Add BOLT 12 features to PaymentParams
[rust-lightning] / lightning / src / ln / chan_utils.rs
index 13b632e7b4685f04ae2aef9800a68347dea286d0..9699cc78a1a3253a7635277d22c133a3517b2804 100644 (file)
@@ -8,46 +8,54 @@
 // licenses.
 
 //! Various utilities for building scripts and deriving keys related to channels. These are
-//! largely of interest for those implementing chain::keysinterface::Sign message signing by hand.
+//! largely of interest for those implementing the traits on [`chain::keysinterface`] by hand.
 
 use bitcoin::blockdata::script::{Script,Builder};
 use bitcoin::blockdata::opcodes;
 use bitcoin::blockdata::transaction::{TxIn,TxOut,OutPoint,Transaction, EcdsaSighashType};
 use bitcoin::util::sighash;
+use bitcoin::util::address::Payload;
 
 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::chain::keysinterface::EntropySource;
+use crate::ln::{PaymentHash, PaymentPreimage};
+use crate::ln::msgs::DecodeError;
+use crate::util::ser::{Readable, Writeable, Writer};
+use crate::util::transaction_utils;
 
-use bitcoin::hash_types::WPubkeyHash;
 use bitcoin::secp256k1::{SecretKey, PublicKey, Scalar};
 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature, Message};
-use bitcoin::secp256k1::Error as SecpError;
 use bitcoin::{PackedLockTime, secp256k1, Sequence, Witness};
+use bitcoin::PublicKey as BitcoinPublicKey;
 
-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;
-
-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.
+use crate::chain;
+use crate::util::crypto::{sign, sign_with_aux_rand};
+
+/// Maximum number of one-way in-flight HTLC (protocol-level value).
+pub const MAX_HTLCS: u16 = 483;
+/// The weight of a BIP141 witnessScript for a BOLT3's "offered HTLC output" on a commitment transaction, non-anchor variant.
+pub const OFFERED_HTLC_SCRIPT_WEIGHT: usize = 133;
+/// The weight of a BIP141 witnessScript for a BOLT3's "offered HTLC output" on a commitment transaction, anchor variant.
+pub const OFFERED_HTLC_SCRIPT_WEIGHT_ANCHORS: usize = 136;
+
+/// The weight of a BIP141 witnessScript for a BOLT3's "received HTLC output" 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;
+/// The weight of a BIP141 witnessScript for a BOLT3's "received HTLC output" can vary in function of its CLTV argument value.
+/// We define a range that encompasses both its non-anchors and anchors variants.
+/// This is the maximum post-anchor value.
+pub const MAX_ACCEPTED_HTLC_SCRIPT_WEIGHT: usize = 143;
 
 /// Gets the weight for an HTLC-Success transaction.
 #[inline]
@@ -65,18 +73,24 @@ pub fn htlc_timeout_tx_weight(opt_anchors: bool) -> u64 {
        if opt_anchors { HTLC_TIMEOUT_ANCHOR_TX_WEIGHT } else { HTLC_TIMEOUT_TX_WEIGHT }
 }
 
+/// Describes the type of HTLC claim as determined by analyzing the witness.
 #[derive(PartialEq, Eq)]
-pub(crate) enum HTLCClaim {
+pub enum HTLCClaim {
+       /// Claims an offered output on a commitment transaction through the timeout path.
        OfferedTimeout,
+       /// Claims an offered output on a commitment transaction through the success path.
        OfferedPreimage,
+       /// Claims an accepted output on a commitment transaction through the timeout path.
        AcceptedTimeout,
+       /// Claims an accepted output on a commitment transaction through the success path.
        AcceptedPreimage,
+       /// Claims an offered/accepted output on a commitment transaction through the revocation path.
        Revocation,
 }
 
 impl HTLCClaim {
        /// Check if a given input witness attempts to claim a HTLC.
-       pub(crate) fn from_witness(witness: &Witness) -> Option<Self> {
+       pub 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;
@@ -296,7 +310,7 @@ impl Writeable for CounterpartyCommitmentSecrets {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
                for &(ref secret, ref idx) in self.old_secrets.iter() {
                        writer.write_all(secret)?;
-                       writer.write_all(&byte_utils::be64_to_array(*idx))?;
+                       writer.write_all(&idx.to_be_bytes())?;
                }
                write_tlv_fields!(writer, {});
                Ok(())
@@ -316,32 +330,29 @@ impl Readable for CounterpartyCommitmentSecrets {
 
 /// Derives a per-commitment-transaction private key (eg an htlc key or delayed_payment key)
 /// from the base secret and the per_commitment_point.
-///
-/// Note that this is infallible iff we trust that at least one of the two input keys are randomly
-/// generated (ie our own).
-pub fn derive_private_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, base_secret: &SecretKey) -> Result<SecretKey, SecpError> {
+pub fn derive_private_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, base_secret: &SecretKey) -> SecretKey {
        let mut sha = Sha256::engine();
        sha.input(&per_commitment_point.serialize());
        sha.input(&PublicKey::from_secret_key(&secp_ctx, &base_secret).serialize());
        let res = Sha256::from_engine(sha).into_inner();
 
        base_secret.clone().add_tweak(&Scalar::from_be_bytes(res).unwrap())
+               .expect("Addition only fails if the tweak is the inverse of the key. This is not possible when the tweak contains the hash of the key.")
 }
 
 /// Derives a per-commitment-transaction public key (eg an htlc key or a delayed_payment key)
 /// from the base point and the per_commitment_key. This is the public equivalent of
 /// derive_private_key - using only public keys to derive a public key instead of private keys.
-///
-/// Note that this is infallible iff we trust that at least one of the two input keys are randomly
-/// generated (ie our own).
-pub fn derive_public_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, base_point: &PublicKey) -> Result<PublicKey, SecpError> {
+pub fn derive_public_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, base_point: &PublicKey) -> PublicKey {
        let mut sha = Sha256::engine();
        sha.input(&per_commitment_point.serialize());
        sha.input(&base_point.serialize());
        let res = Sha256::from_engine(sha).into_inner();
 
-       let hashkey = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&res)?);
+       let hashkey = PublicKey::from_secret_key(&secp_ctx,
+               &SecretKey::from_slice(&res).expect("Hashes should always be valid keys unless SHA-256 is broken"));
        base_point.combine(&hashkey)
+               .expect("Addition only fails if the tweak is the inverse of the key. This is not possible when the tweak contains the hash of the key.")
 }
 
 /// Derives a per-commitment-transaction revocation key from its constituent parts.
@@ -350,10 +361,9 @@ pub fn derive_public_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_com
 /// 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.
-///
-/// Note that this is infallible iff we trust that at least one of the two input keys are randomly
-/// generated (ie our own).
-pub fn derive_private_revocation_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_secret: &SecretKey, countersignatory_revocation_base_secret: &SecretKey) -> Result<SecretKey, SecpError> {
+pub fn derive_private_revocation_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>,
+       per_commitment_secret: &SecretKey, countersignatory_revocation_base_secret: &SecretKey)
+-> SecretKey {
        let countersignatory_revocation_base_point = PublicKey::from_secret_key(&secp_ctx, &countersignatory_revocation_base_secret);
        let per_commitment_point = PublicKey::from_secret_key(&secp_ctx, &per_commitment_secret);
 
@@ -372,9 +382,12 @@ pub fn derive_private_revocation_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1
                Sha256::from_engine(sha).into_inner()
        };
 
-       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())?;
+       let countersignatory_contrib = countersignatory_revocation_base_secret.clone().mul_tweak(&Scalar::from_be_bytes(rev_append_commit_hash_key).unwrap())
+               .expect("Multiplying a secret key by a hash is expected to never fail per secp256k1 docs");
+       let broadcaster_contrib = per_commitment_secret.clone().mul_tweak(&Scalar::from_be_bytes(commit_append_rev_hash_key).unwrap())
+               .expect("Multiplying a secret key by a hash is expected to never fail per secp256k1 docs");
        countersignatory_contrib.add_tweak(&Scalar::from_be_bytes(broadcaster_contrib.secret_bytes()).unwrap())
+               .expect("Addition only fails if the tweak is the inverse of the key. This is not possible when the tweak commits to the key.")
 }
 
 /// Derives a per-commitment-transaction revocation public key from its constituent parts. This is
@@ -388,7 +401,9 @@ pub fn derive_private_revocation_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1
 ///
 /// Note that this is infallible iff we trust that at least one of the two input keys are randomly
 /// generated (ie our own).
-pub fn derive_public_revocation_key<T: secp256k1::Verification>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, countersignatory_revocation_base_point: &PublicKey) -> Result<PublicKey, SecpError> {
+pub fn derive_public_revocation_key<T: secp256k1::Verification>(secp_ctx: &Secp256k1<T>,
+       per_commitment_point: &PublicKey, countersignatory_revocation_base_point: &PublicKey)
+-> PublicKey {
        let rev_append_commit_hash_key = {
                let mut sha = Sha256::engine();
                sha.input(&countersignatory_revocation_base_point.serialize());
@@ -404,9 +419,12 @@ pub fn derive_public_revocation_key<T: secp256k1::Verification>(secp_ctx: &Secp2
                Sha256::from_engine(sha).into_inner()
        };
 
-       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())?;
+       let countersignatory_contrib = countersignatory_revocation_base_point.clone().mul_tweak(&secp_ctx, &Scalar::from_be_bytes(rev_append_commit_hash_key).unwrap())
+               .expect("Multiplying a valid public key by a hash is expected to never fail per secp256k1 docs");
+       let broadcaster_contrib = per_commitment_point.clone().mul_tweak(&secp_ctx, &Scalar::from_be_bytes(commit_append_rev_hash_key).unwrap())
+               .expect("Multiplying a valid public key by a hash is expected to never fail per secp256k1 docs");
        countersignatory_contrib.combine(&broadcaster_contrib)
+               .expect("Addition only fails if the tweak is the inverse of the key. This is not possible when the tweak commits to the key.")
 }
 
 /// The set of public keys which are used in the creation of one commitment transaction.
@@ -445,7 +463,7 @@ impl_writeable_tlv_based!(TxCreationKeys, {
 });
 
 /// One counterparty's public keys which do not change over the life of a channel.
-#[derive(Clone, PartialEq, Eq)]
+#[derive(Clone, Debug, 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.
@@ -479,19 +497,19 @@ impl_writeable_tlv_based!(ChannelPublicKeys, {
 impl TxCreationKeys {
        /// Create per-state keys from channel base points and the per-commitment point.
        /// Key set is asymmetric and can't be used as part of counter-signatory set of transactions.
-       pub fn derive_new<T: secp256k1::Signing + secp256k1::Verification>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, broadcaster_delayed_payment_base: &PublicKey, broadcaster_htlc_base: &PublicKey, countersignatory_revocation_base: &PublicKey, countersignatory_htlc_base: &PublicKey) -> Result<TxCreationKeys, SecpError> {
-               Ok(TxCreationKeys {
+       pub fn derive_new<T: secp256k1::Signing + secp256k1::Verification>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, broadcaster_delayed_payment_base: &PublicKey, broadcaster_htlc_base: &PublicKey, countersignatory_revocation_base: &PublicKey, countersignatory_htlc_base: &PublicKey) -> TxCreationKeys {
+               TxCreationKeys {
                        per_commitment_point: per_commitment_point.clone(),
-                       revocation_key: derive_public_revocation_key(&secp_ctx, &per_commitment_point, &countersignatory_revocation_base)?,
-                       broadcaster_htlc_key: derive_public_key(&secp_ctx, &per_commitment_point, &broadcaster_htlc_base)?,
-                       countersignatory_htlc_key: derive_public_key(&secp_ctx, &per_commitment_point, &countersignatory_htlc_base)?,
-                       broadcaster_delayed_payment_key: derive_public_key(&secp_ctx, &per_commitment_point, &broadcaster_delayed_payment_base)?,
-               })
+                       revocation_key: derive_public_revocation_key(&secp_ctx, &per_commitment_point, &countersignatory_revocation_base),
+                       broadcaster_htlc_key: derive_public_key(&secp_ctx, &per_commitment_point, &broadcaster_htlc_base),
+                       countersignatory_htlc_key: derive_public_key(&secp_ctx, &per_commitment_point, &countersignatory_htlc_base),
+                       broadcaster_delayed_payment_key: derive_public_key(&secp_ctx, &per_commitment_point, &broadcaster_delayed_payment_base),
+               }
        }
 
        /// Generate per-state keys from channel static keys.
        /// Key set is asymmetric and can't be used as part of counter-signatory set of transactions.
-       pub fn from_channel_static_keys<T: secp256k1::Signing + secp256k1::Verification>(per_commitment_point: &PublicKey, broadcaster_keys: &ChannelPublicKeys, countersignatory_keys: &ChannelPublicKeys, secp_ctx: &Secp256k1<T>) -> Result<TxCreationKeys, SecpError> {
+       pub fn from_channel_static_keys<T: secp256k1::Signing + secp256k1::Verification>(per_commitment_point: &PublicKey, broadcaster_keys: &ChannelPublicKeys, countersignatory_keys: &ChannelPublicKeys, secp_ctx: &Secp256k1<T>) -> TxCreationKeys {
                TxCreationKeys::derive_new(
                        &secp_ctx,
                        &per_commitment_point,
@@ -643,13 +661,17 @@ pub fn make_funding_redeemscript(broadcaster: &PublicKey, countersignatory: &Pub
        let broadcaster_funding_key = broadcaster.serialize();
        let countersignatory_funding_key = countersignatory.serialize();
 
+       make_funding_redeemscript_from_slices(&broadcaster_funding_key, &countersignatory_funding_key)
+}
+
+pub(crate) fn make_funding_redeemscript_from_slices(broadcaster_funding_key: &[u8], countersignatory_funding_key: &[u8]) -> Script {
        let builder = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2);
        if broadcaster_funding_key[..] < countersignatory_funding_key[..] {
-               builder.push_slice(&broadcaster_funding_key)
-                       .push_slice(&countersignatory_funding_key)
+               builder.push_slice(broadcaster_funding_key)
+                       .push_slice(countersignatory_funding_key)
        } else {
-               builder.push_slice(&countersignatory_funding_key)
-                       .push_slice(&broadcaster_funding_key)
+               builder.push_slice(countersignatory_funding_key)
+                       .push_slice(broadcaster_funding_key)
        }.push_opcode(opcodes::all::OP_PUSHNUM_2).push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script()
 }
 
@@ -660,9 +682,26 @@ 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 {
+       txins.push(build_htlc_input(commitment_txid, htlc, opt_anchors));
+
+       let mut txouts: Vec<TxOut> = Vec::new();
+       txouts.push(build_htlc_output(
+               feerate_per_kw, contest_delay, htlc, opt_anchors, use_non_zero_fee_anchors,
+               broadcaster_delayed_payment_key, revocation_key
+       ));
+
+       Transaction {
+               version: 2,
+               lock_time: PackedLockTime(if htlc.offered { htlc.cltv_expiry } else { 0 }),
+               input: txins,
+               output: txouts,
+       }
+}
+
+pub(crate) fn build_htlc_input(commitment_txid: &Txid, htlc: &HTLCOutputInCommitment, opt_anchors: bool) -> TxIn {
+       TxIn {
                previous_output: OutPoint {
                        txid: commitment_txid.clone(),
                        vout: htlc.transaction_output_index.expect("Can't build an HTLC transaction for a dust output"),
@@ -670,37 +709,60 @@ pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, conte
                script_sig: Script::new(),
                sequence: Sequence(if opt_anchors { 1 } else { 0 }),
                witness: Witness::new(),
-       });
+       }
+}
 
+pub(crate) fn build_htlc_output(
+       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
+) -> TxOut {
        let weight = if htlc.offered {
                htlc_timeout_tx_weight(opt_anchors)
        } else {
                htlc_success_tx_weight(opt_anchors)
        };
-       let output_value = if opt_anchors {
+       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 {
+       TxOut {
                script_pubkey: get_revokeable_redeemscript(revocation_key, contest_delay, broadcaster_delayed_payment_key).to_v0_p2wsh(),
                value: output_value,
-       });
+       }
+}
 
-       Transaction {
-               version: 2,
-               lock_time: PackedLockTime(if htlc.offered { htlc.cltv_expiry } else { 0 }),
-               input: txins,
-               output: txouts,
+/// Returns the witness required to satisfy and spend a HTLC input.
+pub fn build_htlc_input_witness(
+       local_sig: &Signature, remote_sig: &Signature, preimage: &Option<PaymentPreimage>,
+       redeem_script: &Script, opt_anchors: bool,
+) -> Witness {
+       let remote_sighash_type = if opt_anchors {
+               EcdsaSighashType::SinglePlusAnyoneCanPay
+       } else {
+               EcdsaSighashType::All
+       };
+
+       let mut witness = Witness::new();
+       // First push the multisig dummy, note that due to BIP147 (NULLDUMMY) it must be a zero-length element.
+       witness.push(vec![]);
+       witness.push_bitcoin_signature(&remote_sig.serialize_der(), remote_sighash_type);
+       witness.push_bitcoin_signature(&local_sig.serialize_der(), EcdsaSighashType::All);
+       if let Some(preimage) = preimage {
+               witness.push(preimage.0.to_vec());
+       } else {
+               // Due to BIP146 (MINIMALIF) this must be a zero-length element to relay.
+               witness.push(vec![]);
        }
+       witness.push(redeem_script.to_bytes());
+       witness
 }
 
 /// Gets the witnessScript for the to_remote output when anchors are enabled.
 #[inline]
-pub(crate) fn get_to_countersignatory_with_anchors_redeemscript(payment_point: &PublicKey) -> Script {
+pub fn get_to_countersignatory_with_anchors_redeemscript(payment_point: &PublicKey) -> Script {
        Builder::new()
                .push_slice(&payment_point.serialize()[..])
                .push_opcode(opcodes::all::OP_CHECKSIGVERIFY)
@@ -736,12 +798,21 @@ pub(crate) fn get_anchor_output<'a>(commitment_tx: &'a Transaction, funding_pubk
                .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 ret = Witness::new();
+       ret.push_bitcoin_signature(&funding_sig.serialize_der(), EcdsaSighashType::All);
+       ret.push(anchor_redeem_script.as_bytes());
+       ret
+}
+
 /// Per-channel data used to build transactions in conjunction with the per-commitment data (CommitmentTransaction).
 /// The fields are organized by holder/counterparty.
 ///
 /// Normally, this is converted to the broadcaster/countersignatory-organized DirectedChannelTransactionParameters
 /// before use, via the as_holder_broadcastable and as_counterparty_broadcastable functions.
-#[derive(Clone)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct ChannelTransactionParameters {
        /// Holder public keys
        pub holder_pubkeys: ChannelPublicKeys,
@@ -757,11 +828,15 @@ pub struct ChannelTransactionParameters {
        pub funding_outpoint: Option<chain::transaction::OutPoint>,
        /// Are anchors (zero fee HTLC transaction variant) used for this channel. Boolean is
        /// serialization backwards-compatible.
-       pub opt_anchors: Option<()>
+       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.
-#[derive(Clone)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct CounterpartyChannelTransactionParameters {
        /// Counter-party public keys
        pub pubkeys: ChannelPublicKeys,
@@ -812,6 +887,7 @@ 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
@@ -909,7 +985,7 @@ impl_writeable_tlv_based!(HolderCommitmentTransaction, {
 
 impl HolderCommitmentTransaction {
        #[cfg(test)]
-       pub fn dummy() -> Self {
+       pub fn dummy(htlcs: &mut Vec<(HTLCOutputInCommitment, ())>) -> Self {
                let secp_ctx = Secp256k1::new();
                let dummy_key = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                let dummy_sig = sign(&secp_ctx, &secp256k1::Message::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[42; 32]).unwrap());
@@ -934,14 +1010,19 @@ impl HolderCommitmentTransaction {
                        is_outbound_from_holder: false,
                        counterparty_parameters: Some(CounterpartyChannelTransactionParameters { pubkeys: channel_pubkeys.clone(), selected_contest_delay: 0 }),
                        funding_outpoint: Some(chain::transaction::OutPoint { txid: Txid::all_zeros(), index: 0 }),
-                       opt_anchors: None
+                       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());
+               let mut counterparty_htlc_sigs = Vec::new();
+               for _ in 0..htlcs.len() {
+                       counterparty_htlc_sigs.push(dummy_sig);
+               }
+               let inner = CommitmentTransaction::new_with_auxiliary_htlc_data(0, 0, 0, false, dummy_key.clone(), dummy_key.clone(), keys, 0, htlcs, &channel_parameters.as_counterparty_broadcastable());
+               htlcs.sort_by_key(|htlc| htlc.0.transaction_output_index);
                HolderCommitmentTransaction {
                        inner,
                        counterparty_sig: dummy_sig,
-                       counterparty_htlc_sigs: Vec::new(),
+                       counterparty_htlc_sigs,
                        holder_sig_first: false
                }
        }
@@ -961,17 +1042,13 @@ 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(ser_holder_sig);
-                       tx.input[0].witness.push(ser_cp_sig);
+                       tx.input[0].witness.push_bitcoin_signature(&holder_sig.serialize_der(), EcdsaSighashType::All);
+                       tx.input[0].witness.push_bitcoin_signature(&self.counterparty_sig.serialize_der(), EcdsaSighashType::All);
                } else {
-                       tx.input[0].witness.push(ser_cp_sig);
-                       tx.input[0].witness.push(ser_holder_sig);
+                       tx.input[0].witness.push_bitcoin_signature(&self.counterparty_sig.serialize_der(), EcdsaSighashType::All);
+                       tx.input[0].witness.push_bitcoin_signature(&holder_sig.serialize_der(), EcdsaSighashType::All);
                }
 
                tx.input[0].witness.push(funding_redeemscript.as_bytes().to_vec());
@@ -1005,12 +1082,20 @@ impl BuiltCommitmentTransaction {
                hash_to_message!(sighash)
        }
 
-       /// Sign a transaction, either because we are counter-signing the counterparty's transaction or
-       /// because we are about to broadcast a holder transaction.
-       pub fn sign<T: secp256k1::Signing>(&self, funding_key: &SecretKey, funding_redeemscript: &Script, channel_value_satoshis: u64, secp_ctx: &Secp256k1<T>) -> Signature {
+       /// Signs the counterparty's commitment transaction.
+       pub fn sign_counterparty_commitment<T: secp256k1::Signing>(&self, funding_key: &SecretKey, funding_redeemscript: &Script, channel_value_satoshis: u64, secp_ctx: &Secp256k1<T>) -> Signature {
                let sighash = self.get_sighash_all(funding_redeemscript, channel_value_satoshis);
                sign(secp_ctx, &sighash, funding_key)
        }
+
+       /// Signs the holder commitment transaction because we are about to broadcast it.
+       pub fn sign_holder_commitment<T: secp256k1::Signing, ES: Deref>(
+               &self, funding_key: &SecretKey, funding_redeemscript: &Script, channel_value_satoshis: u64,
+               entropy_source: &ES, secp_ctx: &Secp256k1<T>
+       ) -> Signature where ES::Target: EntropySource {
+               let sighash = self.get_sighash_all(funding_redeemscript, channel_value_satoshis);
+               sign_with_aux_rand(secp_ctx, &sighash, funding_key, entropy_source)
+       }
 }
 
 /// This class tracks the per-transaction information needed to build a closing transaction and will
@@ -1152,6 +1237,8 @@ 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()
@@ -1185,6 +1272,7 @@ 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 {
@@ -1197,7 +1285,7 @@ impl CommitmentTransaction {
        ///
        /// Only include HTLCs that are above the dust limit for the channel.
        ///
-       /// (C-not exported) due to the generic though we likely should expose a version without
+       /// This is not exported to bindings users due to the generic though we likely should expose a version without
        pub fn new_with_auxiliary_htlc_data<T>(commitment_number: u64, to_broadcaster_value_sat: u64, to_countersignatory_value_sat: u64, opt_anchors: bool, broadcaster_funding_key: PublicKey, countersignatory_funding_key: PublicKey, keys: TxCreationKeys, feerate_per_kw: u32, htlcs_with_aux: &mut Vec<(HTLCOutputInCommitment, T)>, channel_parameters: &DirectedChannelTransactionParameters) -> CommitmentTransaction {
                // Sort outputs and populate output indices while keeping track of the auxiliary data
                let (outputs, htlcs) = Self::internal_build_outputs(&keys, to_broadcaster_value_sat, to_countersignatory_value_sat, htlcs_with_aux, channel_parameters, opt_anchors, &broadcaster_funding_key, &countersignatory_funding_key).unwrap();
@@ -1217,9 +1305,18 @@ impl CommitmentTransaction {
                                transaction,
                                txid
                        },
+                       opt_non_zero_fee_anchors: None,
                }
        }
 
+       /// Use non-zero fee anchors
+       ///
+       /// This is not exported to bindings users 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);
 
@@ -1258,7 +1355,7 @@ impl CommitmentTransaction {
                        let script = if opt_anchors {
                            get_to_countersignatory_with_anchors_redeemscript(&countersignatory_pubkeys.payment_point).to_v0_p2wsh()
                        } else {
-                           get_p2wpkh_redeemscript(&countersignatory_pubkeys.payment_point)
+                           Payload::p2wpkh(&BitcoinPublicKey::new(countersignatory_pubkeys.payment_point)).unwrap().script_pubkey()
                        };
                        txouts.push((
                                TxOut {
@@ -1395,7 +1492,7 @@ impl CommitmentTransaction {
        /// which were included in this commitment transaction in output order.
        /// The transaction index is always populated.
        ///
-       /// (C-not exported) as we cannot currently convert Vec references to/from C, though we should
+       /// This is not exported to bindings users as we cannot currently convert Vec references to/from C, though we should
        /// expose a less effecient version which creates a Vec of references in the future.
        pub fn htlcs(&self) -> &Vec<HTLCOutputInCommitment> {
                &self.htlcs
@@ -1420,7 +1517,7 @@ impl CommitmentTransaction {
        pub fn verify<T: secp256k1::Signing + secp256k1::Verification>(&self, channel_parameters: &DirectedChannelTransactionParameters, broadcaster_keys: &ChannelPublicKeys, countersignatory_keys: &ChannelPublicKeys, secp_ctx: &Secp256k1<T>) -> Result<TrustedCommitmentTransaction, ()> {
                // This is the only field of the key cache that we trust
                let per_commitment_point = self.keys.per_commitment_point;
-               let keys = TxCreationKeys::from_channel_static_keys(&per_commitment_point, broadcaster_keys, countersignatory_keys, secp_ctx).unwrap();
+               let keys = TxCreationKeys::from_channel_static_keys(&per_commitment_point, broadcaster_keys, countersignatory_keys, secp_ctx);
                if keys != self.keys {
                        return Err(());
                }
@@ -1475,21 +1572,24 @@ 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 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>, ()> {
+       pub fn get_htlc_sigs<T: secp256k1::Signing, ES: Deref>(
+               &self, htlc_base_key: &SecretKey, channel_parameters: &DirectedChannelTransactionParameters,
+               entropy_source: &ES, secp_ctx: &Secp256k1<T>,
+       ) -> Result<Vec<Signature>, ()> where ES::Target: EntropySource {
                let inner = self.inner;
                let keys = &inner.keys;
                let txid = inner.built.txid;
                let mut ret = Vec::with_capacity(inner.htlcs.len());
-               let holder_htlc_key = derive_private_key(secp_ctx, &inner.keys.per_commitment_point, htlc_base_key).map_err(|_| ())?;
+               let holder_htlc_key = derive_private_key(secp_ctx, &inner.keys.per_commitment_point, htlc_base_key);
 
                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!(&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));
+                       ret.push(sign_with_aux_rand(secp_ctx, &sighash, &holder_htlc_key, entropy_source));
                }
                Ok(ret)
        }
@@ -1506,30 +1606,13 @@ 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() { 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());
-
-               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.
-                       htlc_tx.input[0].witness.push(Vec::new());
-               } else {
-                       htlc_tx.input[0].witness.push(preimage.unwrap().0.to_vec());
-               }
-
-               htlc_tx.input[0].witness.push(htlc_redeemscript.as_bytes().to_vec());
+               htlc_tx.input[0].witness = chan_utils::build_htlc_input_witness(
+                       signature, counterparty_signature, preimage, &htlc_redeemscript, self.opt_anchors(),
+               );
                htlc_tx
        }
 }
@@ -1564,25 +1647,21 @@ pub fn get_commitment_transaction_number_obscure_factor(
                | ((res[31] as u64) << 0 * 8)
 }
 
-fn get_p2wpkh_redeemscript(key: &PublicKey) -> Script {
-       Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
-               .push_slice(&WPubkeyHash::hash(&key.serialize())[..])
-               .into_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, CommitmentTransaction, TxCreationKeys, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, HTLCOutputInCommitment};
        use bitcoin::secp256k1::{PublicKey, SecretKey, Secp256k1};
-       use util::test_utils;
-       use chain::keysinterface::{KeysInterface, BaseSign};
+       use crate::util::test_utils;
+       use crate::chain::keysinterface::{ChannelSigner, SignerProvider};
        use bitcoin::{Network, Txid};
        use bitcoin::hashes::Hash;
-       use ln::PaymentHash;
+       use crate::ln::PaymentHash;
        use bitcoin::hashes::hex::ToHex;
+       use bitcoin::util::address::Payload;
+       use bitcoin::PublicKey as BitcoinPublicKey;
 
        #[test]
        fn test_anchors() {
@@ -1591,22 +1670,23 @@ mod tests {
                let seed = [42; 32];
                let network = Network::Testnet;
                let keys_provider = test_utils::TestKeysInterface::new(&seed, network);
-               let signer = keys_provider.get_channel_signer(false, 3000);
-               let counterparty_signer = keys_provider.get_channel_signer(false, 3000);
+               let signer = keys_provider.derive_channel_signer(3000, keys_provider.generate_channel_keys_id(false, 1_000_000, 0));
+               let counterparty_signer = keys_provider.derive_channel_signer(3000, keys_provider.generate_channel_keys_id(true, 1_000_000, 1));
                let delayed_payment_base = &signer.pubkeys().delayed_payment_basepoint;
                let per_commitment_secret = SecretKey::from_slice(&hex::decode("1f1e1d1c1b1a191817161514131211100f0e0d0c0b0a09080706050403020100").unwrap()[..]).unwrap();
                let per_commitment_point = PublicKey::from_secret_key(&secp_ctx, &per_commitment_secret);
                let htlc_basepoint = &signer.pubkeys().htlc_basepoint;
                let holder_pubkeys = signer.pubkeys();
                let counterparty_pubkeys = counterparty_signer.pubkeys();
-               let keys = TxCreationKeys::derive_new(&secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &counterparty_pubkeys.revocation_basepoint, &counterparty_pubkeys.htlc_basepoint).unwrap();
+               let keys = TxCreationKeys::derive_new(&secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &counterparty_pubkeys.revocation_basepoint, &counterparty_pubkeys.htlc_basepoint);
                let mut channel_parameters = ChannelTransactionParameters {
                        holder_pubkeys: holder_pubkeys.clone(),
                        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: Txid::all_zeros(), index: 0 }),
-                       opt_anchors: None
+                       opt_anchors: None,
+                       opt_non_zero_fee_anchors: None,
                };
 
                let mut htlcs_with_aux: Vec<(_, ())> = Vec::new();
@@ -1621,7 +1701,7 @@ mod tests {
                        &mut htlcs_with_aux, &channel_parameters.as_holder_broadcastable()
                );
                assert_eq!(tx.built.transaction.output.len(), 2);
-               assert_eq!(tx.built.transaction.output[1].script_pubkey, get_p2wpkh_redeemscript(&counterparty_pubkeys.payment_point));
+               assert_eq!(tx.built.transaction.output[1].script_pubkey, Payload::p2wpkh(&BitcoinPublicKey::new(counterparty_pubkeys.payment_point)).unwrap().script_pubkey());
 
                // Generate broadcaster and counterparty outputs as well as two anchors
                let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
@@ -1687,9 +1767,9 @@ mod tests {
                assert_eq!(tx.built.transaction.output[0].script_pubkey, get_htlc_redeemscript(&received_htlc, false, &keys).to_v0_p2wsh());
                assert_eq!(tx.built.transaction.output[1].script_pubkey, get_htlc_redeemscript(&offered_htlc, false, &keys).to_v0_p2wsh());
                assert_eq!(get_htlc_redeemscript(&received_htlc, false, &keys).to_v0_p2wsh().to_hex(),
-                                  "002085cf52e41ba7c099a39df504e7b61f6de122971ceb53b06731876eaeb85e8dc5");
+                                  "0020e43a7c068553003fe68fcae424fb7b28ec5ce48cd8b6744b3945631389bad2fb");
                assert_eq!(get_htlc_redeemscript(&offered_htlc, false, &keys).to_v0_p2wsh().to_hex(),
-                                  "002049f0736bb335c61a04d2623a24df878a7592a3c51fa7258d41b2c85318265e73");
+                                  "0020215d61bba56b19e9eadb6107f5a85d7f99c40f65992443f69229c290165bc00d");
 
                // Generate broadcaster output and received and offered HTLC outputs,  with anchors
                channel_parameters.opt_anchors = Some(());
@@ -1706,9 +1786,9 @@ mod tests {
                assert_eq!(tx.built.transaction.output[2].script_pubkey, get_htlc_redeemscript(&received_htlc, true, &keys).to_v0_p2wsh());
                assert_eq!(tx.built.transaction.output[3].script_pubkey, get_htlc_redeemscript(&offered_htlc, true, &keys).to_v0_p2wsh());
                assert_eq!(get_htlc_redeemscript(&received_htlc, true, &keys).to_v0_p2wsh().to_hex(),
-                                  "002067114123af3f95405bae4fd930fc95de03e3c86baaee8b2dd29b43dd26cf613c");
+                                  "0020b70d0649c72b38756885c7a30908d912a7898dd5d79457a7280b8e9a20f3f2bc");
                assert_eq!(get_htlc_redeemscript(&offered_htlc, true, &keys).to_v0_p2wsh().to_hex(),
-                                  "0020a06e3b0d4fcf704f2b9c41e16a70099e39989466c3142b8573a1154542f28f57");
+                                  "002087a3faeb1950a469c0e2db4a79b093a41b9526e5a6fc6ef5cb949bde3be379c7");
        }
 
        #[test]