msgs::CommitmentUpdate {
+				update_add_htlcs,
+				update_fulfill_htlcs,
+				update_fail_htlcs,
+				update_fail_malformed_htlcs: Vec::new(),
+				update_fee: update_fee,
+				commitment_signed,
+			}, monitor_update)), htlcs_to_fail))
 		} else {
-			Ok(None)
+			Ok((None, Vec::new()))
 		}
 	}
 
@@ -2243,23 +2230,23 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 	/// waiting on this revoke_and_ack. The generation of this new commitment_signed may also fail,
 	/// generating an appropriate error *after* the channel state has been updated based on the
 	/// revoke_and_ack message.
-	pub fn revoke_and_ack<F: Deref, L: Deref>(&mut self, msg: &msgs::RevokeAndACK, fee_estimator: &F, logger: &L) -> Result<(Option<msgs::CommitmentUpdate>, Vec<(PendingHTLCInfo, u64)>, Vec<(HTLCSource, PaymentHash, HTLCFailReason)>, Option<msgs::ClosingSigned>, ChannelMonitorUpdate), ChannelError>
+	pub fn revoke_and_ack<F: Deref, L: Deref>(&mut self, msg: &msgs::RevokeAndACK, fee_estimator: &F, logger: &L) -> Result<(Option<msgs::CommitmentUpdate>, Vec<(PendingHTLCInfo, u64)>, Vec<(HTLCSource, PaymentHash, HTLCFailReason)>, Option<msgs::ClosingSigned>, ChannelMonitorUpdate, Vec<(HTLCSource, PaymentHash)>), ChannelError>
 		where F::Target: FeeEstimator,
 					L::Target: Logger,
 	{
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-			return Err(ChannelError::Close("Got revoke/ACK message when channel was not in an operational state"));
+			return Err(ChannelError::Close("Got revoke/ACK message when channel was not in an operational state".to_owned()));
 		}
 		if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-			return Err(ChannelError::Close("Peer sent revoke_and_ack when we needed a channel_reestablish"));
+			return Err(ChannelError::Close("Peer sent revoke_and_ack when we needed a channel_reestablish".to_owned()));
 		}
 		if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK == BOTH_SIDES_SHUTDOWN_MASK && self.last_sent_closing_fee.is_some() {
-			return Err(ChannelError::Close("Peer sent revoke_and_ack after we'd started exchanging closing_signeds"));
+			return Err(ChannelError::Close("Peer sent revoke_and_ack after we'd started exchanging closing_signeds".to_owned()));
 		}
 
 		if let Some(their_prev_commitment_point) = self.their_prev_commitment_point {
-			if PublicKey::from_secret_key(&self.secp_ctx, &secp_check!(SecretKey::from_slice(&msg.per_commitment_secret), "Peer provided an invalid per_commitment_secret")) != their_prev_commitment_point {
-				return Err(ChannelError::Close("Got a revoke commitment secret which didn't correspond to their current pubkey"));
+			if PublicKey::from_secret_key(&self.secp_ctx, &secp_check!(SecretKey::from_slice(&msg.per_commitment_secret), "Peer provided an invalid per_commitment_secret".to_owned())) != their_prev_commitment_point {
+				return Err(ChannelError::Close("Got a revoke commitment secret which didn't correspond to their current pubkey".to_owned()));
 			}
 		}
 
@@ -2271,11 +2258,11 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			// lot of work, and there's some chance this is all a misunderstanding anyway.
 			// We have to do *something*, though, since our signer may get mad at us for otherwise
 			// jumping a remote commitment number, so best to just force-close and move on.
-			return Err(ChannelError::Close("Received an unexpected revoke_and_ack"));
+			return Err(ChannelError::Close("Received an unexpected revoke_and_ack".to_owned()));
 		}
 
 		self.commitment_secrets.provide_secret(self.cur_remote_commitment_transaction_number + 1, msg.per_commitment_secret)
-			.map_err(|_| ChannelError::Close("Previous secrets did not match new one"))?;
+			.map_err(|_| ChannelError::Close("Previous secrets did not match new one".to_owned()))?;
 		self.latest_monitor_update_id += 1;
 		let mut monitor_update = ChannelMonitorUpdate {
 			update_id: self.latest_monitor_update_id,
@@ -2284,7 +2271,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				secret: msg.per_commitment_secret,
 			}],
 		};
-		self.channel_monitor.as_mut().unwrap().update_monitor_ooo(monitor_update.clone(), logger).unwrap();
 
 		// Update state now that we've passed all the can-fail calls...
 		// (note that we may still fail to generate the new commitment_signed message, but that's
@@ -2418,11 +2404,11 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			}
 			self.monitor_pending_forwards.append(&mut to_forward_infos);
 			self.monitor_pending_failures.append(&mut revoked_htlcs);
-			return Ok((None, Vec::new(), Vec::new(), None, monitor_update))
+			return Ok((None, Vec::new(), Vec::new(), None, monitor_update, Vec::new()))
 		}
 
 		match self.free_holding_cell_htlcs(logger)? {
-			Some((mut commitment_update, mut additional_update)) => {
+			(Some((mut commitment_update, mut additional_update)), htlcs_to_fail) => {
 				commitment_update.update_fail_htlcs.reserve(update_fail_htlcs.len());
 				for fail_msg in update_fail_htlcs.drain(..) {
 					commitment_update.update_fail_htlcs.push(fail_msg);
@@ -2437,9 +2423,9 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				self.latest_monitor_update_id = monitor_update.update_id;
 				monitor_update.updates.append(&mut additional_update.updates);
 
-				Ok((Some(commitment_update), to_forward_infos, revoked_htlcs, None, monitor_update))
+				Ok((Some(commitment_update), to_forward_infos, revoked_htlcs, None, monitor_update, htlcs_to_fail))
 			},
-			None => {
+			(None, htlcs_to_fail) => {
 				if require_commitment {
 					let (commitment_signed, mut additional_update) = self.send_commitment_no_status_check(logger)?;
 
@@ -2455,9 +2441,9 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 						update_fail_malformed_htlcs,
 						update_fee: None,
 						commitment_signed
-					}), to_forward_infos, revoked_htlcs, None, monitor_update))
+					}), to_forward_infos, revoked_htlcs, None, monitor_update, htlcs_to_fail))
 				} else {
-					Ok((None, to_forward_infos, revoked_htlcs, self.maybe_propose_first_closing_signed(fee_estimator), monitor_update))
+					Ok((None, to_forward_infos, revoked_htlcs, self.maybe_propose_first_closing_signed(fee_estimator), monitor_update, htlcs_to_fail))
 				}
 			}
 		}
@@ -2559,6 +2545,11 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 		self.holding_cell_htlc_updates.retain(|htlc_update| {
 			match htlc_update {
+				// Note that currently on channel reestablish we assert that there are
+				// no holding cell HTLC update_adds, so if in the future we stop
+				// dropping added HTLCs here and failing them backwards, then there will
+				// need to be corresponding changes made in the Channel's re-establish
+				// logic.
 				&HTLCUpdateAwaitingACK::AddHTLC { ref payment_hash, ref source, .. } => {
 					outbound_drops.push((source.clone(), payment_hash.clone()));
 					false
@@ -2606,8 +2597,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		let funding_locked = if self.monitor_pending_funding_locked {
 			assert!(!self.channel_outbound, "Funding transaction broadcast without FundingBroadcastSafe!");
 			self.monitor_pending_funding_locked = false;
-			let next_per_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number);
-			let next_per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &next_per_commitment_secret);
+			let next_per_commitment_point = self.local_keys.get_per_commitment_point(self.cur_local_commitment_transaction_number, &self.secp_ctx);
 			Some(msgs::FundingLocked {
 				channel_id: self.channel_id(),
 				next_per_commitment_point: next_per_commitment_point,
@@ -2647,10 +2637,10 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		where F::Target: FeeEstimator
 	{
 		if self.channel_outbound {
-			return Err(ChannelError::Close("Non-funding remote tried to update channel fee"));
+			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"));
+			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)?;
 		self.pending_update_fee = Some(msg.feerate_per_kw);
@@ -2659,8 +2649,8 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 	}
 
 	fn get_last_revoke_and_ack(&self) -> msgs::RevokeAndACK {
-		let next_per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &self.build_local_commitment_secret(self.cur_local_commitment_transaction_number));
-		let per_commitment_secret = self.local_keys.commitment_secret(self.cur_local_commitment_transaction_number + 2);
+		let next_per_commitment_point = self.local_keys.get_per_commitment_point(self.cur_local_commitment_transaction_number, &self.secp_ctx);
+		let per_commitment_secret = self.local_keys.release_commitment_secret(self.cur_local_commitment_transaction_number + 2);
 		msgs::RevokeAndACK {
 			channel_id: self.channel_id,
 			per_commitment_secret,
@@ -2732,23 +2722,26 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			// While BOLT 2 doesn't indicate explicitly we should error this channel here, it
 			// almost certainly indicates we are going to end up out-of-sync in some way, so we
 			// just close here instead of trying to recover.
-			return Err(ChannelError::Close("Peer sent a loose channel_reestablish not after reconnect"));
+			return Err(ChannelError::Close("Peer sent a loose channel_reestablish not after reconnect".to_owned()));
 		}
 
 		if msg.next_local_commitment_number >= INITIAL_COMMITMENT_NUMBER || msg.next_remote_commitment_number >= INITIAL_COMMITMENT_NUMBER ||
 			msg.next_local_commitment_number == 0 {
-			return Err(ChannelError::Close("Peer sent a garbage channel_reestablish"));
+			return Err(ChannelError::Close("Peer sent a garbage channel_reestablish".to_owned()));
 		}
 
 		if msg.next_remote_commitment_number > 0 {
 			match msg.data_loss_protect {
 				OptionalField::Present(ref data_loss) => {
-					if self.local_keys.commitment_secret(INITIAL_COMMITMENT_NUMBER - msg.next_remote_commitment_number + 1) != data_loss.your_last_per_commitment_secret {
-						return Err(ChannelError::Close("Peer sent a garbage channel_reestablish with secret key not matching the commitment height provided"));
+					let expected_point = self.local_keys.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) {
+						return Err(ChannelError::Close("Peer sent a garbage channel_reestablish with secret key not matching the commitment height provided".to_owned()));
 					}
 					if msg.next_remote_commitment_number > INITIAL_COMMITMENT_NUMBER - self.cur_local_commitment_transaction_number {
 						return Err(ChannelError::CloseDelayBroadcast(
-							"We have fallen behind - we have received proof that if we broadcast remote is going to claim our funds - we can't do any automated broadcasting"
+							"We have fallen behind - we have received proof that if we broadcast remote is going to claim our funds - we can't do any automated broadcasting".to_owned()
 						));
 					}
 				},
@@ -2772,15 +2765,14 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			if self.channel_state & (ChannelState::OurFundingLocked as u32) == 0 ||
 					self.channel_state & (ChannelState::MonitorUpdateFailed as u32) != 0 {
 				if msg.next_remote_commitment_number != 0 {
-					return Err(ChannelError::Close("Peer claimed they saw a revoke_and_ack but we haven't sent funding_locked yet"));
+					return Err(ChannelError::Close("Peer claimed they saw a revoke_and_ack but we haven't sent funding_locked yet".to_owned()));
 				}
 				// Short circuit the whole handler as there is nothing we can resend them
 				return Ok((None, None, None, None, RAACommitmentOrder::CommitmentFirst, shutdown_msg));
 			}
 
 			// We have OurFundingLocked set!
-			let next_per_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number);
-			let next_per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &next_per_commitment_secret);
+			let next_per_commitment_point = self.local_keys.get_per_commitment_point(self.cur_local_commitment_transaction_number, &self.secp_ctx);
 			return Ok((Some(msgs::FundingLocked {
 				channel_id: self.channel_id(),
 				next_per_commitment_point: next_per_commitment_point,
@@ -2799,7 +2791,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				Some(self.get_last_revoke_and_ack())
 			}
 		} else {
-			return Err(ChannelError::Close("Peer attempted to reestablish channel with a very old local commitment transaction"));
+			return Err(ChannelError::Close("Peer attempted to reestablish channel with a very old local commitment transaction".to_owned()));
 		};
 
 		// We increment cur_remote_commitment_transaction_number only upon receipt of
@@ -2810,8 +2802,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 		let resend_funding_locked = if msg.next_local_commitment_number == 1 && INITIAL_COMMITMENT_NUMBER - self.cur_local_commitment_transaction_number == 1 {
 			// We should never have to worry about MonitorUpdateFailed resending FundingLocked
-			let next_per_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number);
-			let next_per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &next_per_commitment_secret);
+			let next_per_commitment_point = self.local_keys.get_per_commitment_point(self.cur_local_commitment_transaction_number, &self.secp_ctx);
 			Some(msgs::FundingLocked {
 				channel_id: self.channel_id(),
 				next_per_commitment_point: next_per_commitment_point,
@@ -2826,6 +2817,14 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			}
 
 			if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateFailed as u32)) == 0 {
+				// Note that if in the future we no longer drop holding cell update_adds on peer
+				// disconnect, this logic will need to be updated.
+				for htlc_update in self.holding_cell_htlc_updates.iter() {
+					if let &HTLCUpdateAwaitingACK::AddHTLC { .. } = htlc_update {
+						debug_assert!(false, "There shouldn't be any add-HTLCs in the holding cell now because they should have been dropped on peer disconnect. Panic here because said HTLCs won't be handled correctly.");
+					}
+				}
+
 				// We're up-to-date and not waiting on a remote revoke (if we are our
 				// channel_reestablish should result in them sending a revoke_and_ack), but we may
 				// have received some updates while we were disconnected. Free the holding cell
@@ -2833,8 +2832,18 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				match self.free_holding_cell_htlcs(logger) {
 					Err(ChannelError::Close(msg)) => return Err(ChannelError::Close(msg)),
 					Err(ChannelError::Ignore(_)) | Err(ChannelError::CloseDelayBroadcast(_)) => panic!("Got non-channel-failing result from free_holding_cell_htlcs"),
-					Ok(Some((commitment_update, monitor_update))) => return Ok((resend_funding_locked, required_revoke, Some(commitment_update), Some(monitor_update), self.resend_order.clone(), shutdown_msg)),
-					Ok(None) => return Ok((resend_funding_locked, required_revoke, None, None, self.resend_order.clone(), shutdown_msg)),
+					Ok((Some((commitment_update, monitor_update)), htlcs_to_fail)) => {
+						// If in the future we no longer drop holding cell update_adds on peer
+						// disconnect, we may be handed some HTLCs to fail backwards here.
+						assert!(htlcs_to_fail.is_empty());
+						return Ok((resend_funding_locked, required_revoke, Some(commitment_update), Some(monitor_update), self.resend_order.clone(), shutdown_msg));
+					},
+					Ok((None, htlcs_to_fail)) => {
+						// If in the future we no longer drop holding cell update_adds on peer
+						// disconnect, we may be handed some HTLCs to fail backwards here.
+						assert!(htlcs_to_fail.is_empty());
+						return Ok((resend_funding_locked, required_revoke, None, None, self.resend_order.clone(), shutdown_msg));
+					},
 				}
 			} else {
 				return Ok((resend_funding_locked, required_revoke, None, None, self.resend_order.clone(), shutdown_msg));
@@ -2853,7 +2862,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 			return Ok((resend_funding_locked, required_revoke, Some(self.get_last_commitment_update(logger)), None, self.resend_order.clone(), shutdown_msg));
 		} else {
-			return Err(ChannelError::Close("Peer attempted to reestablish channel with a very old remote commitment transaction"));
+			return Err(ChannelError::Close("Peer attempted to reestablish channel with a very old remote commitment transaction".to_owned()));
 		}
 	}
 
@@ -2891,17 +2900,17 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		where F::Target: FeeEstimator
 	{
 		if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-			return Err(ChannelError::Close("Peer sent shutdown when we needed a channel_reestablish"));
+			return Err(ChannelError::Close("Peer sent shutdown when we needed a channel_reestablish".to_owned()));
 		}
 		if self.channel_state < ChannelState::FundingSent as u32 {
 			// Spec says we should fail the connection, not the channel, but that's nonsense, there
 			// are plenty of reasons you may want to fail a channel pre-funding, and spec says you
 			// can do that via error message without getting a connection fail anyway...
-			return Err(ChannelError::Close("Peer sent shutdown pre-funding generation"));
+			return Err(ChannelError::Close("Peer sent shutdown pre-funding generation".to_owned()));
 		}
 		for htlc in self.pending_inbound_htlcs.iter() {
 			if let InboundHTLCState::RemoteAnnounced(_) = htlc.state {
-				return Err(ChannelError::Close("Got shutdown with remote pending HTLCs"));
+				return Err(ChannelError::Close("Got shutdown with remote pending HTLCs".to_owned()));
 			}
 		}
 		assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
@@ -2909,17 +2918,17 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		// 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("Got shutdown_scriptpubkey of absurd length from remote peer"));
+			return Err(ChannelError::Close(format!("Got shutdown_scriptpubkey ({}) of absurd length from remote peer", msg.scriptpubkey.to_bytes().to_hex())));
 		}
 
 		//Check 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() {
-			return Err(ChannelError::Close("Got a nonstandard scriptpubkey from remote peer"));
+			return Err(ChannelError::Close(format!("Got a nonstandard scriptpubkey ({}) from remote peer", msg.scriptpubkey.to_bytes().to_hex())));
 		}
 
 		if self.their_shutdown_scriptpubkey.is_some() {
 			if Some(&msg.scriptpubkey) != self.their_shutdown_scriptpubkey.as_ref() {
-				return Err(ChannelError::Close("Got shutdown request with a scriptpubkey which did not match their previous scriptpubkey"));
+				return Err(ChannelError::Close(format!("Got shutdown request with a scriptpubkey ({}) which did not match their previous scriptpubkey.", msg.scriptpubkey.to_bytes().to_hex())));
 			}
 		} else {
 			self.their_shutdown_scriptpubkey = Some(msg.scriptpubkey.clone());
@@ -2989,22 +2998,22 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		where F::Target: FeeEstimator
 	{
 		if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK != BOTH_SIDES_SHUTDOWN_MASK {
-			return Err(ChannelError::Close("Remote end sent us a closing_signed before both sides provided a shutdown"));
+			return Err(ChannelError::Close("Remote end sent us a closing_signed before both sides provided a shutdown".to_owned()));
 		}
 		if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-			return Err(ChannelError::Close("Peer sent closing_signed when we needed a channel_reestablish"));
+			return Err(ChannelError::Close("Peer sent closing_signed when we needed a channel_reestablish".to_owned()));
 		}
 		if !self.pending_inbound_htlcs.is_empty() || !self.pending_outbound_htlcs.is_empty() {
-			return Err(ChannelError::Close("Remote end sent us a closing_signed while there were still pending HTLCs"));
+			return Err(ChannelError::Close("Remote end sent us a closing_signed while there were still pending HTLCs".to_owned()));
 		}
 		if msg.fee_satoshis > 21000000 * 10000000 { //this is required to stop potential overflow in build_closing_transaction
-			return Err(ChannelError::Close("Remote tried to send us a closing tx with > 21 million BTC fee"));
+			return Err(ChannelError::Close("Remote tried to send us a closing tx with > 21 million BTC fee".to_owned()));
 		}
 
 		let funding_redeemscript = self.get_funding_redeemscript();
 		let (mut closing_tx, used_total_fee) = self.build_closing_transaction(msg.fee_satoshis, false);
 		if used_total_fee != msg.fee_satoshis {
-			return Err(ChannelError::Close("Remote sent us a closing_signed with a fee greater than the value they can claim"));
+			return Err(ChannelError::Close(format!("Remote sent us a closing_signed with a fee greater than the value they can claim. Fee in message: {}", msg.fee_satoshis)));
 		}
 		let mut sighash = hash_to_message!(&bip143::SighashComponents::new(&closing_tx).sighash_all(&closing_tx.input[0], &funding_redeemscript, self.channel_value_satoshis)[..]);
 
@@ -3017,7 +3026,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				// limits, so check for that case by re-checking the signature here.
 				closing_tx = self.build_closing_transaction(msg.fee_satoshis, true).0;
 				sighash = hash_to_message!(&bip143::SighashComponents::new(&closing_tx).sighash_all(&closing_tx.input[0], &funding_redeemscript, self.channel_value_satoshis)[..]);
-				secp_check!(self.secp_ctx.verify(&sighash, &msg.signature, self.their_funding_pubkey()), "Invalid closing tx signature from peer");
+				secp_check!(self.secp_ctx.verify(&sighash, &msg.signature, self.their_funding_pubkey()), "Invalid closing tx signature from peer".to_owned());
 			},
 		};
 
@@ -3036,7 +3045,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				let (closing_tx, used_total_fee) = self.build_closing_transaction($new_feerate as u64 * closing_tx_max_weight / 1000, false);
 				let our_sig = self.local_keys
 					.sign_closing_transaction(&closing_tx, &self.secp_ctx)
-					.map_err(|_| ChannelError::Close("External signer refused to sign closing transaction"))?;
+					.map_err(|_| ChannelError::Close("External signer refused to sign closing transaction".to_owned()))?;
 				self.last_sent_closing_fee = Some(($new_feerate, used_total_fee, our_sig.clone()));
 				return Ok((Some(msgs::ClosingSigned {
 					channel_id: self.channel_id,
@@ -3052,7 +3061,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			if (proposed_sat_per_kw as u32) > our_max_feerate {
 				if let Some((last_feerate, _, _)) = self.last_sent_closing_fee {
 					if our_max_feerate <= last_feerate {
-						return Err(ChannelError::Close("Unable to come to consensus about closing feerate, remote wanted something higher than our Normal feerate"));
+						return Err(ChannelError::Close(format!("Unable to come to consensus about closing feerate, remote wanted something higher ({}) than our Normal feerate ({})", last_feerate, our_max_feerate)));
 					}
 				}
 				propose_new_feerate!(our_max_feerate);
@@ -3062,7 +3071,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			if (proposed_sat_per_kw as u32) < our_min_feerate {
 				if let Some((last_feerate, _, _)) = self.last_sent_closing_fee {
 					if our_min_feerate >= last_feerate {
-						return Err(ChannelError::Close("Unable to come to consensus about closing feerate, remote wanted something lower than our Background feerate"));
+						return Err(ChannelError::Close(format!("Unable to come to consensus about closing feerate, remote wanted something lower ({}) than our Background feerate ({}).", last_feerate, our_min_feerate)));
 					}
 				}
 				propose_new_feerate!(our_min_feerate);
@@ -3071,7 +3080,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 		let our_sig = self.local_keys
 			.sign_closing_transaction(&closing_tx, &self.secp_ctx)
-			.map_err(|_| ChannelError::Close("External signer refused to sign closing transaction"))?;
+			.map_err(|_| ChannelError::Close("External signer refused to sign closing transaction".to_owned()))?;
 		self.build_signed_closing_transaction(&mut closing_tx, &msg.signature, &our_sig);
 
 		self.channel_state = ChannelState::ShutdownComplete as u32;
@@ -3096,14 +3105,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		self.user_id
 	}
 
-	/// May only be called after funding has been initiated (ie is_funding_initiated() is true)
-	pub fn channel_monitor(&mut self) -> &mut ChannelMonitor<ChanSigner> {
-		if self.channel_state < ChannelState::FundingSent as u32 {
-			panic!("Can't get a channel monitor until funding has been created");
-		}
-		self.channel_monitor.as_mut().unwrap()
-	}
-
 	/// Guaranteed to be Some after both FundingLocked messages have been exchanged (and, thus,
 	/// is_usable() returns true).
 	/// Allowed in any state (including after shutdown)
@@ -3127,6 +3128,18 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		self.our_htlc_minimum_msat
 	}
 
+	/// Allowed in any state (including after shutdown)
+	pub fn get_announced_htlc_max_msat(&self) -> u64 {
+		return cmp::min(
+			// Upper bound by capacity. We make it a bit less than full capacity to prevent attempts
+			// to use full capacity. This is an effort to reduce routing failures, because in many cases
+			// channel might have been used to route very small values (either by honest users or as DoS).
+			self.channel_value_satoshis * 9 / 10,
+
+			Channel::<ChanSigner>::get_our_max_htlc_value_in_flight_msat(self.channel_value_satoshis)
+		);
+	}
+
 	/// Allowed in any state (including after shutdown)
 	pub fn get_their_htlc_minimum_msat(&self) -> u64 {
 		self.our_htlc_minimum_msat
@@ -3366,9 +3379,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		if header.bitcoin_hash() != self.last_block_connected {
 			self.last_block_connected = header.bitcoin_hash();
 			self.update_time_counter = cmp::max(self.update_time_counter, header.time);
-			if let Some(channel_monitor) = self.channel_monitor.as_mut() {
-				channel_monitor.last_block_hash = self.last_block_connected;
-			}
 			if self.funding_tx_confirmations > 0 {
 				if self.funding_tx_confirmations == self.minimum_depth as u64 {
 					let need_commitment_update = if non_shutdown_state == ChannelState::FundingSent as u32 {
@@ -3397,8 +3407,7 @@ 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_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number);
-							let next_per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &next_per_commitment_secret);
+							let next_per_commitment_point = self.local_keys.get_per_commitment_point(self.cur_local_commitment_transaction_number, &self.secp_ctx);
 							return Ok((Some(msgs::FundingLocked {
 								channel_id: self.channel_id,
 								next_per_commitment_point: next_per_commitment_point,
@@ -3428,9 +3437,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			self.funding_tx_confirmations = self.minimum_depth as u64 - 1;
 		}
 		self.last_block_connected = header.bitcoin_hash();
-		if let Some(channel_monitor) = self.channel_monitor.as_mut() {
-			channel_monitor.last_block_hash = self.last_block_connected;
-		}
 		false
 	}
 
@@ -3449,7 +3455,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			panic!("Tried to send an open_channel for a channel that has already advanced");
 		}
 
-		let local_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number);
+		let first_per_commitment_point = self.local_keys.get_per_commitment_point(self.cur_local_commitment_transaction_number, &self.secp_ctx);
 		let local_keys = self.local_keys.pubkeys();
 
 		msgs::OpenChannel {
@@ -3469,7 +3475,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			payment_point: local_keys.payment_point,
 			delayed_payment_basepoint: local_keys.delayed_payment_basepoint,
 			htlc_basepoint: local_keys.htlc_basepoint,
-			first_per_commitment_point: PublicKey::from_secret_key(&self.secp_ctx, &local_commitment_secret),
+			first_per_commitment_point,
 			channel_flags: if self.config.announced_channel {1} else {0},
 			shutdown_scriptpubkey: OptionalField::Present(if self.config.commit_upfront_shutdown_pubkey { self.get_closing_scriptpubkey() } else { Builder::new().into_script() })
 		}
@@ -3486,7 +3492,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			panic!("Tried to send an accept_channel for a channel that has already advanced");
 		}
 
-		let local_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number);
+		let first_per_commitment_point = self.local_keys.get_per_commitment_point(self.cur_local_commitment_transaction_number, &self.secp_ctx);
 		let local_keys = self.local_keys.pubkeys();
 
 		msgs::AcceptChannel {
@@ -3503,7 +3509,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			payment_point: local_keys.payment_point,
 			delayed_payment_basepoint: local_keys.delayed_payment_basepoint,
 			htlc_basepoint: local_keys.htlc_basepoint,
-			first_per_commitment_point: PublicKey::from_secret_key(&self.secp_ctx, &local_commitment_secret),
+			first_per_commitment_point,
 			shutdown_scriptpubkey: OptionalField::Present(if self.config.commit_upfront_shutdown_pubkey { self.get_closing_scriptpubkey() } else { Builder::new().into_script() })
 		}
 	}
@@ -3512,8 +3518,9 @@ 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 remote_keys = self.build_remote_transaction_keys()?;
 		let remote_initial_commitment_tx = self.build_commitment_transaction(self.cur_remote_commitment_transaction_number, &remote_keys, false, false, self.feerate_per_kw, logger).0;
-		Ok(self.local_keys.sign_remote_commitment(self.feerate_per_kw, &remote_initial_commitment_tx, &remote_keys, &Vec::new(), self.our_to_self_delay, &self.secp_ctx)
-				.map_err(|_| ChannelError::Close("Failed to get signatures for new commitment_signed"))?.0)
+		let pre_remote_keys = PreCalculatedTxCreationKeys::new(remote_keys);
+		Ok(self.local_keys.sign_remote_commitment(self.feerate_per_kw, &remote_initial_commitment_tx, &pre_remote_keys, &Vec::new(), &self.secp_ctx)
+				.map_err(|_| ChannelError::Close("Failed to get signatures for new commitment_signed".to_owned()))?.0)
 	}
 
 	/// Updates channel state with knowledge of the funding transaction's txid/index, and generates
@@ -3571,13 +3578,13 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 	/// https://github.com/lightningnetwork/lightning-rfc/issues/468
 	pub fn get_channel_announcement(&self, our_node_id: PublicKey, chain_hash: BlockHash) -> Result<(msgs::UnsignedChannelAnnouncement, Signature), ChannelError> {
 		if !self.config.announced_channel {
-			return Err(ChannelError::Ignore("Channel is not available for public announcements"));
+			return Err(ChannelError::Ignore("Channel is not available for public announcements".to_owned()));
 		}
 		if self.channel_state & (ChannelState::ChannelFunded as u32) == 0 {
-			return Err(ChannelError::Ignore("Cannot get a ChannelAnnouncement until the channel funding has been locked"));
+			return Err(ChannelError::Ignore("Cannot get a ChannelAnnouncement until the channel funding has been locked".to_owned()));
 		}
 		if (self.channel_state & (ChannelState::LocalShutdownSent as u32 | ChannelState::ShutdownComplete as u32)) != 0 {
-			return Err(ChannelError::Ignore("Cannot get a ChannelAnnouncement once the channel is closing"));
+			return Err(ChannelError::Ignore("Cannot get a ChannelAnnouncement once the channel is closing".to_owned()));
 		}
 
 		let were_node_one = our_node_id.serialize()[..] < self.their_node_id.serialize()[..];
@@ -3594,7 +3601,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		};
 
 		let sig = self.local_keys.sign_channel_announcement(&msg, &self.secp_ctx)
-			.map_err(|_| ChannelError::Ignore("Signer rejected channel_announcement"))?;
+			.map_err(|_| ChannelError::Ignore("Signer rejected channel_announcement".to_owned()))?;
 
 		Ok((msg, sig))
 	}
@@ -3662,19 +3669,19 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 	/// If an Err is returned, it's a ChannelError::Ignore!
 	pub fn send_htlc(&mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource, onion_routing_packet: msgs::OnionPacket) -> Result<Option<msgs::UpdateAddHTLC>, ChannelError> {
 		if (self.channel_state & (ChannelState::ChannelFunded as u32 | BOTH_SIDES_SHUTDOWN_MASK)) != (ChannelState::ChannelFunded as u32) {
-			return Err(ChannelError::Ignore("Cannot send HTLC until channel is fully established and we haven't started shutting down"));
+			return Err(ChannelError::Ignore("Cannot send HTLC until channel is fully established and we haven't started shutting down".to_owned()));
 		}
-
-		if amount_msat > self.channel_value_satoshis * 1000 {
-			return Err(ChannelError::Ignore("Cannot send more than the total value of the channel"));
+		let channel_total_msat = self.channel_value_satoshis * 1000;
+		if amount_msat > channel_total_msat {
+			return Err(ChannelError::Ignore(format!("Cannot send amount {}, because it is more than the total value of the channel {}", amount_msat, channel_total_msat)));
 		}
 
 		if amount_msat == 0 {
-			return Err(ChannelError::Ignore("Cannot send 0-msat HTLC"));
+			return Err(ChannelError::Ignore("Cannot send 0-msat HTLC".to_owned()));
 		}
 
 		if amount_msat < self.their_htlc_minimum_msat {
-			return Err(ChannelError::Ignore("Cannot send less than their minimum HTLC value"));
+			return Err(ChannelError::Ignore(format!("Cannot send less than their minimum HTLC value ({})", self.their_htlc_minimum_msat)));
 		}
 
 		if (self.channel_state & (ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32)) != 0 {
@@ -3684,16 +3691,16 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			// disconnected during the time the previous hop was doing the commitment dance we may
 			// end up getting here after the forwarding delay. In any case, returning an
 			// IgnoreError will get ChannelManager to do the right thing and fail backwards now.
-			return Err(ChannelError::Ignore("Cannot send an HTLC while disconnected/frozen for channel monitor update"));
+			return Err(ChannelError::Ignore("Cannot send an HTLC while disconnected/frozen for channel monitor update".to_owned()));
 		}
 
 		let (outbound_htlc_count, htlc_outbound_value_msat) = self.get_outbound_pending_htlc_stats();
 		if outbound_htlc_count + 1 > self.their_max_accepted_htlcs as u32 {
-			return Err(ChannelError::Ignore("Cannot push more than their max accepted HTLCs"));
+			return Err(ChannelError::Ignore(format!("Cannot push more than their max accepted HTLCs ({})", self.their_max_accepted_htlcs)));
 		}
 		// Check their_max_htlc_value_in_flight_msat
 		if htlc_outbound_value_msat + amount_msat > self.their_max_htlc_value_in_flight_msat {
-			return Err(ChannelError::Ignore("Cannot send value that would put us over the max HTLC value in flight our peer will accept"));
+			return Err(ChannelError::Ignore(format!("Cannot send value that would put us over the max HTLC value in flight our peer will accept ({})", self.their_max_htlc_value_in_flight_msat)));
 		}
 
 		if !self.channel_outbound {
@@ -3704,13 +3711,13 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			// 1 additional HTLC corresponding to this HTLC.
 			let remote_commit_tx_fee_msat = self.next_remote_commit_tx_fee_msat(1);
 			if remote_balance_msat < remote_chan_reserve_msat + remote_commit_tx_fee_msat {
-				return Err(ChannelError::Ignore("Cannot send value that would put them under remote channel reserve value"));
+				return Err(ChannelError::Ignore("Cannot send value that would put them under remote channel reserve value".to_owned()));
 			}
 		}
 
 		let pending_value_to_self_msat = self.value_to_self_msat - htlc_outbound_value_msat;
 		if pending_value_to_self_msat < amount_msat {
-			return Err(ChannelError::Ignore("Cannot send value that would overdraw remaining funds"));
+			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
@@ -3719,14 +3726,14 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			2 * self.next_local_commit_tx_fee_msat(1 + 1)
 		} else { 0 };
 		if pending_value_to_self_msat - amount_msat < local_commit_tx_fee_msat {
-			return Err(ChannelError::Ignore("Cannot send value that would not leave enough to pay for fees"));
+			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, local_commit_tx_fee_msat)));
 		}
 
 		// Check self.local_channel_reserve_satoshis (the amount we must keep as
 		// reserve for the remote to have something to claim if we misbehave)
 		let chan_reserve_msat = self.local_channel_reserve_satoshis * 1000;
 		if pending_value_to_self_msat - amount_msat - local_commit_tx_fee_msat < chan_reserve_msat {
-			return Err(ChannelError::Ignore("Cannot send value that would put us under local channel reserve value"));
+			return Err(ChannelError::Ignore(format!("Cannot send value that would put us under local channel reserve value ({})", chan_reserve_msat)));
 		}
 
 		// Now update local state:
@@ -3840,7 +3847,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				their_revocation_point: self.their_cur_commitment_point.unwrap()
 			}]
 		};
-		self.channel_monitor.as_mut().unwrap().update_monitor_ooo(monitor_update.clone(), logger).unwrap();
 		self.channel_state |= ChannelState::AwaitingRemoteRevoke as u32;
 		Ok((res, monitor_update))
 	}
@@ -3865,10 +3871,12 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				htlcs.push(htlc);
 			}
 
-			let res = self.local_keys.sign_remote_commitment(feerate_per_kw, &remote_commitment_tx.0, &remote_keys, &htlcs, self.our_to_self_delay, &self.secp_ctx)
-				.map_err(|_| ChannelError::Close("Failed to get signatures for new commitment_signed"))?;
+			let pre_remote_keys = PreCalculatedTxCreationKeys::new(remote_keys);
+			let res = self.local_keys.sign_remote_commitment(feerate_per_kw, &remote_commitment_tx.0, &pre_remote_keys, &htlcs, &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 remote_keys = pre_remote_keys.trust_key_derivation();
 
 			log_trace!(logger, "Signed remote commitment tx {} with redeemscript {} -> {}",
 				encode::serialize_hex(&remote_commitment_tx.0),
@@ -3878,7 +3886,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			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(&remote_commitment_tx.0.txid(), feerate_per_kw, self.our_to_self_delay, htlc, &remote_keys.a_delayed_payment_key, &remote_keys.revocation_key)),
-					encode::serialize_hex(&chan_utils::get_htlc_redeemscript(&htlc, &remote_keys)),
+					encode::serialize_hex(&chan_utils::get_htlc_redeemscript(&htlc, remote_keys)),
 					log_bytes!(remote_keys.a_htlc_key.serialize()),
 					log_bytes!(htlc_sig.serialize_compact()[..]));
 			}
@@ -3910,20 +3918,20 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 	pub fn get_shutdown(&mut self) -> Result<(msgs::Shutdown, Vec<(HTLCSource, PaymentHash)>), APIError> {
 		for htlc in self.pending_outbound_htlcs.iter() {
 			if let OutboundHTLCState::LocalAnnounced(_) = htlc.state {
-				return Err(APIError::APIMisuseError{err: "Cannot begin shutdown with pending HTLCs. Process pending events first"});
+				return Err(APIError::APIMisuseError{err: "Cannot begin shutdown with pending HTLCs. Process pending events first".to_owned()});
 			}
 		}
 		if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK != 0 {
 			if (self.channel_state & ChannelState::LocalShutdownSent as u32) == ChannelState::LocalShutdownSent as u32 {
-				return Err(APIError::APIMisuseError{err: "Shutdown already in progress"});
+				return Err(APIError::APIMisuseError{err: "Shutdown already in progress".to_owned()});
 			}
 			else if (self.channel_state & ChannelState::RemoteShutdownSent as u32) == ChannelState::RemoteShutdownSent as u32 {
-				return Err(APIError::ChannelUnavailable{err: "Shutdown already in progress by remote"});
+				return Err(APIError::ChannelUnavailable{err: "Shutdown already in progress by remote".to_owned()});
 			}
 		}
 		assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
 		if self.channel_state & (ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32) != 0 {
-			return Err(APIError::ChannelUnavailable{err: "Cannot begin shutdown while peer is disconnected or we're waiting on a monitor update, maybe force-close instead?"});
+			return Err(APIError::ChannelUnavailable{err: "Cannot begin shutdown while peer is disconnected or we're waiting on a monitor update, maybe force-close instead?".to_owned()});
 		}
 
 		let our_closing_script = self.get_closing_scriptpubkey();
@@ -4209,8 +4217,6 @@ impl<ChanSigner: ChannelKeys + Writeable> Writeable for Channel<ChanSigner> {
 		self.their_shutdown_scriptpubkey.write(writer)?;
 
 		self.commitment_secrets.write(writer)?;
-
-		self.channel_monitor.as_ref().unwrap().write_for_disk(writer)?;
 		Ok(())
 	}
 }
@@ -4365,13 +4371,6 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
 		let their_shutdown_scriptpubkey = Readable::read(reader)?;
 		let commitment_secrets = Readable::read(reader)?;
 
-		let (monitor_last_block, channel_monitor) = Readable::read(reader)?;
-		// We drop the ChannelMonitor's last block connected hash cause we don't actually bother
-		// doing full block connection operations on the internal ChannelMonitor copies
-		if monitor_last_block != last_block_connected {
-			return Err(DecodeError::InvalidValue);
-		}
-
 		Ok(Channel {
 			user_id,
 
@@ -4443,7 +4442,6 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
 
 			their_shutdown_scriptpubkey,
 
-			channel_monitor: Some(channel_monitor),
 			commitment_secrets,
 
 			network_sync: UpdateStatus::Fresh,
@@ -4658,7 +4656,7 @@ mod tests {
 			delayed_payment_basepoint: public_from_secret_hex(&secp_ctx, "1552dfba4f6cf29a62a0af13c8d6981d36d0ef8d61ba10fb0fe90da7634d7e13"),
 			htlc_basepoint: public_from_secret_hex(&secp_ctx, "4444444444444444444444444444444444444444444444444444444444444444")
 		};
-		chan_keys.set_remote_channel_pubkeys(&their_pubkeys);
+		chan_keys.on_accept(&their_pubkeys, chan.their_to_self_delay, chan.our_to_self_delay);
 
 		assert_eq!(their_pubkeys.payment_point.serialize()[..],
 		           hex::decode("032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991").unwrap()[..]);
@@ -4714,7 +4712,7 @@ mod tests {
 				assert_eq!(serialize(&localtx.add_local_sig(&redeemscript, local_sig))[..],
 						hex::decode($tx_hex).unwrap()[..]);
 
-				let htlc_sigs = chan_keys.sign_local_commitment_htlc_transactions(&localtx, chan.their_to_self_delay, &chan.secp_ctx).unwrap();
+				let htlc_sigs = chan_keys.sign_local_commitment_htlc_transactions(&localtx, &chan.secp_ctx).unwrap();
 				let mut htlc_sig_iter = localtx.per_htlc.iter().zip(htlc_sigs.iter().enumerate());
 
 				$({