Merge pull request #1828 from lightning-signer/2022-11-non-zero-fee-anchors
[rust-lightning] / lightning / src / ln / chan_utils.rs
index 370c0cc8edfe6737f3f1d65f5dab59ea688ee854..3a6e81e6399c804bed7fac94a8526ddef809e7df 100644 (file)
 
 use bitcoin::blockdata::script::{Script,Builder};
 use bitcoin::blockdata::opcodes;
-use bitcoin::blockdata::transaction::{TxIn,TxOut,OutPoint,Transaction, SigHashType};
-use bitcoin::util::bip143;
+use bitcoin::blockdata::transaction::{TxIn,TxOut,OutPoint,Transaction, EcdsaSighashType};
+use bitcoin::util::sighash;
 
 use bitcoin::hashes::{Hash, HashEngine};
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hashes::ripemd160::Hash as Ripemd160;
 use bitcoin::hash_types::{Txid, PubkeyHash};
 
-use ln::{PaymentHash, PaymentPreimage};
-use ln::msgs::DecodeError;
-use util::ser::{Readable, Writeable, Writer};
-use util::{byte_utils, transaction_utils};
+use crate::ln::{PaymentHash, PaymentPreimage};
+use crate::ln::msgs::DecodeError;
+use crate::util::ser::{Readable, Writeable, Writer};
+use crate::util::{byte_utils, transaction_utils};
 
 use bitcoin::hash_types::WPubkeyHash;
-use bitcoin::secp256k1::key::{SecretKey, PublicKey};
-use bitcoin::secp256k1::{Secp256k1, Signature, Message};
+use bitcoin::secp256k1::{SecretKey, PublicKey, Scalar};
+use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature, Message};
 use bitcoin::secp256k1::Error as SecpError;
-use bitcoin::secp256k1;
+use bitcoin::{PackedLockTime, secp256k1, Sequence, Witness};
 
-use io;
-use prelude::*;
+use crate::io;
+use crate::prelude::*;
 use core::cmp;
-use ln::chan_utils;
-use util::transaction_utils::sort_outputs;
-use ln::channel::{INITIAL_COMMITMENT_NUMBER, ANCHOR_OUTPUT_VALUE_SATOSHI};
+use crate::ln::chan_utils;
+use crate::util::transaction_utils::sort_outputs;
+use crate::ln::channel::{INITIAL_COMMITMENT_NUMBER, ANCHOR_OUTPUT_VALUE_SATOSHI};
 use core::ops::Deref;
-use chain;
-use util::crypto::sign;
+use crate::chain;
+use crate::util::crypto::sign;
 
 pub(crate) const MAX_HTLCS: u16 = 483;
+pub(crate) const OFFERED_HTLC_SCRIPT_WEIGHT: usize = 133;
+pub(crate) const OFFERED_HTLC_SCRIPT_WEIGHT_ANCHORS: usize = 136;
+// The weight of `accepted_htlc_script` can vary in function of its CLTV argument value. We define a
+// range that encompasses both its non-anchors and anchors variants.
+pub(crate) const MIN_ACCEPTED_HTLC_SCRIPT_WEIGHT: usize = 136;
+pub(crate) const MAX_ACCEPTED_HTLC_SCRIPT_WEIGHT: usize = 143;
 
 /// Gets the weight for an HTLC-Success transaction.
 #[inline]
@@ -59,19 +65,73 @@ pub fn htlc_timeout_tx_weight(opt_anchors: bool) -> u64 {
        if opt_anchors { HTLC_TIMEOUT_ANCHOR_TX_WEIGHT } else { HTLC_TIMEOUT_TX_WEIGHT }
 }
 
-#[derive(PartialEq)]
-pub(crate) enum HTLCType {
-       AcceptedHTLC,
-       OfferedHTLC
+#[derive(PartialEq, Eq)]
+pub(crate) enum HTLCClaim {
+       OfferedTimeout,
+       OfferedPreimage,
+       AcceptedTimeout,
+       AcceptedPreimage,
+       Revocation,
 }
 
-impl HTLCType {
-       /// Check if a given tx witnessScript len matchs one of a pre-signed HTLC
-       pub(crate) fn scriptlen_to_htlctype(witness_script_len: usize) ->  Option<HTLCType> {
-               if witness_script_len == 133 {
-                       Some(HTLCType::OfferedHTLC)
-               } else if witness_script_len >= 136 && witness_script_len <= 139 {
-                       Some(HTLCType::AcceptedHTLC)
+impl HTLCClaim {
+       /// Check if a given input witness attempts to claim a HTLC.
+       pub(crate) fn from_witness(witness: &Witness) -> Option<Self> {
+               debug_assert_eq!(OFFERED_HTLC_SCRIPT_WEIGHT_ANCHORS, MIN_ACCEPTED_HTLC_SCRIPT_WEIGHT);
+               if witness.len() < 2 {
+                       return None;
+               }
+               let witness_script = witness.last().unwrap();
+               let second_to_last = witness.second_to_last().unwrap();
+               if witness_script.len() == OFFERED_HTLC_SCRIPT_WEIGHT {
+                       if witness.len() == 3 && second_to_last.len() == 33 {
+                               // <revocation sig> <revocationpubkey> <witness_script>
+                               Some(Self::Revocation)
+                       } else if witness.len() == 3 && second_to_last.len() == 32 {
+                               // <remotehtlcsig> <payment_preimage> <witness_script>
+                               Some(Self::OfferedPreimage)
+                       } else if witness.len() == 5 && second_to_last.len() == 0 {
+                               // 0 <remotehtlcsig> <localhtlcsig> <> <witness_script>
+                               Some(Self::OfferedTimeout)
+                       } else {
+                               None
+                       }
+               } else if witness_script.len() == OFFERED_HTLC_SCRIPT_WEIGHT_ANCHORS {
+                       // It's possible for the weight of `offered_htlc_script` and `accepted_htlc_script` to
+                       // match so we check for both here.
+                       if witness.len() == 3 && second_to_last.len() == 33 {
+                               // <revocation sig> <revocationpubkey> <witness_script>
+                               Some(Self::Revocation)
+                       } else if witness.len() == 3 && second_to_last.len() == 32 {
+                               // <remotehtlcsig> <payment_preimage> <witness_script>
+                               Some(Self::OfferedPreimage)
+                       } else if witness.len() == 5 && second_to_last.len() == 0 {
+                               // 0 <remotehtlcsig> <localhtlcsig> <> <witness_script>
+                               Some(Self::OfferedTimeout)
+                       } else if witness.len() == 3 && second_to_last.len() == 0 {
+                               // <remotehtlcsig> <> <witness_script>
+                               Some(Self::AcceptedTimeout)
+                       } else if witness.len() == 5 && second_to_last.len() == 32 {
+                               // 0 <remotehtlcsig> <localhtlcsig> <payment_preimage> <witness_script>
+                               Some(Self::AcceptedPreimage)
+                       } else {
+                               None
+                       }
+               } else if witness_script.len() > MIN_ACCEPTED_HTLC_SCRIPT_WEIGHT &&
+                       witness_script.len() <= MAX_ACCEPTED_HTLC_SCRIPT_WEIGHT {
+                       // Handle remaining range of ACCEPTED_HTLC_SCRIPT_WEIGHT.
+                       if witness.len() == 3 && second_to_last.len() == 33 {
+                               // <revocation sig> <revocationpubkey> <witness_script>
+                               Some(Self::Revocation)
+                       } else if witness.len() == 3 && second_to_last.len() == 0 {
+                               // <remotehtlcsig> <> <witness_script>
+                               Some(Self::AcceptedTimeout)
+                       } else if witness.len() == 5 && second_to_last.len() == 32 {
+                               // 0 <remotehtlcsig> <localhtlcsig> <payment_preimage> <witness_script>
+                               Some(Self::AcceptedPreimage)
+                       } else {
+                               None
+                       }
                } else {
                        None
                }
@@ -101,8 +161,8 @@ pub fn build_closing_transaction(to_holder_value_sat: u64, to_counterparty_value
                ins.push(TxIn {
                        previous_output: funding_outpoint,
                        script_sig: Script::new(),
-                       sequence: 0xffffffff,
-                       witness: Vec::new(),
+                       sequence: Sequence::MAX,
+                       witness: Witness::new(),
                });
                ins
        };
@@ -132,14 +192,14 @@ pub fn build_closing_transaction(to_holder_value_sat: u64, to_counterparty_value
 
        Transaction {
                version: 2,
-               lock_time: 0,
+               lock_time: PackedLockTime::ZERO,
                input: txins,
                output: outputs,
        }
 }
 
 /// Implements the per-commitment secret storage scheme from
-/// [BOLT 3](https://github.com/lightningnetwork/lightning-rfc/blob/dcbf8583976df087c79c3ce0b535311212e6812d/03-transactions.md#efficient-per-commitment-secret-storage).
+/// [BOLT 3](https://github.com/lightning/bolts/blob/dcbf8583976df087c79c3ce0b535311212e6812d/03-transactions.md#efficient-per-commitment-secret-storage).
 ///
 /// Allows us to keep track of all of the revocation secrets of our counterparty in just 50*32 bytes
 /// or so.
@@ -148,6 +208,7 @@ pub struct CounterpartyCommitmentSecrets {
        old_secrets: [([u8; 32], u64); 49],
 }
 
+impl Eq for CounterpartyCommitmentSecrets {}
 impl PartialEq for CounterpartyCommitmentSecrets {
        fn eq(&self, other: &Self) -> bool {
                for (&(ref secret, ref idx), &(ref o_secret, ref o_idx)) in self.old_secrets.iter().zip(other.old_secrets.iter()) {
@@ -264,9 +325,7 @@ pub fn derive_private_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_co
        sha.input(&PublicKey::from_secret_key(&secp_ctx, &base_secret).serialize());
        let res = Sha256::from_engine(sha).into_inner();
 
-       let mut key = base_secret.clone();
-       key.add_assign(&res)?;
-       Ok(key)
+       base_secret.clone().add_tweak(&Scalar::from_be_bytes(res).unwrap())
 }
 
 /// Derives a per-commitment-transaction public key (eg an htlc key or a delayed_payment key)
@@ -287,7 +346,7 @@ pub fn derive_public_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_com
 
 /// Derives a per-commitment-transaction revocation key from its constituent parts.
 ///
-/// Only the cheating participant owns a valid witness to propagate a revoked 
+/// Only the cheating participant owns a valid witness to propagate a revoked
 /// commitment transaction, thus per_commitment_secret always come from cheater
 /// and revocation_base_secret always come from punisher, which is the broadcaster
 /// of the transaction spending with this key knowledge.
@@ -313,19 +372,16 @@ pub fn derive_private_revocation_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1
                Sha256::from_engine(sha).into_inner()
        };
 
-       let mut countersignatory_contrib = countersignatory_revocation_base_secret.clone();
-       countersignatory_contrib.mul_assign(&rev_append_commit_hash_key)?;
-       let mut broadcaster_contrib = per_commitment_secret.clone();
-       broadcaster_contrib.mul_assign(&commit_append_rev_hash_key)?;
-       countersignatory_contrib.add_assign(&broadcaster_contrib[..])?;
-       Ok(countersignatory_contrib)
+       let countersignatory_contrib = countersignatory_revocation_base_secret.clone().mul_tweak(&Scalar::from_be_bytes(rev_append_commit_hash_key).unwrap())?;
+       let broadcaster_contrib = per_commitment_secret.clone().mul_tweak(&Scalar::from_be_bytes(commit_append_rev_hash_key).unwrap())?;
+       countersignatory_contrib.add_tweak(&Scalar::from_be_bytes(broadcaster_contrib.secret_bytes()).unwrap())
 }
 
 /// Derives a per-commitment-transaction revocation public key from its constituent parts. This is
 /// the public equivalend of derive_private_revocation_key - using only public keys to derive a
 /// public key instead of private keys.
 ///
-/// Only the cheating participant owns a valid witness to propagate a revoked 
+/// Only the cheating participant owns a valid witness to propagate a revoked
 /// commitment transaction, thus per_commitment_point always come from cheater
 /// and revocation_base_point always come from punisher, which is the broadcaster
 /// of the transaction spending with this key knowledge.
@@ -348,10 +404,8 @@ pub fn derive_public_revocation_key<T: secp256k1::Verification>(secp_ctx: &Secp2
                Sha256::from_engine(sha).into_inner()
        };
 
-       let mut countersignatory_contrib = countersignatory_revocation_base_point.clone();
-       countersignatory_contrib.mul_assign(&secp_ctx, &rev_append_commit_hash_key)?;
-       let mut broadcaster_contrib = per_commitment_point.clone();
-       broadcaster_contrib.mul_assign(&secp_ctx, &commit_append_rev_hash_key)?;
+       let countersignatory_contrib = countersignatory_revocation_base_point.clone().mul_tweak(&secp_ctx, &Scalar::from_be_bytes(rev_append_commit_hash_key).unwrap())?;
+       let broadcaster_contrib = per_commitment_point.clone().mul_tweak(&secp_ctx, &Scalar::from_be_bytes(commit_append_rev_hash_key).unwrap())?;
        countersignatory_contrib.combine(&broadcaster_contrib)
 }
 
@@ -366,7 +420,7 @@ pub fn derive_public_revocation_key<T: secp256k1::Verification>(secp_ctx: &Secp2
 /// channel basepoints via the new function, or they were obtained via
 /// CommitmentTransaction.trust().keys() because we trusted the source of the
 /// pre-calculated keys.
-#[derive(PartialEq, Clone)]
+#[derive(PartialEq, Eq, Clone)]
 pub struct TxCreationKeys {
        /// The broadcaster's per-commitment public key which was used to derive the other keys.
        pub per_commitment_point: PublicKey,
@@ -391,7 +445,7 @@ impl_writeable_tlv_based!(TxCreationKeys, {
 });
 
 /// One counterparty's public keys which do not change over the life of a channel.
-#[derive(Clone, PartialEq)]
+#[derive(Clone, PartialEq, Eq)]
 pub struct ChannelPublicKeys {
        /// The public key which is used to sign all commitment transactions, as it appears in the
        /// on-chain channel lock-in 2-of-2 multisig output.
@@ -472,8 +526,8 @@ pub fn get_revokeable_redeemscript(revocation_key: &PublicKey, contest_delay: u1
        res
 }
 
-#[derive(Clone, PartialEq)]
 /// Information about an HTLC as it appears in a commitment transaction
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct HTLCOutputInCommitment {
        /// Whether the HTLC was "offered" (ie outbound in relation to this commitment transaction).
        /// Note that this is not the same as whether it is ountbound *from us*. To determine that you
@@ -606,7 +660,7 @@ pub fn make_funding_redeemscript(broadcaster: &PublicKey, countersignatory: &Pub
 ///
 /// Panics if htlc.transaction_output_index.is_none() (as such HTLCs do not appear in the
 /// commitment transaction).
-pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, contest_delay: u16, htlc: &HTLCOutputInCommitment, opt_anchors: bool, broadcaster_delayed_payment_key: &PublicKey, revocation_key: &PublicKey) -> Transaction {
+pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, contest_delay: u16, htlc: &HTLCOutputInCommitment, opt_anchors: bool, use_non_zero_fee_anchors: bool, broadcaster_delayed_payment_key: &PublicKey, revocation_key: &PublicKey) -> Transaction {
        let mut txins: Vec<TxIn> = Vec::new();
        txins.push(TxIn {
                previous_output: OutPoint {
@@ -614,8 +668,8 @@ pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, conte
                        vout: htlc.transaction_output_index.expect("Can't build an HTLC transaction for a dust output"),
                },
                script_sig: Script::new(),
-               sequence: if opt_anchors { 1 } else { 0 },
-               witness: Vec::new(),
+               sequence: Sequence(if opt_anchors { 1 } else { 0 }),
+               witness: Witness::new(),
        });
 
        let weight = if htlc.offered {
@@ -623,17 +677,22 @@ pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, conte
        } else {
                htlc_success_tx_weight(opt_anchors)
        };
-       let total_fee = feerate_per_kw as u64 * weight / 1000;
+       let output_value = if opt_anchors && !use_non_zero_fee_anchors {
+               htlc.amount_msat / 1000
+       } else {
+               let total_fee = feerate_per_kw as u64 * weight / 1000;
+               htlc.amount_msat / 1000 - total_fee
+       };
 
        let mut txouts: Vec<TxOut> = Vec::new();
        txouts.push(TxOut {
                script_pubkey: get_revokeable_redeemscript(revocation_key, contest_delay, broadcaster_delayed_payment_key).to_v0_p2wsh(),
-               value: htlc.amount_msat / 1000 - total_fee //TODO: BOLT 3 does not specify if we should add amount_msat before dividing or if we should divide by 1000 before subtracting (as we do here)
+               value: output_value,
        });
 
        Transaction {
                version: 2,
-               lock_time: if htlc.offered { htlc.cltv_expiry } else { 0 },
+               lock_time: PackedLockTime(if htlc.offered { htlc.cltv_expiry } else { 0 }),
                input: txins,
                output: txouts,
        }
@@ -668,6 +727,23 @@ pub fn get_anchor_redeemscript(funding_pubkey: &PublicKey) -> Script {
                .into_script()
 }
 
+#[cfg(anchors)]
+/// Locates the output with an anchor script paying to `funding_pubkey` within `commitment_tx`.
+pub(crate) fn get_anchor_output<'a>(commitment_tx: &'a Transaction, funding_pubkey: &PublicKey) -> Option<(u32, &'a TxOut)> {
+       let anchor_script = chan_utils::get_anchor_redeemscript(funding_pubkey).to_v0_p2wsh();
+       commitment_tx.output.iter().enumerate()
+               .find(|(_, txout)| txout.script_pubkey == anchor_script)
+               .map(|(idx, txout)| (idx as u32, txout))
+}
+
+/// Returns the witness required to satisfy and spend an anchor input.
+pub fn build_anchor_input_witness(funding_key: &PublicKey, funding_sig: &Signature) -> Witness {
+       let anchor_redeem_script = chan_utils::get_anchor_redeemscript(funding_key);
+       let mut funding_sig = funding_sig.serialize_der().to_vec();
+       funding_sig.push(EcdsaSighashType::All as u8);
+       Witness::from_vec(vec![funding_sig, anchor_redeem_script.to_bytes()])
+}
+
 /// Per-channel data used to build transactions in conjunction with the per-commitment data (CommitmentTransaction).
 /// The fields are organized by holder/counterparty.
 ///
@@ -687,8 +763,13 @@ pub struct ChannelTransactionParameters {
        pub counterparty_parameters: Option<CounterpartyChannelTransactionParameters>,
        /// The late-bound funding outpoint
        pub funding_outpoint: Option<chain::transaction::OutPoint>,
-       /// Are anchors used for this channel.  Boolean is serialization backwards-compatible
-       pub opt_anchors: Option<()>
+       /// Are anchors (zero fee HTLC transaction variant) used for this channel. Boolean is
+       /// serialization backwards-compatible.
+       pub opt_anchors: Option<()>,
+       /// Are non-zero-fee anchors are enabled (used in conjuction with opt_anchors)
+       /// It is intended merely for backwards compatibility with signers that need it.
+       /// There is no support for this feature in LDK channel negotiation.
+       pub opt_non_zero_fee_anchors: Option<()>,
 }
 
 /// Late-bound per-channel counterparty data used to build transactions.
@@ -743,6 +824,7 @@ impl_writeable_tlv_based!(ChannelTransactionParameters, {
        (6, counterparty_parameters, option),
        (8, funding_outpoint, option),
        (10, opt_anchors, option),
+       (12, opt_non_zero_fee_anchors, option),
 });
 
 /// Static channel fields used to build transactions given per-commitment fields, organized by
@@ -823,6 +905,7 @@ impl Deref for HolderCommitmentTransaction {
        fn deref(&self) -> &Self::Target { &self.inner }
 }
 
+impl Eq for HolderCommitmentTransaction {}
 impl PartialEq for HolderCommitmentTransaction {
        // We dont care whether we are signed in equality comparison
        fn eq(&self, o: &Self) -> bool {
@@ -863,8 +946,9 @@ impl HolderCommitmentTransaction {
                        holder_selected_contest_delay: 0,
                        is_outbound_from_holder: false,
                        counterparty_parameters: Some(CounterpartyChannelTransactionParameters { pubkeys: channel_pubkeys.clone(), selected_contest_delay: 0 }),
-                       funding_outpoint: Some(chain::transaction::OutPoint { txid: Default::default(), index: 0 }),
-                       opt_anchors: None
+                       funding_outpoint: Some(chain::transaction::OutPoint { txid: Txid::all_zeros(), index: 0 }),
+                       opt_anchors: None,
+                       opt_non_zero_fee_anchors: None,
                };
                let mut htlcs_with_aux: Vec<(_, ())> = Vec::new();
                let inner = CommitmentTransaction::new_with_auxiliary_htlc_data(0, 0, 0, false, dummy_key.clone(), dummy_key.clone(), keys, 0, &mut htlcs_with_aux, &channel_parameters.as_counterparty_broadcastable());
@@ -891,16 +975,18 @@ impl HolderCommitmentTransaction {
                // First push the multisig dummy, note that due to BIP147 (NULLDUMMY) it must be a zero-length element.
                let mut tx = self.inner.built.transaction.clone();
                tx.input[0].witness.push(Vec::new());
+               let mut ser_holder_sig = holder_sig.serialize_der().to_vec();
+               ser_holder_sig.push(EcdsaSighashType::All as u8);
+               let mut ser_cp_sig = self.counterparty_sig.serialize_der().to_vec();
+               ser_cp_sig.push(EcdsaSighashType::All as u8);
 
                if self.holder_sig_first {
-                       tx.input[0].witness.push(holder_sig.serialize_der().to_vec());
-                       tx.input[0].witness.push(self.counterparty_sig.serialize_der().to_vec());
+                       tx.input[0].witness.push(ser_holder_sig);
+                       tx.input[0].witness.push(ser_cp_sig);
                } else {
-                       tx.input[0].witness.push(self.counterparty_sig.serialize_der().to_vec());
-                       tx.input[0].witness.push(holder_sig.serialize_der().to_vec());
+                       tx.input[0].witness.push(ser_cp_sig);
+                       tx.input[0].witness.push(ser_holder_sig);
                }
-               tx.input[0].witness[1].push(SigHashType::All as u8);
-               tx.input[0].witness[2].push(SigHashType::All as u8);
 
                tx.input[0].witness.push(funding_redeemscript.as_bytes().to_vec());
                tx
@@ -929,7 +1015,7 @@ impl BuiltCommitmentTransaction {
        ///
        /// This can be used to verify a signature.
        pub fn get_sighash_all(&self, funding_redeemscript: &Script, channel_value_satoshis: u64) -> Message {
-               let sighash = &bip143::SigHashCache::new(&self.transaction).signature_hash(0, funding_redeemscript, channel_value_satoshis, SigHashType::All)[..];
+               let sighash = &sighash::SighashCache::new(&self.transaction).segwit_signature_hash(0, funding_redeemscript, channel_value_satoshis, EcdsaSighashType::All).unwrap()[..];
                hash_to_message!(sighash)
        }
 
@@ -946,7 +1032,7 @@ impl BuiltCommitmentTransaction {
 ///
 /// This class can be used inside a signer implementation to generate a signature given the relevant
 /// secret key.
-#[derive(Clone, Hash, PartialEq)]
+#[derive(Clone, Hash, PartialEq, Eq)]
 pub struct ClosingTransaction {
        to_holder_value_sat: u64,
        to_counterparty_value_sat: u64,
@@ -1053,7 +1139,7 @@ impl<'a> TrustedClosingTransaction<'a> {
        ///
        /// This can be used to verify a signature.
        pub fn get_sighash_all(&self, funding_redeemscript: &Script, channel_value_satoshis: u64) -> Message {
-               let sighash = &bip143::SigHashCache::new(&self.inner.built).signature_hash(0, funding_redeemscript, channel_value_satoshis, SigHashType::All)[..];
+               let sighash = &sighash::SighashCache::new(&self.inner.built).segwit_signature_hash(0, funding_redeemscript, channel_value_satoshis, EcdsaSighashType::All).unwrap()[..];
                hash_to_message!(sighash)
        }
 
@@ -1080,12 +1166,15 @@ pub struct CommitmentTransaction {
        htlcs: Vec<HTLCOutputInCommitment>,
        // A boolean that is serialization backwards-compatible
        opt_anchors: Option<()>,
+       // Whether non-zero-fee anchors should be used
+       opt_non_zero_fee_anchors: Option<()>,
        // A cache of the parties' pubkeys required to construct the transaction, see doc for trust()
        keys: TxCreationKeys,
        // For access to the pre-built transaction, see doc for trust()
        built: BuiltCommitmentTransaction,
 }
 
+impl Eq for CommitmentTransaction {}
 impl PartialEq for CommitmentTransaction {
        fn eq(&self, o: &Self) -> bool {
                let eq = self.commitment_number == o.commitment_number &&
@@ -1112,6 +1201,7 @@ impl_writeable_tlv_based!(CommitmentTransaction, {
        (10, built, required),
        (12, htlcs, vec_type),
        (14, opt_anchors, option),
+       (16, opt_non_zero_fee_anchors, option),
 });
 
 impl CommitmentTransaction {
@@ -1144,9 +1234,18 @@ impl CommitmentTransaction {
                                transaction,
                                txid
                        },
+                       opt_non_zero_fee_anchors: None,
                }
        }
 
+       /// Use non-zero fee anchors
+       ///
+       /// (C-not exported) due to move, and also not likely to be useful for binding users
+       pub fn with_non_zero_fee_anchors(mut self) -> Self {
+               self.opt_non_zero_fee_anchors = Some(());
+               self
+       }
+
        fn internal_rebuild_transaction(&self, keys: &TxCreationKeys, channel_parameters: &DirectedChannelTransactionParameters, broadcaster_funding_key: &PublicKey, countersignatory_funding_key: &PublicKey) -> Result<BuiltCommitmentTransaction, ()> {
                let (obscured_commitment_transaction_number, txins) = Self::internal_build_inputs(self.commitment_number, channel_parameters);
 
@@ -1165,7 +1264,7 @@ impl CommitmentTransaction {
        fn make_transaction(obscured_commitment_transaction_number: u64, txins: Vec<TxIn>, outputs: Vec<TxOut>) -> Transaction {
                Transaction {
                        version: 2,
-                       lock_time: ((0x20 as u32) << 8 * 3) | ((obscured_commitment_transaction_number & 0xffffffu64) as u32),
+                       lock_time: PackedLockTime(((0x20 as u32) << 8 * 3) | ((obscured_commitment_transaction_number & 0xffffffu64) as u32)),
                        input: txins,
                        output: outputs,
                }
@@ -1289,9 +1388,9 @@ impl CommitmentTransaction {
                        ins.push(TxIn {
                                previous_output: channel_parameters.funding_outpoint(),
                                script_sig: Script::new(),
-                               sequence: ((0x80 as u32) << 8 * 3)
-                                       | ((obscured_commitment_transaction_number >> 3 * 8) as u32),
-                               witness: Vec::new(),
+                               sequence: Sequence(((0x80 as u32) << 8 * 3)
+                                       | ((obscured_commitment_transaction_number >> 3 * 8) as u32)),
+                               witness: Witness::new(),
                        });
                        ins
                };
@@ -1401,7 +1500,7 @@ impl<'a> TrustedCommitmentTransaction<'a> {
        ///
        /// The returned Vec has one entry for each HTLC, and in the same order.
        ///
-       /// This function is only valid in the holder commitment context, it always uses SigHashType::All.
+       /// This function is only valid in the holder commitment context, it always uses EcdsaSighashType::All.
        pub fn get_htlc_sigs<T: secp256k1::Signing>(&self, htlc_base_key: &SecretKey, channel_parameters: &DirectedChannelTransactionParameters, secp_ctx: &Secp256k1<T>) -> Result<Vec<Signature>, ()> {
                let inner = self.inner;
                let keys = &inner.keys;
@@ -1411,11 +1510,11 @@ impl<'a> TrustedCommitmentTransaction<'a> {
 
                for this_htlc in inner.htlcs.iter() {
                        assert!(this_htlc.transaction_output_index.is_some());
-                       let htlc_tx = build_htlc_transaction(&txid, inner.feerate_per_kw, channel_parameters.contest_delay(), &this_htlc, self.opt_anchors(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+                       let htlc_tx = build_htlc_transaction(&txid, inner.feerate_per_kw, channel_parameters.contest_delay(), &this_htlc, self.opt_anchors(), self.opt_non_zero_fee_anchors.is_some(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 
                        let htlc_redeemscript = get_htlc_redeemscript_with_explicit_keys(&this_htlc, self.opt_anchors(), &keys.broadcaster_htlc_key, &keys.countersignatory_htlc_key, &keys.revocation_key);
 
-                       let sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, this_htlc.amount_msat / 1000, SigHashType::All)[..]);
+                       let sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).segwit_signature_hash(0, &htlc_redeemscript, this_htlc.amount_msat / 1000, EcdsaSighashType::All).unwrap()[..]);
                        ret.push(sign(secp_ctx, &sighash, &holder_htlc_key));
                }
                Ok(ret)
@@ -1433,19 +1532,21 @@ impl<'a> TrustedCommitmentTransaction<'a> {
                // Further, we should never be provided the preimage for an HTLC-Timeout transaction.
                if  this_htlc.offered && preimage.is_some() { unreachable!(); }
 
-               let mut htlc_tx = build_htlc_transaction(&txid, inner.feerate_per_kw, channel_parameters.contest_delay(), &this_htlc, self.opt_anchors(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+               let mut htlc_tx = build_htlc_transaction(&txid, inner.feerate_per_kw, channel_parameters.contest_delay(), &this_htlc, self.opt_anchors(), self.opt_non_zero_fee_anchors.is_some(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 
                let htlc_redeemscript = get_htlc_redeemscript_with_explicit_keys(&this_htlc, self.opt_anchors(), &keys.broadcaster_htlc_key, &keys.countersignatory_htlc_key, &keys.revocation_key);
 
-               let sighashtype = if self.opt_anchors() { SigHashType::SinglePlusAnyoneCanPay } else { SigHashType::All };
+               let sighashtype = if self.opt_anchors() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
 
                // First push the multisig dummy, note that due to BIP147 (NULLDUMMY) it must be a zero-length element.
                htlc_tx.input[0].witness.push(Vec::new());
 
-               htlc_tx.input[0].witness.push(counterparty_signature.serialize_der().to_vec());
-               htlc_tx.input[0].witness.push(signature.serialize_der().to_vec());
-               htlc_tx.input[0].witness[1].push(sighashtype as u8);
-               htlc_tx.input[0].witness[2].push(SigHashType::All as u8);
+               let mut cp_sig_ser = counterparty_signature.serialize_der().to_vec();
+               cp_sig_ser.push(sighashtype as u8);
+               htlc_tx.input[0].witness.push(cp_sig_ser);
+               let mut holder_sig_ser = signature.serialize_der().to_vec();
+               holder_sig_ser.push(EcdsaSighashType::All as u8);
+               htlc_tx.input[0].witness.push(holder_sig_ser);
 
                if this_htlc.offered {
                        // Due to BIP146 (MINIMALIF) this must be a zero-length element to relay.
@@ -1498,14 +1599,15 @@ fn get_p2wpkh_redeemscript(key: &PublicKey) -> Script {
 #[cfg(test)]
 mod tests {
        use super::CounterpartyCommitmentSecrets;
-       use ::{hex, chain};
-       use prelude::*;
-       use ln::chan_utils::{get_htlc_redeemscript, get_to_countersignatory_with_anchors_redeemscript, get_p2wpkh_redeemscript, CommitmentTransaction, TxCreationKeys, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, HTLCOutputInCommitment};
+       use crate::{hex, chain};
+       use crate::prelude::*;
+       use crate::ln::chan_utils::{get_htlc_redeemscript, get_to_countersignatory_with_anchors_redeemscript, get_p2wpkh_redeemscript, CommitmentTransaction, TxCreationKeys, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, HTLCOutputInCommitment};
        use bitcoin::secp256k1::{PublicKey, SecretKey, Secp256k1};
-       use util::test_utils;
-       use chain::keysinterface::{KeysInterface, BaseSign};
-       use bitcoin::Network;
-       use ln::PaymentHash;
+       use crate::util::test_utils;
+       use crate::chain::keysinterface::{KeysInterface, BaseSign};
+       use bitcoin::{Network, Txid};
+       use bitcoin::hashes::Hash;
+       use crate::ln::PaymentHash;
        use bitcoin::hashes::hex::ToHex;
 
        #[test]
@@ -1529,8 +1631,9 @@ mod tests {
                        holder_selected_contest_delay: 0,
                        is_outbound_from_holder: false,
                        counterparty_parameters: Some(CounterpartyChannelTransactionParameters { pubkeys: counterparty_pubkeys.clone(), selected_contest_delay: 0 }),
-                       funding_outpoint: Some(chain::transaction::OutPoint { txid: Default::default(), index: 0 }),
-                       opt_anchors: None
+                       funding_outpoint: Some(chain::transaction::OutPoint { txid: Txid::all_zeros(), index: 0 }),
+                       opt_anchors: None,
+                       opt_non_zero_fee_anchors: None,
                };
 
                let mut htlcs_with_aux: Vec<(_, ())> = Vec::new();