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 use crate::prelude::*;
19 use crate::sync::{Mutex, Arc};
20 #[cfg(test)] use crate::sync::MutexGuard;
22 use bitcoin::blockdata::transaction::Transaction;
23 use bitcoin::hashes::Hash;
25 use bitcoin::sighash::EcdsaSighashType;
27 use bitcoin::secp256k1;
29 use bitcoin::secp256k1::All;
30 use bitcoin::secp256k1::{SecretKey, PublicKey};
31 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
33 use musig2::types::{PartialSignature, PublicNonce, SecretNonce};
34 use crate::sign::HTLCDescriptor;
35 use crate::util::ser::{Writeable, Writer};
37 use crate::ln::features::ChannelTypeFeatures;
39 use crate::ln::msgs::PartialSignatureWithNonce;
41 use crate::sign::taproot::TaprootChannelSigner;
43 /// Initial value for revoked commitment downward counter
44 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
46 /// An implementation of Sign that enforces some policy checks. The current checks
47 /// are an incomplete set. They include:
49 /// - When signing, the holder transaction has not been revoked
50 /// - When revoking, the holder transaction has not been signed
51 /// - The holder commitment number is monotonic and without gaps
52 /// - The revoked holder commitment number is monotonic and without gaps
53 /// - There is at least one unrevoked holder transaction at all times
54 /// - The counterparty commitment number is monotonic and without gaps
55 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
57 /// Eventually we will probably want to expose a variant of this which would essentially
58 /// be what you'd want to run on a hardware wallet.
60 /// Note that counterparty signatures on the holder transaction are not checked, but it should
61 /// be in a complete implementation.
63 /// Note that before we do so we should ensure its serialization format has backwards- and
64 /// forwards-compatibility prefix/suffixes!
66 pub struct TestChannelSigner {
67 pub inner: InMemorySigner,
68 /// Channel state used for policy enforcement
69 pub state: Arc<Mutex<EnforcementState>>,
70 pub disable_revocation_policy_check: bool,
71 /// When `true` (the default), the signer will respond immediately with signatures. When `false`,
72 /// the signer will return an error indicating that it is unavailable.
73 pub available: Arc<Mutex<bool>>,
76 impl PartialEq for TestChannelSigner {
77 fn eq(&self, o: &Self) -> bool {
78 Arc::ptr_eq(&self.state, &o.state)
82 impl TestChannelSigner {
83 /// Construct an TestChannelSigner
84 pub fn new(inner: InMemorySigner) -> Self {
85 let state = Arc::new(Mutex::new(EnforcementState::new()));
89 disable_revocation_policy_check: false,
90 available: Arc::new(Mutex::new(true)),
94 /// Construct an TestChannelSigner with externally managed storage
96 /// Since there are multiple copies of this struct for each channel, some coordination is needed
97 /// so that all copies are aware of enforcement state. A pointer to this state is provided
98 /// here, usually by an implementation of KeysInterface.
99 pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
103 disable_revocation_policy_check,
104 available: Arc::new(Mutex::new(true)),
108 pub fn channel_type_features(&self) -> &ChannelTypeFeatures { self.inner.channel_type_features().unwrap() }
111 pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
112 self.state.lock().unwrap()
115 /// Marks the signer's availability.
117 /// When `true`, methods are forwarded to the underlying signer as normal. When `false`, some
118 /// methods will return `Err` indicating that the signer is unavailable. Intended to be used for
119 /// testing asynchronous signing.
121 pub fn set_available(&self, available: bool) {
122 *self.available.lock().unwrap() = available;
126 impl ChannelSigner for TestChannelSigner {
127 fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
128 self.inner.get_per_commitment_point(idx, secp_ctx)
131 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
133 let mut state = self.state.lock().unwrap();
134 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);
135 assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
136 state.last_holder_revoked_commitment = idx;
138 self.inner.release_commitment_secret(idx)
141 fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _outbound_htlc_preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
142 let mut state = self.state.lock().unwrap();
143 let idx = holder_tx.commitment_number();
144 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);
145 state.last_holder_commitment = idx;
149 fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
150 if !*self.available.lock().unwrap() {
153 let mut state = self.state.lock().unwrap();
154 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);
155 state.last_counterparty_revoked_commitment = idx;
159 fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
161 fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
163 fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
164 self.inner.provide_channel_parameters(channel_parameters)
168 impl EcdsaChannelSigner for TestChannelSigner {
169 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>), ()> {
170 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
173 if !*self.available.lock().unwrap() {
176 let mut state = self.state.lock().unwrap();
177 let actual_commitment_number = commitment_tx.commitment_number();
178 let last_commitment_number = state.last_counterparty_commitment;
179 // These commitment numbers are backwards counting. We expect either the same as the previously encountered,
181 assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
182 // Ensure that the counterparty doesn't get more than two broadcastable commitments -
183 // the last and the one we are trying to sign
184 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);
185 state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
188 Ok(self.inner.sign_counterparty_commitment(commitment_tx, inbound_htlc_preimages, outbound_htlc_preimages, secp_ctx).unwrap())
191 fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
192 if !*self.available.lock().unwrap() {
195 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
196 let state = self.state.lock().unwrap();
197 let commitment_number = trusted_tx.commitment_number();
198 if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
199 if !self.disable_revocation_policy_check {
200 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
201 state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
204 Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
207 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
208 fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
209 Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
212 fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
213 Ok(EcdsaChannelSigner::sign_justice_revoked_output(&self.inner, justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
216 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, ()> {
217 Ok(EcdsaChannelSigner::sign_justice_revoked_htlc(&self.inner, justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
220 fn sign_holder_htlc_transaction(
221 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
222 secp_ctx: &Secp256k1<secp256k1::All>
223 ) -> Result<Signature, ()> {
224 let state = self.state.lock().unwrap();
225 if state.last_holder_revoked_commitment - 1 != htlc_descriptor.per_commitment_number &&
226 state.last_holder_revoked_commitment - 2 != htlc_descriptor.per_commitment_number
228 if !self.disable_revocation_policy_check {
229 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
230 state.last_holder_revoked_commitment, htlc_descriptor.per_commitment_number, self.inner.commitment_seed[0])
233 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
234 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(secp_ctx));
236 let witness_script = htlc_descriptor.witness_script(secp_ctx);
237 let sighash_type = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
238 EcdsaSighashType::SinglePlusAnyoneCanPay
240 EcdsaSighashType::All
242 let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
243 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, sighash_type
245 let countersignatory_htlc_key = HtlcKey::from_basepoint(
246 &secp_ctx, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint, &htlc_descriptor.per_commitment_point,
249 secp_ctx.verify_ecdsa(
250 &hash_to_message!(sighash.as_byte_array()), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key.to_public_key()
253 Ok(EcdsaChannelSigner::sign_holder_htlc_transaction(&self.inner, htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
256 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, ()> {
257 Ok(EcdsaChannelSigner::sign_counterparty_htlc_transaction(&self.inner, htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
260 fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
261 closing_tx.verify(self.inner.funding_outpoint().unwrap().into_bitcoin_outpoint())
262 .expect("derived different closing transaction");
263 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
266 fn sign_holder_anchor_input(
267 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
268 ) -> Result<Signature, ()> {
269 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
270 // As long as our minimum dust limit is enforced and is greater than our anchor output
271 // value, an anchor output can only have an index within [0, 1].
272 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
273 EcdsaChannelSigner::sign_holder_anchor_input(&self.inner, anchor_tx, input, secp_ctx)
276 fn sign_channel_announcement_with_funding_key(
277 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
278 ) -> Result<Signature, ()> {
279 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
283 impl WriteableEcdsaChannelSigner for TestChannelSigner {}
286 impl TaprootChannelSigner for TestChannelSigner {
287 fn generate_local_nonce_pair(&self, commitment_number: u64, secp_ctx: &Secp256k1<All>) -> PublicNonce {
291 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>), ()> {
295 fn finalize_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, counterparty_partial_signature: PartialSignatureWithNonce, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
299 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, ()> {
303 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, ()> {
307 fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
311 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, ()> {
315 fn partially_sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
319 fn sign_holder_anchor_input(&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
324 impl Writeable for TestChannelSigner {
325 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
326 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
327 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
328 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
329 // and will be serialized as needed by the implementation of that trait.
330 self.inner.write(writer)?;
335 impl TestChannelSigner {
336 fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
337 commitment_tx.verify(
338 &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
339 self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
340 ).expect("derived different per-tx keys or built transaction")
343 fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
344 commitment_tx.verify(
345 &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
346 self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
347 ).expect("derived different per-tx keys or built transaction")
351 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
353 /// This structure is maintained by KeysInterface since we may have multiple copies of
354 /// the signer and they must coordinate their state.
356 pub struct EnforcementState {
357 /// The last counterparty commitment number we signed, backwards counting
358 pub last_counterparty_commitment: u64,
359 /// The last counterparty commitment they revoked, backwards counting
360 pub last_counterparty_revoked_commitment: u64,
361 /// The last holder commitment number we revoked, backwards counting
362 pub last_holder_revoked_commitment: u64,
363 /// The last validated holder commitment number, backwards counting
364 pub last_holder_commitment: u64,
367 impl EnforcementState {
368 /// Enforcement state for a new channel
369 pub fn new() -> Self {
371 last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
372 last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
373 last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
374 last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,