Randomize secp contexts for marginally better sidechannel resistance
[rust-lightning] / lightning / src / ln / onchaintx.rs
index 01294bba751cc369405181159e40a0c349da3107..f3d8b2e9489d5078dc79dbc42be835fa54fe56f5 100644 (file)
@@ -9,7 +9,7 @@
 
 //! The logic to build claims and bump in-flight transactions until confirmations.
 //!
-//! OnchainTxHandler objetcs are fully-part of ChannelMonitor and encapsulates all
+//! OnchainTxHandler objects are fully-part of ChannelMonitor and encapsulates all
 //! building, tracking, bumping and notifications functions.
 
 use bitcoin::blockdata::transaction::{Transaction, TxIn, TxOut, SigHashType};
@@ -22,19 +22,20 @@ use bitcoin::secp256k1::{Secp256k1, Signature};
 use bitcoin::secp256k1;
 
 use ln::msgs::DecodeError;
-use ln::channelmonitor::{ANTI_REORG_DELAY, CLTV_SHARED_CLAIM_BUFFER, InputMaterial, ClaimRequest};
 use ln::channelmanager::PaymentPreimage;
 use ln::chan_utils;
-use ln::chan_utils::{TxCreationKeys, LocalCommitmentTransaction};
+use ln::chan_utils::{TxCreationKeys, ChannelTransactionParameters, HolderCommitmentTransaction};
 use chain::chaininterface::{FeeEstimator, BroadcasterInterface, ConfirmationTarget, MIN_RELAY_FEE_SAT_PER_1000_WEIGHT};
-use chain::keysinterface::ChannelKeys;
+use chain::channelmonitor::{ANTI_REORG_DELAY, CLTV_SHARED_CLAIM_BUFFER, InputMaterial, ClaimRequest};
+use chain::keysinterface::{Sign, KeysInterface};
 use util::logger::Logger;
-use util::ser::{Readable, Writer, Writeable};
+use util::ser::{Readable, ReadableArgs, Writer, Writeable, VecWriter};
 use util::byte_utils;
 
 use std::collections::{HashMap, hash_map};
 use std::cmp;
 use std::ops::Deref;
+use std::mem::replace;
 
 const MAX_ALLOC_SIZE: usize = 64*1024;
 
@@ -47,7 +48,7 @@ enum OnchainEvent {
        Claim {
                claim_request: Txid,
        },
-       /// Claim tx aggregate multiple claimable outpoints. One of the outpoint may be claimed by a remote party tx.
+       /// Claim tx aggregate multiple claimable outpoints. One of the outpoint may be claimed by a counterparty party tx.
        /// In this case, we need to drop the outpoint and regenerate a new claim tx. By safety, we keep tracking
        /// the outpoint to be sure to resurect it back to the claim tx if reorgs happen.
        ContentiousOutpoint {
@@ -107,7 +108,7 @@ pub(crate) enum InputDescriptors {
        RevokedReceivedHTLC,
        OfferedHTLC,
        ReceivedHTLC,
-       RevokedOutput, // either a revoked to_local output on commitment tx, a revoked HTLC-Timeout output or a revoked HTLC-Success output
+       RevokedOutput, // either a revoked to_holder output on commitment tx, a revoked HTLC-Timeout output or a revoked HTLC-Success output
 }
 
 impl Writeable for InputDescriptors {
@@ -239,19 +240,18 @@ impl Writeable for Option<Vec<Option<(usize, Signature)>>> {
 
 /// OnchainTxHandler receives claiming requests, aggregates them if it's sound, broadcast and
 /// do RBF bumping if possible.
-pub struct OnchainTxHandler<ChanSigner: ChannelKeys> {
+pub struct OnchainTxHandler<ChannelSigner: Sign> {
        destination_script: Script,
-       local_commitment: Option<LocalCommitmentTransaction>,
-       // local_htlc_sigs and prev_local_htlc_sigs are in the order as they appear in the commitment
+       holder_commitment: HolderCommitmentTransaction,
+       // holder_htlc_sigs and prev_holder_htlc_sigs are in the order as they appear in the commitment
        // transaction outputs (hence the Option<>s inside the Vec). The first usize is the index in
-       // the set of HTLCs in the LocalCommitmentTransaction (including those which do not appear in
-       // the commitment transaction).
-       local_htlc_sigs: Option<Vec<Option<(usize, Signature)>>>,
-       prev_local_commitment: Option<LocalCommitmentTransaction>,
-       prev_local_htlc_sigs: Option<Vec<Option<(usize, Signature)>>>,
-       on_local_tx_csv: u16,
+       // the set of HTLCs in the HolderCommitmentTransaction.
+       holder_htlc_sigs: Option<Vec<Option<(usize, Signature)>>>,
+       prev_holder_commitment: Option<HolderCommitmentTransaction>,
+       prev_holder_htlc_sigs: Option<Vec<Option<(usize, Signature)>>>,
 
-       key_storage: ChanSigner,
+       signer: ChannelSigner,
+       pub(crate) channel_transaction_parameters: ChannelTransactionParameters,
 
        // Used to track claiming requests. If claim tx doesn't confirm before height timer expiration we need to bump
        // it (RBF or CPFP). If an input has been part of an aggregate tx at first claim try, we need to keep it within
@@ -282,20 +282,27 @@ pub struct OnchainTxHandler<ChanSigner: ChannelKeys> {
 
        onchain_events_waiting_threshold_conf: HashMap<u32, Vec<OnchainEvent>>,
 
+       latest_height: u32,
+
        secp_ctx: Secp256k1<secp256k1::All>,
 }
 
-impl<ChanSigner: ChannelKeys + Writeable> OnchainTxHandler<ChanSigner> {
+impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
        pub(crate) fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                self.destination_script.write(writer)?;
-               self.local_commitment.write(writer)?;
-               self.local_htlc_sigs.write(writer)?;
-               self.prev_local_commitment.write(writer)?;
-               self.prev_local_htlc_sigs.write(writer)?;
+               self.holder_commitment.write(writer)?;
+               self.holder_htlc_sigs.write(writer)?;
+               self.prev_holder_commitment.write(writer)?;
+               self.prev_holder_htlc_sigs.write(writer)?;
 
-               self.on_local_tx_csv.write(writer)?;
+               self.channel_transaction_parameters.write(writer)?;
 
-               self.key_storage.write(writer)?;
+               let mut key_data = VecWriter(Vec::new());
+               self.signer.write(&mut key_data)?;
+               assert!(key_data.0.len() < std::usize::MAX);
+               assert!(key_data.0.len() < std::u32::MAX as usize);
+               (key_data.0.len() as u32).write(writer)?;
+               writer.write_all(&key_data.0[..])?;
 
                writer.write_all(&byte_utils::be64_to_array(self.pending_claim_requests.len() as u64))?;
                for (ref ancestor_claim_txid, claim_tx_data) in self.pending_claim_requests.iter() {
@@ -328,22 +335,32 @@ impl<ChanSigner: ChannelKeys + Writeable> OnchainTxHandler<ChanSigner> {
                                }
                        }
                }
+               self.latest_height.write(writer)?;
                Ok(())
        }
 }
 
-impl<ChanSigner: ChannelKeys + Readable> Readable for OnchainTxHandler<ChanSigner> {
-       fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+impl<'a, K: KeysInterface> ReadableArgs<&'a K> for OnchainTxHandler<K::Signer> {
+       fn read<R: ::std::io::Read>(reader: &mut R, keys_manager: &'a K) -> Result<Self, DecodeError> {
                let destination_script = Readable::read(reader)?;
 
-               let local_commitment = Readable::read(reader)?;
-               let local_htlc_sigs = Readable::read(reader)?;
-               let prev_local_commitment = Readable::read(reader)?;
-               let prev_local_htlc_sigs = Readable::read(reader)?;
+               let holder_commitment = Readable::read(reader)?;
+               let holder_htlc_sigs = Readable::read(reader)?;
+               let prev_holder_commitment = Readable::read(reader)?;
+               let prev_holder_htlc_sigs = Readable::read(reader)?;
 
-               let on_local_tx_csv = Readable::read(reader)?;
+               let channel_parameters = Readable::read(reader)?;
 
-               let key_storage = Readable::read(reader)?;
+               let keys_len: u32 = Readable::read(reader)?;
+               let mut keys_data = Vec::with_capacity(cmp::min(keys_len as usize, MAX_ALLOC_SIZE));
+               while keys_data.len() != keys_len as usize {
+                       // Read 1KB at a time to avoid accidentally allocating 4GB on corrupted channel keys
+                       let mut data = [0; 1024];
+                       let read_slice = &mut data[0..cmp::min(1024, keys_len as usize - keys_data.len())];
+                       reader.read_exact(read_slice)?;
+                       keys_data.extend_from_slice(read_slice);
+               }
+               let signer = keys_manager.read_chan_signer(&keys_data)?;
 
                let pending_claim_requests_len: u64 = Readable::read(reader)?;
                let mut pending_claim_requests = HashMap::with_capacity(cmp::min(pending_claim_requests_len as usize, MAX_ALLOC_SIZE / 128));
@@ -387,45 +404,48 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for OnchainTxHandler<ChanSigne
                        }
                        onchain_events_waiting_threshold_conf.insert(height_target, events);
                }
+               let latest_height = Readable::read(reader)?;
+
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
 
                Ok(OnchainTxHandler {
                        destination_script,
-                       local_commitment,
-                       local_htlc_sigs,
-                       prev_local_commitment,
-                       prev_local_htlc_sigs,
-                       on_local_tx_csv,
-                       key_storage,
+                       holder_commitment,
+                       holder_htlc_sigs,
+                       prev_holder_commitment,
+                       prev_holder_htlc_sigs,
+                       signer,
+                       channel_transaction_parameters: channel_parameters,
                        claimable_outpoints,
                        pending_claim_requests,
                        onchain_events_waiting_threshold_conf,
-                       secp_ctx: Secp256k1::new(),
+                       latest_height,
+                       secp_ctx,
                })
        }
 }
 
-impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
-       pub(super) fn new(destination_script: Script, keys: ChanSigner, on_local_tx_csv: u16) -> Self {
-
-               let key_storage = keys;
-
+impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
+       pub(crate) fn new(destination_script: Script, signer: ChannelSigner, channel_parameters: ChannelTransactionParameters, holder_commitment: HolderCommitmentTransaction, secp_ctx: Secp256k1<secp256k1::All>) -> Self {
                OnchainTxHandler {
                        destination_script,
-                       local_commitment: None,
-                       local_htlc_sigs: None,
-                       prev_local_commitment: None,
-                       prev_local_htlc_sigs: None,
-                       on_local_tx_csv,
-                       key_storage,
+                       holder_commitment,
+                       holder_htlc_sigs: None,
+                       prev_holder_commitment: None,
+                       prev_holder_htlc_sigs: None,
+                       signer,
+                       channel_transaction_parameters: channel_parameters,
                        pending_claim_requests: HashMap::new(),
                        claimable_outpoints: HashMap::new(),
                        onchain_events_waiting_threshold_conf: HashMap::new(),
+                       latest_height: 0,
 
-                       secp_ctx: Secp256k1::new(),
+                       secp_ctx,
                }
        }
 
-       pub(super) fn get_witnesses_weight(inputs: &[InputDescriptors]) -> usize {
+       pub(crate) fn get_witnesses_weight(inputs: &[InputDescriptors]) -> usize {
                let mut tx_weight = 2; // count segwit flags
                for inp in inputs {
                        // We use expected weight (and not actual) as signatures and time lock delays may vary
@@ -438,7 +458,7 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                                &InputDescriptors::RevokedReceivedHTLC => {
                                        1 + 1 + 73 + 1 + 33 + 1 + 139
                                },
-                               // number_of_witness_elements + sig_length + remotehtlc_sig  + preimage_length + preimage + witness_script_length + witness_script
+                               // number_of_witness_elements + sig_length + counterpartyhtlc_sig  + preimage_length + preimage + witness_script_length + witness_script
                                &InputDescriptors::OfferedHTLC => {
                                        1 + 1 + 73 + 1 + 32 + 1 + 133
                                },
@@ -471,7 +491,9 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
 
        /// Lightning security model (i.e being able to redeem/timeout HTLC or penalize coutnerparty onchain) lays on the assumption of claim transactions getting confirmed before timelock expiration
        /// (CSV or CLTV following cases). In case of high-fee spikes, claim tx may stuck in the mempool, so you need to bump its feerate quickly using Replace-By-Fee or Child-Pay-For-Parent.
-       fn generate_claim_tx<F: Deref, L: Deref>(&mut self, height: u32, cached_claim_datas: &ClaimTxBumpMaterial, fee_estimator: F, logger: L) -> Option<(Option<u32>, u32, Transaction)>
+       /// Panics if there are signing errors, because signing operations in reaction to on-chain events
+       /// are not expected to fail, and if they do, we may lose funds.
+       fn generate_claim_tx<F: Deref, L: Deref>(&mut self, height: u32, cached_claim_datas: &ClaimTxBumpMaterial, fee_estimator: &F, logger: &L) -> Option<(Option<u32>, u32, Transaction)>
                where F::Target: FeeEstimator,
                                        L::Target: Logger,
        {
@@ -547,11 +569,11 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                                        inputs_witnesses_weight += Self::get_witnesses_weight(&[*input_descriptor]);
                                        amt += *amount;
                                },
-                               &InputMaterial::RemoteHTLC { ref preimage, ref htlc, .. } => {
+                               &InputMaterial::CounterpartyHTLC { ref preimage, ref htlc, .. } => {
                                        inputs_witnesses_weight += Self::get_witnesses_weight(if preimage.is_some() { &[InputDescriptors::OfferedHTLC] } else { &[InputDescriptors::ReceivedHTLC] });
                                        amt += htlc.amount_msat / 1000;
                                },
-                               &InputMaterial::LocalHTLC { .. } => {
+                               &InputMaterial::HolderHTLC { .. } => {
                                        dynamic_fee = false;
                                },
                                &InputMaterial::Funding { .. } => {
@@ -582,47 +604,44 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
 
                        for (i, (outp, per_outp_material)) in cached_claim_datas.per_input_material.iter().enumerate() {
                                match per_outp_material {
-                                       &InputMaterial::Revoked { ref per_commitment_point, ref remote_delayed_payment_base_key, ref remote_htlc_base_key, ref per_commitment_key, ref input_descriptor, ref amount, ref htlc, ref on_remote_tx_csv } => {
-                                               if let Ok(chan_keys) = TxCreationKeys::new(&self.secp_ctx, &per_commitment_point, remote_delayed_payment_base_key, remote_htlc_base_key, &self.key_storage.pubkeys().revocation_basepoint, &self.key_storage.pubkeys().htlc_basepoint) {
+                                       &InputMaterial::Revoked { ref per_commitment_point, ref counterparty_delayed_payment_base_key, ref counterparty_htlc_base_key, ref per_commitment_key, ref input_descriptor, ref amount, ref htlc, ref on_counterparty_tx_csv } => {
+                                               if let Ok(tx_keys) = TxCreationKeys::derive_new(&self.secp_ctx, &per_commitment_point, counterparty_delayed_payment_base_key, counterparty_htlc_base_key, &self.signer.pubkeys().revocation_basepoint, &self.signer.pubkeys().htlc_basepoint) {
 
                                                        let witness_script = if let Some(ref htlc) = *htlc {
-                                                               chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &chan_keys.a_htlc_key, &chan_keys.b_htlc_key, &chan_keys.revocation_key)
+                                                               chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &tx_keys.broadcaster_htlc_key, &tx_keys.countersignatory_htlc_key, &tx_keys.revocation_key)
                                                        } else {
-                                                               chan_utils::get_revokeable_redeemscript(&chan_keys.revocation_key, *on_remote_tx_csv, &chan_keys.a_delayed_payment_key)
+                                                               chan_utils::get_revokeable_redeemscript(&tx_keys.revocation_key, *on_counterparty_tx_csv, &tx_keys.broadcaster_delayed_payment_key)
                                                        };
 
-                                                       if let Ok(sig) = self.key_storage.sign_justice_transaction(&bumped_tx, i, *amount, &per_commitment_key, htlc, &self.secp_ctx) {
-                                                               bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
-                                                               bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
-                                                               if htlc.is_some() {
-                                                                       bumped_tx.input[i].witness.push(chan_keys.revocation_key.clone().serialize().to_vec());
-                                                               } else {
-                                                                       bumped_tx.input[i].witness.push(vec!(1));
-                                                               }
-                                                               bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
-                                                       } else { return None; }
-                                                       //TODO: panic ?
+                                                       let sig = self.signer.sign_justice_transaction(&bumped_tx, i, *amount, &per_commitment_key, htlc, &self.secp_ctx).expect("sign justice tx");
+                                                       bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
+                                                       bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
+                                                       if htlc.is_some() {
+                                                               bumped_tx.input[i].witness.push(tx_keys.revocation_key.clone().serialize().to_vec());
+                                                       } else {
+                                                               bumped_tx.input[i].witness.push(vec!(1));
+                                                       }
+                                                       bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
 
-                                                       log_trace!(logger, "Going to broadcast Penalty Transaction {} claiming revoked {} output {} from {} with new feerate {}...", bumped_tx.txid(), if *input_descriptor == InputDescriptors::RevokedOutput { "to_local" } else if *input_descriptor == InputDescriptors::RevokedOfferedHTLC { "offered" } else if *input_descriptor == InputDescriptors::RevokedReceivedHTLC { "received" } else { "" }, outp.vout, outp.txid, new_feerate);
+                                                       log_trace!(logger, "Going to broadcast Penalty Transaction {} claiming revoked {} output {} from {} with new feerate {}...", bumped_tx.txid(), if *input_descriptor == InputDescriptors::RevokedOutput { "to_holder" } else if *input_descriptor == InputDescriptors::RevokedOfferedHTLC { "offered" } else if *input_descriptor == InputDescriptors::RevokedReceivedHTLC { "received" } else { "" }, outp.vout, outp.txid, new_feerate);
                                                }
                                        },
-                                       &InputMaterial::RemoteHTLC { ref per_commitment_point, ref remote_delayed_payment_base_key, ref remote_htlc_base_key, ref preimage, ref htlc } => {
-                                               if let Ok(chan_keys) = TxCreationKeys::new(&self.secp_ctx, &per_commitment_point, remote_delayed_payment_base_key, remote_htlc_base_key, &self.key_storage.pubkeys().revocation_basepoint, &self.key_storage.pubkeys().htlc_basepoint) {
-                                                       let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &chan_keys.a_htlc_key, &chan_keys.b_htlc_key, &chan_keys.revocation_key);
+                                       &InputMaterial::CounterpartyHTLC { ref per_commitment_point, ref counterparty_delayed_payment_base_key, ref counterparty_htlc_base_key, ref preimage, ref htlc } => {
+                                               if let Ok(tx_keys) = TxCreationKeys::derive_new(&self.secp_ctx, &per_commitment_point, counterparty_delayed_payment_base_key, counterparty_htlc_base_key, &self.signer.pubkeys().revocation_basepoint, &self.signer.pubkeys().htlc_basepoint) {
+                                                       let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &tx_keys.broadcaster_htlc_key, &tx_keys.countersignatory_htlc_key, &tx_keys.revocation_key);
 
                                                        if !preimage.is_some() { bumped_tx.lock_time = htlc.cltv_expiry }; // Right now we don't aggregate time-locked transaction, if we do we should set lock_time before to avoid breaking hash computation
-                                                       if let Ok(sig) = self.key_storage.sign_remote_htlc_transaction(&bumped_tx, i, &htlc.amount_msat / 1000, &per_commitment_point, htlc, &self.secp_ctx) {
-                                                               bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
-                                                               bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
-                                                               if let &Some(preimage) = preimage {
-                                                                       bumped_tx.input[i].witness.push(preimage.0.to_vec());
-                                                               } else {
-                                                                       // Due to BIP146 (MINIMALIF) this must be a zero-length element to relay.
-                                                                       bumped_tx.input[i].witness.push(vec![]);
-                                                               }
-                                                               bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
+                                                       let sig = self.signer.sign_counterparty_htlc_transaction(&bumped_tx, i, &htlc.amount_msat / 1000, &per_commitment_point, htlc, &self.secp_ctx).expect("sign counterparty HTLC tx");
+                                                       bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
+                                                       bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
+                                                       if let &Some(preimage) = preimage {
+                                                               bumped_tx.input[i].witness.push(preimage.0.to_vec());
+                                                       } else {
+                                                               // Due to BIP146 (MINIMALIF) this must be a zero-length element to relay.
+                                                               bumped_tx.input[i].witness.push(vec![]);
                                                        }
-                                                       log_trace!(logger, "Going to broadcast Claim Transaction {} claiming remote {} htlc output {} from {} with new feerate {}...", bumped_tx.txid(), if preimage.is_some() { "offered" } else { "received" }, outp.vout, outp.txid, new_feerate);
+                                                       bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
+                                                       log_trace!(logger, "Going to broadcast Claim Transaction {} claiming counterparty {} htlc output {} from {} with new feerate {}...", bumped_tx.txid(), if preimage.is_some() { "offered" } else { "received" }, outp.vout, outp.txid, new_feerate);
                                                }
                                        },
                                        _ => unreachable!()
@@ -634,21 +653,21 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                } else {
                        for (_, (outp, per_outp_material)) in cached_claim_datas.per_input_material.iter().enumerate() {
                                match per_outp_material {
-                                       &InputMaterial::LocalHTLC { ref preimage, ref amount } => {
+                                       &InputMaterial::HolderHTLC { ref preimage, ref amount } => {
                                                let htlc_tx = self.get_fully_signed_htlc_tx(outp, preimage);
                                                if let Some(htlc_tx) = htlc_tx {
                                                        let feerate = (amount - htlc_tx.output[0].value) * 1000 / htlc_tx.get_weight() as u64;
                                                        // Timer set to $NEVER given we can't bump tx without anchor outputs
-                                                       log_trace!(logger, "Going to broadcast Local HTLC-{} claiming HTLC output {} from {}...", if preimage.is_some() { "Success" } else { "Timeout" }, outp.vout, outp.txid);
+                                                       log_trace!(logger, "Going to broadcast Holder HTLC-{} claiming HTLC output {} from {}...", if preimage.is_some() { "Success" } else { "Timeout" }, outp.vout, outp.txid);
                                                        return Some((None, feerate as u32, htlc_tx));
                                                }
                                                return None;
                                        },
                                        &InputMaterial::Funding { ref funding_redeemscript } => {
-                                               let signed_tx = self.get_fully_signed_local_tx(funding_redeemscript).unwrap();
+                                               let signed_tx = self.get_fully_signed_holder_tx(funding_redeemscript);
                                                // Timer set to $NEVER given we can't bump tx without anchor outputs
-                                               log_trace!(logger, "Going to broadcast Local Transaction {} claiming funding output {} from {}...", signed_tx.txid(), outp.vout, outp.txid);
-                                               return Some((None, self.local_commitment.as_ref().unwrap().feerate_per_kw, signed_tx));
+                                               log_trace!(logger, "Going to broadcast Holder Transaction {} claiming funding output {} from {}...", signed_tx.txid(), outp.vout, outp.txid);
+                                               return Some((None, self.holder_commitment.feerate_per_kw(), signed_tx));
                                        }
                                        _ => unreachable!()
                                }
@@ -657,12 +676,20 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                None
        }
 
-       pub(super) fn block_connected<B: Deref, F: Deref, L: Deref>(&mut self, txn_matched: &[&Transaction], claimable_outpoints: Vec<ClaimRequest>, height: u32, broadcaster: B, fee_estimator: F, logger: L)
+       /// Upon channelmonitor.block_connected(..) or upon provision of a preimage on the forward link
+       /// for this channel, provide new relevant on-chain transactions and/or new claim requests.
+       /// Formerly this was named `block_connected`, but it is now also used for claiming an HTLC output
+       /// if we receive a preimage after force-close.
+       pub(crate) fn update_claims_view<B: Deref, F: Deref, L: Deref>(&mut self, txn_matched: &[&Transaction], claimable_outpoints: Vec<ClaimRequest>, latest_height: Option<u32>, broadcaster: &B, fee_estimator: &F, logger: &L)
                where B::Target: BroadcasterInterface,
                      F::Target: FeeEstimator,
                                        L::Target: Logger,
        {
-               log_trace!(logger, "Block at height {} connected with {} claim requests", height, claimable_outpoints.len());
+               let height = match latest_height {
+                       Some(h) => h,
+                       None => self.latest_height,
+               };
+               log_trace!(logger, "Updating claims view at height {} with {} matched transactions and {} claim requests", height, txn_matched.len(), claimable_outpoints.len());
                let mut new_claims = Vec::new();
                let mut aggregated_claim = HashMap::new();
                let mut aggregated_soonest = ::std::u32::MAX;
@@ -829,7 +856,7 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                }
        }
 
-       pub(super) fn block_disconnected<B: Deref, F: Deref, L: Deref>(&mut self, height: u32, broadcaster: B, fee_estimator: F, logger: L)
+       pub(crate) fn block_disconnected<B: Deref, F: Deref, L: Deref>(&mut self, height: u32, broadcaster: B, fee_estimator: F, logger: L)
                where B::Target: BroadcasterInterface,
                      F::Target: FeeEstimator,
                                        L::Target: Logger,
@@ -855,7 +882,7 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                        }
                }
                for (_, claim_material) in bump_candidates.iter_mut() {
-                       if let Some((new_timer, new_feerate, bump_tx)) = self.generate_claim_tx(height, &claim_material, &*fee_estimator, &*logger) {
+                       if let Some((new_timer, new_feerate, bump_tx)) = self.generate_claim_tx(height, &claim_material, &&*fee_estimator, &&*logger) {
                                claim_material.height_timer = new_timer;
                                claim_material.feerate_previous = new_feerate;
                                broadcaster.broadcast_transaction(&bump_tx);
@@ -877,118 +904,102 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                }
        }
 
-       pub(super) fn provide_latest_local_tx(&mut self, tx: LocalCommitmentTransaction) -> Result<(), ()> {
-               // To prevent any unsafe state discrepancy between offchain and onchain, once local
-               // commitment transaction has been signed due to an event (either block height for
-               // HTLC-timeout or channel force-closure), don't allow any further update of local
-               // commitment transaction view to avoid delivery of revocation secret to counterparty
-               // for the aformentionned signed transaction.
-               if self.local_htlc_sigs.is_some() || self.prev_local_htlc_sigs.is_some() {
-                       return Err(());
-               }
-               self.prev_local_commitment = self.local_commitment.take();
-               self.local_commitment = Some(tx);
-               Ok(())
+       pub(crate) fn provide_latest_holder_tx(&mut self, tx: HolderCommitmentTransaction) {
+               self.prev_holder_commitment = Some(replace(&mut self.holder_commitment, tx));
+               self.holder_htlc_sigs = None;
        }
 
-       fn sign_latest_local_htlcs(&mut self) {
-               if let Some(ref local_commitment) = self.local_commitment {
-                       if let Ok(sigs) = self.key_storage.sign_local_commitment_htlc_transactions(local_commitment, &self.secp_ctx) {
-                               self.local_htlc_sigs = Some(Vec::new());
-                               let ret = self.local_htlc_sigs.as_mut().unwrap();
-                               for (htlc_idx, (local_sig, &(ref htlc, _))) in sigs.iter().zip(local_commitment.per_htlc.iter()).enumerate() {
-                                       if let Some(tx_idx) = htlc.transaction_output_index {
-                                               if ret.len() <= tx_idx as usize { ret.resize(tx_idx as usize + 1, None); }
-                                               ret[tx_idx as usize] = Some((htlc_idx, local_sig.expect("Did not receive a signature for a non-dust HTLC")));
-                                       } else {
-                                               assert!(local_sig.is_none(), "Received a signature for a dust HTLC");
-                                       }
-                               }
-                       }
+       // Normally holder HTLCs are signed at the same time as the holder commitment tx.  However,
+       // in some configurations, the holder commitment tx has been signed and broadcast by a
+       // ChannelMonitor replica, so we handle that case here.
+       fn sign_latest_holder_htlcs(&mut self) {
+               if self.holder_htlc_sigs.is_none() {
+                       let (_sig, sigs) = self.signer.sign_holder_commitment_and_htlcs(&self.holder_commitment, &self.secp_ctx).expect("sign holder commitment");
+                       self.holder_htlc_sigs = Some(Self::extract_holder_sigs(&self.holder_commitment, sigs));
                }
        }
-       fn sign_prev_local_htlcs(&mut self) {
-               if let Some(ref local_commitment) = self.prev_local_commitment {
-                       if let Ok(sigs) = self.key_storage.sign_local_commitment_htlc_transactions(local_commitment, &self.secp_ctx) {
-                               self.prev_local_htlc_sigs = Some(Vec::new());
-                               let ret = self.prev_local_htlc_sigs.as_mut().unwrap();
-                               for (htlc_idx, (local_sig, &(ref htlc, _))) in sigs.iter().zip(local_commitment.per_htlc.iter()).enumerate() {
-                                       if let Some(tx_idx) = htlc.transaction_output_index {
-                                               if ret.len() <= tx_idx as usize { ret.resize(tx_idx as usize + 1, None); }
-                                               ret[tx_idx as usize] = Some((htlc_idx, local_sig.expect("Did not receive a signature for a non-dust HTLC")));
-                                       } else {
-                                               assert!(local_sig.is_none(), "Received a signature for a dust HTLC");
-                                       }
-                               }
+
+       // Normally only the latest commitment tx and HTLCs need to be signed.  However, in some
+       // configurations we may have updated our holder commitment but a replica of the ChannelMonitor
+       // broadcast the previous one before we sync with it.  We handle that case here.
+       fn sign_prev_holder_htlcs(&mut self) {
+               if self.prev_holder_htlc_sigs.is_none() {
+                       if let Some(ref holder_commitment) = self.prev_holder_commitment {
+                               let (_sig, sigs) = self.signer.sign_holder_commitment_and_htlcs(holder_commitment, &self.secp_ctx).expect("sign previous holder commitment");
+                               self.prev_holder_htlc_sigs = Some(Self::extract_holder_sigs(holder_commitment, sigs));
                        }
                }
        }
 
-       //TODO: getting lastest local transactions should be infaillible and result in us "force-closing the channel", but we may
-       // have empty local commitment transaction if a ChannelMonitor is asked to force-close just after Channel::get_outbound_funding_created,
+       fn extract_holder_sigs(holder_commitment: &HolderCommitmentTransaction, sigs: Vec<Signature>) -> Vec<Option<(usize, Signature)>> {
+               let mut ret = Vec::new();
+               for (htlc_idx, (holder_sig, htlc)) in sigs.iter().zip(holder_commitment.htlcs().iter()).enumerate() {
+                       let tx_idx = htlc.transaction_output_index.unwrap();
+                       if ret.len() <= tx_idx as usize { ret.resize(tx_idx as usize + 1, None); }
+                       ret[tx_idx as usize] = Some((htlc_idx, holder_sig.clone()));
+               }
+               ret
+       }
+
+       //TODO: getting lastest holder transactions should be infallible and result in us "force-closing the channel", but we may
+       // have empty holder commitment transaction if a ChannelMonitor is asked to force-close just after Channel::get_outbound_funding_created,
        // before providing a initial commitment transaction. For outbound channel, init ChannelMonitor at Channel::funding_signed, there is nothing
        // to monitor before.
-       pub(super) fn get_fully_signed_local_tx(&mut self, funding_redeemscript: &Script) -> Option<Transaction> {
-               if let Some(ref mut local_commitment) = self.local_commitment {
-                       match self.key_storage.sign_local_commitment(local_commitment, &self.secp_ctx) {
-                               Ok(sig) => Some(local_commitment.add_local_sig(funding_redeemscript, sig)),
-                               Err(_) => return None,
-                       }
-               } else {
-                       None
-               }
+       pub(crate) fn get_fully_signed_holder_tx(&mut self, funding_redeemscript: &Script) -> Transaction {
+               let (sig, htlc_sigs) = self.signer.sign_holder_commitment_and_htlcs(&self.holder_commitment, &self.secp_ctx).expect("signing holder commitment");
+               self.holder_htlc_sigs = Some(Self::extract_holder_sigs(&self.holder_commitment, htlc_sigs));
+               self.holder_commitment.add_holder_sig(funding_redeemscript, sig)
        }
 
-       #[cfg(test)]
-       pub(super) fn get_fully_signed_copy_local_tx(&mut self, funding_redeemscript: &Script) -> Option<Transaction> {
-               if let Some(ref mut local_commitment) = self.local_commitment {
-                       let local_commitment = local_commitment.clone();
-                       match self.key_storage.sign_local_commitment(&local_commitment, &self.secp_ctx) {
-                               Ok(sig) => Some(local_commitment.add_local_sig(funding_redeemscript, sig)),
-                               Err(_) => return None,
-                       }
-               } else {
-                       None
-               }
+       #[cfg(any(test, feature="unsafe_revoked_tx_signing"))]
+       pub(crate) fn get_fully_signed_copy_holder_tx(&mut self, funding_redeemscript: &Script) -> Transaction {
+               let (sig, htlc_sigs) = self.signer.unsafe_sign_holder_commitment_and_htlcs(&self.holder_commitment, &self.secp_ctx).expect("sign holder commitment");
+               self.holder_htlc_sigs = Some(Self::extract_holder_sigs(&self.holder_commitment, htlc_sigs));
+               self.holder_commitment.add_holder_sig(funding_redeemscript, sig)
        }
 
-       pub(super) fn get_fully_signed_htlc_tx(&mut self, outp: &::bitcoin::OutPoint, preimage: &Option<PaymentPreimage>) -> Option<Transaction> {
+       pub(crate) fn get_fully_signed_htlc_tx(&mut self, outp: &::bitcoin::OutPoint, preimage: &Option<PaymentPreimage>) -> Option<Transaction> {
                let mut htlc_tx = None;
-               if self.local_commitment.is_some() {
-                       let commitment_txid = self.local_commitment.as_ref().unwrap().txid();
-                       if commitment_txid == outp.txid {
-                               self.sign_latest_local_htlcs();
-                               if let &Some(ref htlc_sigs) = &self.local_htlc_sigs {
-                                       let &(ref htlc_idx, ref htlc_sig) = htlc_sigs[outp.vout as usize].as_ref().unwrap();
-                                       htlc_tx = Some(self.local_commitment.as_ref().unwrap()
-                                               .get_signed_htlc_tx(*htlc_idx, htlc_sig, preimage, self.on_local_tx_csv));
-                               }
+               let commitment_txid = self.holder_commitment.trust().txid();
+               // Check if the HTLC spends from the current holder commitment
+               if commitment_txid == outp.txid {
+                       self.sign_latest_holder_htlcs();
+                       if let &Some(ref htlc_sigs) = &self.holder_htlc_sigs {
+                               let &(ref htlc_idx, ref htlc_sig) = htlc_sigs[outp.vout as usize].as_ref().unwrap();
+                               let trusted_tx = self.holder_commitment.trust();
+                               let counterparty_htlc_sig = self.holder_commitment.counterparty_htlc_sigs[*htlc_idx];
+                               htlc_tx = Some(trusted_tx
+                                       .get_signed_htlc_tx(&self.channel_transaction_parameters.as_holder_broadcastable(), *htlc_idx, &counterparty_htlc_sig, htlc_sig, preimage));
                        }
                }
-               if self.prev_local_commitment.is_some() {
-                       let commitment_txid = self.prev_local_commitment.as_ref().unwrap().txid();
+               // If the HTLC doesn't spend the current holder commitment, check if it spends the previous one
+               if htlc_tx.is_none() && self.prev_holder_commitment.is_some() {
+                       let commitment_txid = self.prev_holder_commitment.as_ref().unwrap().trust().txid();
                        if commitment_txid == outp.txid {
-                               self.sign_prev_local_htlcs();
-                               if let &Some(ref htlc_sigs) = &self.prev_local_htlc_sigs {
+                               self.sign_prev_holder_htlcs();
+                               if let &Some(ref htlc_sigs) = &self.prev_holder_htlc_sigs {
                                        let &(ref htlc_idx, ref htlc_sig) = htlc_sigs[outp.vout as usize].as_ref().unwrap();
-                                       htlc_tx = Some(self.prev_local_commitment.as_ref().unwrap()
-                                               .get_signed_htlc_tx(*htlc_idx, htlc_sig, preimage, self.on_local_tx_csv));
+                                       let holder_commitment = self.prev_holder_commitment.as_ref().unwrap();
+                                       let trusted_tx = holder_commitment.trust();
+                                       let counterparty_htlc_sig = holder_commitment.counterparty_htlc_sigs[*htlc_idx];
+                                       htlc_tx = Some(trusted_tx
+                                               .get_signed_htlc_tx(&self.channel_transaction_parameters.as_holder_broadcastable(), *htlc_idx, &counterparty_htlc_sig, htlc_sig, preimage));
                                }
                        }
                }
                htlc_tx
        }
 
-       #[cfg(test)]
-       pub(super) fn unsafe_get_fully_signed_htlc_tx(&mut self, outp: &::bitcoin::OutPoint, preimage: &Option<PaymentPreimage>) -> Option<Transaction> {
-               let latest_had_sigs = self.local_htlc_sigs.is_some();
-               let prev_had_sigs = self.prev_local_htlc_sigs.is_some();
+       #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
+       pub(crate) fn unsafe_get_fully_signed_htlc_tx(&mut self, outp: &::bitcoin::OutPoint, preimage: &Option<PaymentPreimage>) -> Option<Transaction> {
+               let latest_had_sigs = self.holder_htlc_sigs.is_some();
+               let prev_had_sigs = self.prev_holder_htlc_sigs.is_some();
                let ret = self.get_fully_signed_htlc_tx(outp, preimage);
                if !latest_had_sigs {
-                       self.local_htlc_sigs = None;
+                       self.holder_htlc_sigs = None;
                }
                if !prev_had_sigs {
-                       self.prev_local_htlc_sigs = None;
+                       self.prev_holder_htlc_sigs = None;
                }
                ret
        }