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Added anchor support to commitment HTLC outputs
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@ksedgwic
ksedgwic committed Nov 15, 2021
1 parent 2bf39a6 commit f08000b
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Showing 7 changed files with 155 additions and 92 deletions.
11 changes: 6 additions & 5 deletions lightning/src/chain/channelmonitor.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3239,6 +3239,7 @@ mod tests {
selected_contest_delay: 67,
}),
funding_outpoint: Some(funding_outpoint),
opt_anchors: None,
};
// Prune with one old state and a holder commitment tx holding a few overlaps with the
// old state.
Expand Down Expand Up @@ -3304,15 +3305,15 @@ mod tests {
let mut sum_actual_sigs = 0;

macro_rules! sign_input {
($sighash_parts: expr, $idx: expr, $amount: expr, $weight: expr, $sum_actual_sigs: expr) => {
($sighash_parts: expr, $idx: expr, $amount: expr, $weight: expr, $sum_actual_sigs: expr, $opt_anchors: expr) => {
let htlc = HTLCOutputInCommitment {
offered: if *$weight == WEIGHT_REVOKED_OFFERED_HTLC || *$weight == WEIGHT_OFFERED_HTLC { true } else { false },
amount_msat: 0,
cltv_expiry: 2 << 16,
payment_hash: PaymentHash([1; 32]),
transaction_output_index: Some($idx as u32),
};
let redeem_script = if *$weight == WEIGHT_REVOKED_OUTPUT { chan_utils::get_revokeable_redeemscript(&pubkey, 256, &pubkey) } else { chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &pubkey, &pubkey, &pubkey) };
let redeem_script = if *$weight == WEIGHT_REVOKED_OUTPUT { chan_utils::get_revokeable_redeemscript(&pubkey, 256, &pubkey) } else { chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, $opt_anchors, &pubkey, &pubkey, &pubkey) };
let sighash = hash_to_message!(&$sighash_parts.signature_hash($idx, &redeem_script, $amount, SigHashType::All)[..]);
let sig = secp_ctx.sign(&sighash, &privkey);
$sighash_parts.access_witness($idx).push(sig.serialize_der().to_vec());
Expand Down Expand Up @@ -3360,7 +3361,7 @@ mod tests {
{
let mut sighash_parts = bip143::SigHashCache::new(&mut claim_tx);
for (idx, inp) in inputs_weight.iter().enumerate() {
sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs);
sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs, false);
inputs_total_weight += inp;
}
}
Expand All @@ -3386,7 +3387,7 @@ mod tests {
{
let mut sighash_parts = bip143::SigHashCache::new(&mut claim_tx);
for (idx, inp) in inputs_weight.iter().enumerate() {
sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs);
sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs, false);
inputs_total_weight += inp;
}
}
Expand All @@ -3410,7 +3411,7 @@ mod tests {
{
let mut sighash_parts = bip143::SigHashCache::new(&mut claim_tx);
for (idx, inp) in inputs_weight.iter().enumerate() {
sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs);
sign_input!(sighash_parts, idx, 0, inp, sum_actual_sigs, false);
inputs_total_weight += inp;
}
}
Expand Down
10 changes: 7 additions & 3 deletions lightning/src/chain/keysinterface.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -505,6 +505,10 @@ impl InMemorySigner {
self.channel_parameters.as_ref().unwrap()
}

/// Whether anchors should be used.
/// Will panic if ready_channel wasn't called.
pub fn opt_anchors(&self) -> bool { self.get_channel_parameters().opt_anchors.is_some() }

/// Sign the single input of spend_tx at index `input_idx` which spends the output
/// described by descriptor, returning the witness stack for the input.
///
Expand Down Expand Up @@ -594,7 +598,7 @@ impl BaseSign for InMemorySigner {
let mut htlc_sigs = Vec::with_capacity(commitment_tx.htlcs().len());
for htlc in commitment_tx.htlcs() {
let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_tx.feerate_per_kw(), self.holder_selected_contest_delay(), htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, self.opt_anchors(), &keys);
let htlc_sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, SigHashType::All)[..]);
let holder_htlc_key = chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key).map_err(|_| ())?;
htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &holder_htlc_key));
Expand Down Expand Up @@ -648,7 +652,7 @@ impl BaseSign for InMemorySigner {
let witness_script = {
let counterparty_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint).map_err(|_| ())?;
let holder_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint).map_err(|_| ())?;
chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, self.opt_anchors(), &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
};
let mut sighash_parts = bip143::SigHashCache::new(justice_tx);
let sighash = hash_to_message!(&sighash_parts.signature_hash(input, &witness_script, amount, SigHashType::All)[..]);
Expand All @@ -660,7 +664,7 @@ impl BaseSign for InMemorySigner {
let witness_script = if let Ok(revocation_pubkey) = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
if let Ok(counterparty_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint) {
if let Ok(htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey)
chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, self.opt_anchors(), &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey)
} else { return Err(()) }
} else { return Err(()) }
} else { return Err(()) };
Expand Down
2 changes: 2 additions & 0 deletions lightning/src/chain/onchaintx.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -785,6 +785,8 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
htlc_tx
}

pub(crate) fn opt_anchors(&self) -> bool { self.channel_transaction_parameters.opt_anchors.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();
Expand Down
6 changes: 3 additions & 3 deletions lightning/src/chain/package.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -341,7 +341,7 @@ impl PackageSolvingData {
},
PackageSolvingData::RevokedHTLCOutput(ref outp) => {
if let Ok(chan_keys) = TxCreationKeys::derive_new(&onchain_handler.secp_ctx, &outp.per_commitment_point, &outp.counterparty_delayed_payment_base_key, &outp.counterparty_htlc_base_key, &onchain_handler.signer.pubkeys().revocation_basepoint, &onchain_handler.signer.pubkeys().htlc_basepoint) {
let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);
let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, onchain_handler.opt_anchors(), &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);
//TODO: should we panic on signer failure ?
if let Ok(sig) = onchain_handler.signer.sign_justice_revoked_htlc(&bumped_tx, i, outp.amount, &outp.per_commitment_key, &outp.htlc, &onchain_handler.secp_ctx) {
bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
Expand All @@ -353,7 +353,7 @@ impl PackageSolvingData {
},
PackageSolvingData::CounterpartyOfferedHTLCOutput(ref outp) => {
if let Ok(chan_keys) = TxCreationKeys::derive_new(&onchain_handler.secp_ctx, &outp.per_commitment_point, &outp.counterparty_delayed_payment_base_key, &outp.counterparty_htlc_base_key, &onchain_handler.signer.pubkeys().revocation_basepoint, &onchain_handler.signer.pubkeys().htlc_basepoint) {
let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);
let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, onchain_handler.opt_anchors(), &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);

if let Ok(sig) = onchain_handler.signer.sign_counterparty_htlc_transaction(&bumped_tx, i, &outp.htlc.amount_msat / 1000, &outp.per_commitment_point, &outp.htlc, &onchain_handler.secp_ctx) {
bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
Expand All @@ -365,7 +365,7 @@ impl PackageSolvingData {
},
PackageSolvingData::CounterpartyReceivedHTLCOutput(ref outp) => {
if let Ok(chan_keys) = TxCreationKeys::derive_new(&onchain_handler.secp_ctx, &outp.per_commitment_point, &outp.counterparty_delayed_payment_base_key, &outp.counterparty_htlc_base_key, &onchain_handler.signer.pubkeys().revocation_basepoint, &onchain_handler.signer.pubkeys().htlc_basepoint) {
let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);
let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, onchain_handler.opt_anchors(), &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);

bumped_tx.lock_time = outp.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) = onchain_handler.signer.sign_counterparty_htlc_transaction(&bumped_tx, i, &outp.htlc.amount_msat / 1000, &outp.per_commitment_point, &outp.htlc, &onchain_handler.secp_ctx) {
Expand Down
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