1 // This file is Copyright its original authors, visible in version control
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
10 use crate::ln::channel::{ANCHOR_OUTPUT_VALUE_SATOSHI, MIN_CHAN_DUST_LIMIT_SATOSHIS};
11 use crate::ln::chan_utils::{HTLCOutputInCommitment, ChannelPublicKeys, HolderCommitmentTransaction, CommitmentTransaction, ChannelTransactionParameters, TrustedCommitmentTransaction, ClosingTransaction};
12 use crate::ln::channel_keys::{HtlcKey};
13 use crate::ln::{msgs, PaymentPreimage};
14 use crate::sign::{InMemorySigner, ChannelSigner};
15 use crate::sign::ecdsa::{EcdsaChannelSigner, WriteableEcdsaChannelSigner};
17 #[allow(unused_imports)]
18 use crate::prelude::*;
21 use crate::sync::{Mutex, Arc};
22 #[cfg(test)] use crate::sync::MutexGuard;
24 use bitcoin::blockdata::transaction::Transaction;
25 use bitcoin::hashes::Hash;
27 use bitcoin::sighash::EcdsaSighashType;
29 use bitcoin::secp256k1;
31 use bitcoin::secp256k1::All;
32 use bitcoin::secp256k1::{SecretKey, PublicKey};
33 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
35 use musig2::types::{PartialSignature, PublicNonce, SecretNonce};
36 use crate::sign::HTLCDescriptor;
37 use crate::util::ser::{Writeable, Writer};
39 use crate::ln::features::ChannelTypeFeatures;
41 use crate::ln::msgs::PartialSignatureWithNonce;
43 use crate::sign::taproot::TaprootChannelSigner;
45 /// Initial value for revoked commitment downward counter
46 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
48 /// An implementation of Sign that enforces some policy checks. The current checks
49 /// are an incomplete set. They include:
51 /// - When signing, the holder transaction has not been revoked
52 /// - When revoking, the holder transaction has not been signed
53 /// - The holder commitment number is monotonic and without gaps
54 /// - The revoked holder commitment number is monotonic and without gaps
55 /// - There is at least one unrevoked holder transaction at all times
56 /// - The counterparty commitment number is monotonic and without gaps
57 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
59 /// Eventually we will probably want to expose a variant of this which would essentially
60 /// be what you'd want to run on a hardware wallet.
62 /// Note that counterparty signatures on the holder transaction are not checked, but it should
63 /// be in a complete implementation.
65 /// Note that before we do so we should ensure its serialization format has backwards- and
66 /// forwards-compatibility prefix/suffixes!
68 pub struct TestChannelSigner {
69 pub inner: InMemorySigner,
70 /// Channel state used for policy enforcement
71 pub state: Arc<Mutex<EnforcementState>>,
72 pub disable_revocation_policy_check: bool,
73 /// When `true` (the default), the signer will respond immediately with signatures. When `false`,
74 /// the signer will return an error indicating that it is unavailable.
75 pub available: Arc<Mutex<bool>>,
78 impl PartialEq for TestChannelSigner {
79 fn eq(&self, o: &Self) -> bool {
80 Arc::ptr_eq(&self.state, &o.state)
84 impl TestChannelSigner {
85 /// Construct an TestChannelSigner
86 pub fn new(inner: InMemorySigner) -> Self {
87 let state = Arc::new(Mutex::new(EnforcementState::new()));
91 disable_revocation_policy_check: false,
92 available: Arc::new(Mutex::new(true)),
96 /// Construct an TestChannelSigner with externally managed storage
98 /// Since there are multiple copies of this struct for each channel, some coordination is needed
99 /// so that all copies are aware of enforcement state. A pointer to this state is provided
100 /// here, usually by an implementation of KeysInterface.
101 pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
105 disable_revocation_policy_check,
106 available: Arc::new(Mutex::new(true)),
110 pub fn channel_type_features(&self) -> &ChannelTypeFeatures { self.inner.channel_type_features().unwrap() }
113 pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
114 self.state.lock().unwrap()
117 /// Marks the signer's availability.
119 /// When `true`, methods are forwarded to the underlying signer as normal. When `false`, some
120 /// methods will return `Err` indicating that the signer is unavailable. Intended to be used for
121 /// testing asynchronous signing.
122 pub fn set_available(&self, available: bool) {
123 *self.available.lock().unwrap() = available;
127 impl ChannelSigner for TestChannelSigner {
128 fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
129 self.inner.get_per_commitment_point(idx, secp_ctx)
132 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
134 let mut state = self.state.lock().unwrap();
135 assert!(idx == state.last_holder_revoked_commitment || idx == state.last_holder_revoked_commitment - 1, "can only revoke the current or next unrevoked commitment - trying {}, last revoked {}", idx, state.last_holder_revoked_commitment);
136 assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
137 state.last_holder_revoked_commitment = idx;
139 self.inner.release_commitment_secret(idx)
142 fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _outbound_htlc_preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
143 let mut state = self.state.lock().unwrap();
144 let idx = holder_tx.commitment_number();
145 assert!(idx == state.last_holder_commitment || idx == state.last_holder_commitment - 1, "expecting to validate the current or next holder commitment - trying {}, current {}", idx, state.last_holder_commitment);
146 state.last_holder_commitment = idx;
150 fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
151 if !*self.available.lock().unwrap() {
154 let mut state = self.state.lock().unwrap();
155 assert!(idx == state.last_counterparty_revoked_commitment || idx == state.last_counterparty_revoked_commitment - 1, "expecting to validate the current or next counterparty revocation - trying {}, current {}", idx, state.last_counterparty_revoked_commitment);
156 state.last_counterparty_revoked_commitment = idx;
160 fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
162 fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
164 fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
165 self.inner.provide_channel_parameters(channel_parameters)
169 impl EcdsaChannelSigner for TestChannelSigner {
170 fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, inbound_htlc_preimages: Vec<PaymentPreimage>, outbound_htlc_preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
171 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
174 if !*self.available.lock().unwrap() {
177 let mut state = self.state.lock().unwrap();
178 let actual_commitment_number = commitment_tx.commitment_number();
179 let last_commitment_number = state.last_counterparty_commitment;
180 // These commitment numbers are backwards counting. We expect either the same as the previously encountered,
182 assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
183 // Ensure that the counterparty doesn't get more than two broadcastable commitments -
184 // the last and the one we are trying to sign
185 assert!(actual_commitment_number >= state.last_counterparty_revoked_commitment - 2, "cannot sign a commitment if second to last wasn't revoked - signing {} revoked {}", actual_commitment_number, state.last_counterparty_revoked_commitment);
186 state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
189 Ok(self.inner.sign_counterparty_commitment(commitment_tx, inbound_htlc_preimages, outbound_htlc_preimages, secp_ctx).unwrap())
192 fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
193 if !*self.available.lock().unwrap() {
196 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
197 let state = self.state.lock().unwrap();
198 let commitment_number = trusted_tx.commitment_number();
199 if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
200 if !self.disable_revocation_policy_check {
201 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
202 state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
205 Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
208 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
209 fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
210 Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
213 fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
214 if !*self.available.lock().unwrap() {
217 Ok(EcdsaChannelSigner::sign_justice_revoked_output(&self.inner, justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
220 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, ()> {
221 if !*self.available.lock().unwrap() {
224 Ok(EcdsaChannelSigner::sign_justice_revoked_htlc(&self.inner, justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
227 fn sign_holder_htlc_transaction(
228 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
229 secp_ctx: &Secp256k1<secp256k1::All>
230 ) -> Result<Signature, ()> {
231 if !*self.available.lock().unwrap() {
234 let state = self.state.lock().unwrap();
235 if state.last_holder_revoked_commitment - 1 != htlc_descriptor.per_commitment_number &&
236 state.last_holder_revoked_commitment - 2 != htlc_descriptor.per_commitment_number
238 if !self.disable_revocation_policy_check {
239 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
240 state.last_holder_revoked_commitment, htlc_descriptor.per_commitment_number, self.inner.commitment_seed[0])
243 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
244 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(secp_ctx));
246 let witness_script = htlc_descriptor.witness_script(secp_ctx);
247 let sighash_type = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
248 EcdsaSighashType::SinglePlusAnyoneCanPay
250 EcdsaSighashType::All
252 let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
253 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, sighash_type
255 let countersignatory_htlc_key = HtlcKey::from_basepoint(
256 &secp_ctx, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint, &htlc_descriptor.per_commitment_point,
259 secp_ctx.verify_ecdsa(
260 &hash_to_message!(sighash.as_byte_array()), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key.to_public_key()
263 Ok(EcdsaChannelSigner::sign_holder_htlc_transaction(&self.inner, htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
266 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, ()> {
267 if !*self.available.lock().unwrap() {
270 Ok(EcdsaChannelSigner::sign_counterparty_htlc_transaction(&self.inner, htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
273 fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
274 closing_tx.verify(self.inner.funding_outpoint().unwrap().into_bitcoin_outpoint())
275 .expect("derived different closing transaction");
276 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
279 fn sign_holder_anchor_input(
280 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
281 ) -> Result<Signature, ()> {
282 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
283 // As long as our minimum dust limit is enforced and is greater than our anchor output
284 // value, an anchor output can only have an index within [0, 1].
285 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
286 if !*self.available.lock().unwrap() {
289 EcdsaChannelSigner::sign_holder_anchor_input(&self.inner, anchor_tx, input, secp_ctx)
292 fn sign_channel_announcement_with_funding_key(
293 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
294 ) -> Result<Signature, ()> {
295 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
299 impl WriteableEcdsaChannelSigner for TestChannelSigner {}
302 impl TaprootChannelSigner for TestChannelSigner {
303 fn generate_local_nonce_pair(&self, commitment_number: u64, secp_ctx: &Secp256k1<All>) -> PublicNonce {
307 fn partially_sign_counterparty_commitment(&self, counterparty_nonce: PublicNonce, commitment_tx: &CommitmentTransaction, inbound_htlc_preimages: Vec<PaymentPreimage>, outbound_htlc_preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<All>) -> Result<(PartialSignatureWithNonce, Vec<secp256k1::schnorr::Signature>), ()> {
311 fn finalize_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, counterparty_partial_signature: PartialSignatureWithNonce, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
315 fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
319 fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
323 fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
327 fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
331 fn partially_sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
335 fn sign_holder_anchor_input(&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
340 impl Writeable for TestChannelSigner {
341 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
342 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
343 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
344 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
345 // and will be serialized as needed by the implementation of that trait.
346 self.inner.write(writer)?;
351 impl TestChannelSigner {
352 fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
353 commitment_tx.verify(
354 &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
355 self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
356 ).expect("derived different per-tx keys or built transaction")
359 fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
360 commitment_tx.verify(
361 &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
362 self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
363 ).expect("derived different per-tx keys or built transaction")
367 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
369 /// This structure is maintained by KeysInterface since we may have multiple copies of
370 /// the signer and they must coordinate their state.
372 pub struct EnforcementState {
373 /// The last counterparty commitment number we signed, backwards counting
374 pub last_counterparty_commitment: u64,
375 /// The last counterparty commitment they revoked, backwards counting
376 pub last_counterparty_revoked_commitment: u64,
377 /// The last holder commitment number we revoked, backwards counting
378 pub last_holder_revoked_commitment: u64,
379 /// The last validated holder commitment number, backwards counting
380 pub last_holder_commitment: u64,
383 impl EnforcementState {
384 /// Enforcement state for a new channel
385 pub fn new() -> Self {
387 last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
388 last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
389 last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
390 last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,