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};
14 use crate::ln::types::PaymentPreimage;
15 use crate::sign::{InMemorySigner, ChannelSigner};
16 use crate::sign::ecdsa::EcdsaChannelSigner;
18 #[allow(unused_imports)]
19 use crate::prelude::*;
22 use crate::sync::{Mutex, Arc};
23 #[cfg(test)] use crate::sync::MutexGuard;
25 use bitcoin::blockdata::transaction::Transaction;
26 use bitcoin::hashes::Hash;
28 use bitcoin::sighash::EcdsaSighashType;
30 use bitcoin::secp256k1;
32 use bitcoin::secp256k1::All;
33 use bitcoin::secp256k1::{SecretKey, PublicKey};
34 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
36 use musig2::types::{PartialSignature, PublicNonce, SecretNonce};
37 use crate::sign::HTLCDescriptor;
38 use crate::util::ser::{Writeable, Writer};
40 use crate::ln::features::ChannelTypeFeatures;
42 use crate::ln::msgs::PartialSignatureWithNonce;
44 use crate::sign::taproot::TaprootChannelSigner;
46 /// Initial value for revoked commitment downward counter
47 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
49 /// An implementation of Sign that enforces some policy checks. The current checks
50 /// are an incomplete set. They include:
52 /// - When signing, the holder transaction has not been revoked
53 /// - When revoking, the holder transaction has not been signed
54 /// - The holder commitment number is monotonic and without gaps
55 /// - The revoked holder commitment number is monotonic and without gaps
56 /// - There is at least one unrevoked holder transaction at all times
57 /// - The counterparty commitment number is monotonic and without gaps
58 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
60 /// Eventually we will probably want to expose a variant of this which would essentially
61 /// be what you'd want to run on a hardware wallet.
63 /// Note that counterparty signatures on the holder transaction are not checked, but it should
64 /// be in a complete implementation.
66 /// Note that before we do so we should ensure its serialization format has backwards- and
67 /// forwards-compatibility prefix/suffixes!
69 pub struct TestChannelSigner {
70 pub inner: InMemorySigner,
71 /// Channel state used for policy enforcement
72 pub state: Arc<Mutex<EnforcementState>>,
73 pub disable_revocation_policy_check: bool,
74 /// When `true` (the default), the signer will respond immediately with signatures. When `false`,
75 /// the signer will return an error indicating that it is unavailable.
76 pub available: Arc<Mutex<bool>>,
79 impl PartialEq for TestChannelSigner {
80 fn eq(&self, o: &Self) -> bool {
81 Arc::ptr_eq(&self.state, &o.state)
85 impl TestChannelSigner {
86 /// Construct an TestChannelSigner
87 pub fn new(inner: InMemorySigner) -> Self {
88 let state = Arc::new(Mutex::new(EnforcementState::new()));
92 disable_revocation_policy_check: false,
93 available: Arc::new(Mutex::new(true)),
97 /// Construct an TestChannelSigner with externally managed storage
99 /// Since there are multiple copies of this struct for each channel, some coordination is needed
100 /// so that all copies are aware of enforcement state. A pointer to this state is provided
101 /// here, usually by an implementation of KeysInterface.
102 pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
106 disable_revocation_policy_check,
107 available: Arc::new(Mutex::new(true)),
111 pub fn channel_type_features(&self) -> &ChannelTypeFeatures { self.inner.channel_type_features().unwrap() }
114 pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
115 self.state.lock().unwrap()
118 /// Marks the signer's availability.
120 /// When `true`, methods are forwarded to the underlying signer as normal. When `false`, some
121 /// methods will return `Err` indicating that the signer is unavailable. Intended to be used for
122 /// testing asynchronous signing.
123 pub fn set_available(&self, available: bool) {
124 *self.available.lock().unwrap() = available;
128 impl ChannelSigner for TestChannelSigner {
129 fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
130 self.inner.get_per_commitment_point(idx, secp_ctx)
133 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
135 let mut state = self.state.lock().unwrap();
136 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);
137 assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
138 state.last_holder_revoked_commitment = idx;
140 self.inner.release_commitment_secret(idx)
143 fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _outbound_htlc_preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
144 let mut state = self.state.lock().unwrap();
145 let idx = holder_tx.commitment_number();
146 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);
147 state.last_holder_commitment = idx;
151 fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
152 if !*self.available.lock().unwrap() {
155 let mut state = self.state.lock().unwrap();
156 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);
157 state.last_counterparty_revoked_commitment = idx;
161 fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
163 fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
165 fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
166 self.inner.provide_channel_parameters(channel_parameters)
170 impl EcdsaChannelSigner for TestChannelSigner {
171 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>), ()> {
172 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
175 if !*self.available.lock().unwrap() {
178 let mut state = self.state.lock().unwrap();
179 let actual_commitment_number = commitment_tx.commitment_number();
180 let last_commitment_number = state.last_counterparty_commitment;
181 // These commitment numbers are backwards counting. We expect either the same as the previously encountered,
183 assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
184 // Ensure that the counterparty doesn't get more than two broadcastable commitments -
185 // the last and the one we are trying to sign
186 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);
187 state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
190 Ok(self.inner.sign_counterparty_commitment(commitment_tx, inbound_htlc_preimages, outbound_htlc_preimages, secp_ctx).unwrap())
193 fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
194 if !*self.available.lock().unwrap() {
197 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
198 let state = self.state.lock().unwrap();
199 let commitment_number = trusted_tx.commitment_number();
200 if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
201 if !self.disable_revocation_policy_check {
202 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
203 state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
206 Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
209 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
210 fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
211 Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
214 fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
215 if !*self.available.lock().unwrap() {
218 Ok(EcdsaChannelSigner::sign_justice_revoked_output(&self.inner, justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
221 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, ()> {
222 if !*self.available.lock().unwrap() {
225 Ok(EcdsaChannelSigner::sign_justice_revoked_htlc(&self.inner, justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
228 fn sign_holder_htlc_transaction(
229 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
230 secp_ctx: &Secp256k1<secp256k1::All>
231 ) -> Result<Signature, ()> {
232 if !*self.available.lock().unwrap() {
235 let state = self.state.lock().unwrap();
236 if state.last_holder_revoked_commitment - 1 != htlc_descriptor.per_commitment_number &&
237 state.last_holder_revoked_commitment - 2 != htlc_descriptor.per_commitment_number
239 if !self.disable_revocation_policy_check {
240 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
241 state.last_holder_revoked_commitment, htlc_descriptor.per_commitment_number, self.inner.commitment_seed[0])
244 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
245 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(secp_ctx));
247 let witness_script = htlc_descriptor.witness_script(secp_ctx);
248 let sighash_type = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
249 EcdsaSighashType::SinglePlusAnyoneCanPay
251 EcdsaSighashType::All
253 let sighash = &sighash::SighashCache::new(&*htlc_tx).p2wsh_signature_hash(
254 input, &witness_script, htlc_descriptor.htlc.to_bitcoin_amount(), sighash_type
256 let countersignatory_htlc_key = HtlcKey::from_basepoint(
257 &secp_ctx, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint, &htlc_descriptor.per_commitment_point,
260 secp_ctx.verify_ecdsa(
261 &hash_to_message!(sighash.as_byte_array()), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key.to_public_key()
264 Ok(EcdsaChannelSigner::sign_holder_htlc_transaction(&self.inner, htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
267 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, ()> {
268 if !*self.available.lock().unwrap() {
271 Ok(EcdsaChannelSigner::sign_counterparty_htlc_transaction(&self.inner, htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
274 fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
275 closing_tx.verify(self.inner.funding_outpoint().unwrap().into_bitcoin_outpoint())
276 .expect("derived different closing transaction");
277 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
280 fn sign_holder_anchor_input(
281 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
282 ) -> Result<Signature, ()> {
283 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
284 // As long as our minimum dust limit is enforced and is greater than our anchor output
285 // value, an anchor output can only have an index within [0, 1].
286 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
287 if !*self.available.lock().unwrap() {
290 EcdsaChannelSigner::sign_holder_anchor_input(&self.inner, anchor_tx, input, secp_ctx)
293 fn sign_channel_announcement_with_funding_key(
294 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
295 ) -> Result<Signature, ()> {
296 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
301 impl TaprootChannelSigner for TestChannelSigner {
302 fn generate_local_nonce_pair(&self, commitment_number: u64, secp_ctx: &Secp256k1<All>) -> PublicNonce {
306 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>), ()> {
310 fn finalize_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, counterparty_partial_signature: PartialSignatureWithNonce, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
314 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, ()> {
318 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, ()> {
322 fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
326 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, ()> {
330 fn partially_sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
334 fn sign_holder_anchor_input(&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
339 impl Writeable for TestChannelSigner {
340 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
341 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
342 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
343 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
344 // and will be serialized as needed by the implementation of that trait.
345 self.inner.write(writer)?;
350 impl TestChannelSigner {
351 fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
352 commitment_tx.verify(
353 &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
354 self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
355 ).expect("derived different per-tx keys or built transaction")
358 fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
359 commitment_tx.verify(
360 &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
361 self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
362 ).expect("derived different per-tx keys or built transaction")
366 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
368 /// This structure is maintained by KeysInterface since we may have multiple copies of
369 /// the signer and they must coordinate their state.
371 pub struct EnforcementState {
372 /// The last counterparty commitment number we signed, backwards counting
373 pub last_counterparty_commitment: u64,
374 /// The last counterparty commitment they revoked, backwards counting
375 pub last_counterparty_revoked_commitment: u64,
376 /// The last holder commitment number we revoked, backwards counting
377 pub last_holder_revoked_commitment: u64,
378 /// The last validated holder commitment number, backwards counting
379 pub last_holder_commitment: u64,
382 impl EnforcementState {
383 /// Enforcement state for a new channel
384 pub fn new() -> Self {
386 last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
387 last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
388 last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
389 last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,