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Merged
merged 3 commits into from
Dec 3, 2022
Merged

Remove cryptographically unreachable error conditions #1887

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2746190
Remove unreachable `Err` cases on `derive_{public,private}_key`
TheBlueMatt Nov 30, 2022
5671d29
Remove unreachable `Err` cases on `derive_*_revocation_key`
TheBlueMatt Nov 30, 2022
2cfc1db
Remove unreachable `Err` cases when constructing `TxCreationKeys`
TheBlueMatt Nov 30, 2022
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41 changes: 14 additions & 27 deletions lightning/src/chain/channelmonitor.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2443,8 +2443,8 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
let secret = self.get_secret(commitment_number).unwrap();
let per_commitment_key = ignore_error!(SecretKey::from_slice(&secret));
let per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key);
let revocation_pubkey = ignore_error!(chan_utils::derive_public_revocation_key(&self.secp_ctx, &per_commitment_point, &self.holder_revocation_basepoint));
let delayed_key = ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, &PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key), &self.counterparty_commitment_params.counterparty_delayed_payment_base_key));
let revocation_pubkey = chan_utils::derive_public_revocation_key(&self.secp_ctx, &per_commitment_point, &self.holder_revocation_basepoint);
let delayed_key = chan_utils::derive_public_key(&self.secp_ctx, &PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key), &self.counterparty_commitment_params.counterparty_delayed_payment_base_key);

let revokeable_redeemscript = chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.counterparty_commitment_params.on_counterparty_tx_csv, &delayed_key);
let revokeable_p2wsh = revokeable_redeemscript.to_v0_p2wsh();
Expand Down Expand Up @@ -2556,31 +2556,18 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
} else { return (claimable_outpoints, to_counterparty_output_info); };

if let Some(transaction) = tx {
let revokeable_p2wsh_opt =
if let Ok(revocation_pubkey) = chan_utils::derive_public_revocation_key(
&self.secp_ctx, &per_commitment_point, &self.holder_revocation_basepoint)
{
if let Ok(delayed_key) = chan_utils::derive_public_key(&self.secp_ctx,
&per_commitment_point,
&self.counterparty_commitment_params.counterparty_delayed_payment_base_key)
{
Some(chan_utils::get_revokeable_redeemscript(&revocation_pubkey,
self.counterparty_commitment_params.on_counterparty_tx_csv,
&delayed_key).to_v0_p2wsh())
} else {
debug_assert!(false, "Failed to derive a delayed payment key for a commitment state we accepted");
None
}
} else {
debug_assert!(false, "Failed to derive a revocation pubkey key for a commitment state we accepted");
None
};
if let Some(revokeable_p2wsh) = revokeable_p2wsh_opt {
for (idx, outp) in transaction.output.iter().enumerate() {
if outp.script_pubkey == revokeable_p2wsh {
to_counterparty_output_info =
Some((idx.try_into().expect("Can't have > 2^32 outputs"), outp.value));
}
let revocation_pubkey = chan_utils::derive_public_revocation_key(
&self.secp_ctx, &per_commitment_point, &self.holder_revocation_basepoint);
let delayed_key = chan_utils::derive_public_key(&self.secp_ctx,
&per_commitment_point,
&self.counterparty_commitment_params.counterparty_delayed_payment_base_key);
let revokeable_p2wsh = chan_utils::get_revokeable_redeemscript(&revocation_pubkey,
self.counterparty_commitment_params.on_counterparty_tx_csv,
&delayed_key).to_v0_p2wsh();
for (idx, outp) in transaction.output.iter().enumerate() {
if outp.script_pubkey == revokeable_p2wsh {
to_counterparty_output_info =
Some((idx.try_into().expect("Can't have > 2^32 outputs"), outp.value));
}
}
}
Expand Down
40 changes: 17 additions & 23 deletions lightning/src/chain/keysinterface.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -655,8 +655,7 @@ impl InMemorySigner {
if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint() { return Err(()); }
if spend_tx.input[input_idx].sequence.0 != descriptor.to_self_delay as u32 { return Err(()); }

let delayed_payment_key = chan_utils::derive_private_key(&secp_ctx, &descriptor.per_commitment_point, &self.delayed_payment_base_key)
.expect("We constructed the payment_base_key, so we can only fail here if the RNG is busted.");
let delayed_payment_key = chan_utils::derive_private_key(&secp_ctx, &descriptor.per_commitment_point, &self.delayed_payment_base_key);
let delayed_payment_pubkey = PublicKey::from_secret_key(&secp_ctx, &delayed_payment_key);
let witness_script = chan_utils::get_revokeable_redeemscript(&descriptor.revocation_pubkey, descriptor.to_self_delay, &delayed_payment_pubkey);
let sighash = hash_to_message!(&sighash::SighashCache::new(spend_tx).segwit_signature_hash(input_idx, &witness_script, descriptor.output.value, EcdsaSighashType::All).unwrap()[..]);
Expand Down Expand Up @@ -710,7 +709,7 @@ impl BaseSign for InMemorySigner {
let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, self.opt_anchors(), &keys);
let htlc_sighashtype = if self.opt_anchors() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
let htlc_sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).segwit_signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, htlc_sighashtype).unwrap()[..]);
let holder_htlc_key = chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key).map_err(|_| ())?;
let holder_htlc_key = chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key);
htlc_sigs.push(sign(secp_ctx, &htlc_sighash, &holder_htlc_key));
}

Expand Down Expand Up @@ -743,11 +742,11 @@ impl BaseSign for InMemorySigner {
}

fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
let revocation_key = chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key).map_err(|_| ())?;
let revocation_key = chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key);
let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
let revocation_pubkey = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint).map_err(|_| ())?;
let revocation_pubkey = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint);
let witness_script = {
let counterparty_delayedpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().delayed_payment_basepoint).map_err(|_| ())?;
let counterparty_delayedpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().delayed_payment_basepoint);
chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.holder_selected_contest_delay(), &counterparty_delayedpubkey)
};
let mut sighash_parts = sighash::SighashCache::new(justice_tx);
Expand All @@ -756,12 +755,12 @@ impl BaseSign for InMemorySigner {
}

fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
let revocation_key = chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key).map_err(|_| ())?;
let revocation_key = chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key);
let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
let revocation_pubkey = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint).map_err(|_| ())?;
let revocation_pubkey = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint);
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(|_| ())?;
let counterparty_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint);
let holder_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint);
chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, self.opt_anchors(), &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
};
let mut sighash_parts = sighash::SighashCache::new(justice_tx);
Expand All @@ -770,19 +769,14 @@ impl BaseSign for InMemorySigner {
}

fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
if let Ok(htlc_key) = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key) {
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, self.opt_anchors(), &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey)
} else { return Err(()) }
} else { return Err(()) }
} else { return Err(()) };
let mut sighash_parts = sighash::SighashCache::new(htlc_tx);
let sighash = hash_to_message!(&sighash_parts.segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All).unwrap()[..]);
return Ok(sign(secp_ctx, &sighash, &htlc_key))
}
Err(())
let htlc_key = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key);
let revocation_pubkey = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint);
let counterparty_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint);
let htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint);
let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, self.opt_anchors(), &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey);
let mut sighash_parts = sighash::SighashCache::new(htlc_tx);
let sighash = hash_to_message!(&sighash_parts.segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All).unwrap()[..]);
Ok(sign(secp_ctx, &sighash, &htlc_key))
}

fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
Expand Down
84 changes: 40 additions & 44 deletions lightning/src/chain/package.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -381,57 +381,53 @@ impl PackageSolvingData {
fn finalize_input<Signer: Sign>(&self, bumped_tx: &mut Transaction, i: usize, onchain_handler: &mut OnchainTxHandler<Signer>) -> bool {
match self {
PackageSolvingData::RevokedOutput(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_revokeable_redeemscript(&chan_keys.revocation_key, outp.on_counterparty_tx_csv, &chan_keys.broadcaster_delayed_payment_key);
//TODO: should we panic on signer failure ?
if let Ok(sig) = onchain_handler.signer.sign_justice_revoked_output(&bumped_tx, i, outp.amount, &outp.per_commitment_key, &onchain_handler.secp_ctx) {
let mut ser_sig = sig.serialize_der().to_vec();
ser_sig.push(EcdsaSighashType::All as u8);
bumped_tx.input[i].witness.push(ser_sig);
bumped_tx.input[i].witness.push(vec!(1));
bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
} else { return false; }
}
let 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_revokeable_redeemscript(&chan_keys.revocation_key, outp.on_counterparty_tx_csv, &chan_keys.broadcaster_delayed_payment_key);
//TODO: should we panic on signer failure ?
if let Ok(sig) = onchain_handler.signer.sign_justice_revoked_output(&bumped_tx, i, outp.amount, &outp.per_commitment_key, &onchain_handler.secp_ctx) {
let mut ser_sig = sig.serialize_der().to_vec();
ser_sig.push(EcdsaSighashType::All as u8);
bumped_tx.input[i].witness.push(ser_sig);
bumped_tx.input[i].witness.push(vec!(1));
bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
} else { return false; }
},
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, 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) {
let mut ser_sig = sig.serialize_der().to_vec();
ser_sig.push(EcdsaSighashType::All as u8);
bumped_tx.input[i].witness.push(ser_sig);
bumped_tx.input[i].witness.push(chan_keys.revocation_key.clone().serialize().to_vec());
bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
} else { return false; }
}
let 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, 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) {
let mut ser_sig = sig.serialize_der().to_vec();
ser_sig.push(EcdsaSighashType::All as u8);
bumped_tx.input[i].witness.push(ser_sig);
bumped_tx.input[i].witness.push(chan_keys.revocation_key.clone().serialize().to_vec());
bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
} else { return false; }
},
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, 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) {
let mut ser_sig = sig.serialize_der().to_vec();
ser_sig.push(EcdsaSighashType::All as u8);
bumped_tx.input[i].witness.push(ser_sig);
bumped_tx.input[i].witness.push(outp.preimage.0.to_vec());
bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
}
let 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, 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) {
let mut ser_sig = sig.serialize_der().to_vec();
ser_sig.push(EcdsaSighashType::All as u8);
bumped_tx.input[i].witness.push(ser_sig);
bumped_tx.input[i].witness.push(outp.preimage.0.to_vec());
bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
}
},
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, onchain_handler.opt_anchors(), &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);

bumped_tx.lock_time = PackedLockTime(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) {
let mut ser_sig = sig.serialize_der().to_vec();
ser_sig.push(EcdsaSighashType::All as u8);
bumped_tx.input[i].witness.push(ser_sig);
// 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 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, onchain_handler.opt_anchors(), &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);

bumped_tx.lock_time = PackedLockTime(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) {
let mut ser_sig = sig.serialize_der().to_vec();
ser_sig.push(EcdsaSighashType::All as u8);
bumped_tx.input[i].witness.push(ser_sig);
// 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());
}
},
_ => { panic!("API Error!"); }
Expand Down
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