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::{chan_utils, msgs, PaymentPreimage};
13 use crate::sign::{WriteableEcdsaChannelSigner, InMemorySigner, ChannelSigner, EcdsaChannelSigner};
15 use crate::prelude::*;
17 use crate::sync::{Mutex, Arc};
18 #[cfg(test)] use crate::sync::MutexGuard;
20 use bitcoin::blockdata::transaction::{Transaction, EcdsaSighashType};
21 use bitcoin::util::sighash;
23 use bitcoin::secp256k1;
24 use bitcoin::secp256k1::{SecretKey, PublicKey};
25 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
26 use crate::sign::HTLCDescriptor;
27 use crate::util::ser::{Writeable, Writer};
29 use crate::ln::features::ChannelTypeFeatures;
31 /// Initial value for revoked commitment downward counter
32 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
34 /// An implementation of Sign that enforces some policy checks. The current checks
35 /// are an incomplete set. They include:
37 /// - When signing, the holder transaction has not been revoked
38 /// - When revoking, the holder transaction has not been signed
39 /// - The holder commitment number is monotonic and without gaps
40 /// - The revoked holder commitment number is monotonic and without gaps
41 /// - There is at least one unrevoked holder transaction at all times
42 /// - The counterparty commitment number is monotonic and without gaps
43 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
45 /// Eventually we will probably want to expose a variant of this which would essentially
46 /// be what you'd want to run on a hardware wallet.
48 /// Note that counterparty signatures on the holder transaction are not checked, but it should
49 /// be in a complete implementation.
51 /// Note that before we do so we should ensure its serialization format has backwards- and
52 /// forwards-compatibility prefix/suffixes!
54 pub struct TestChannelSigner {
55 pub inner: InMemorySigner,
56 /// Channel state used for policy enforcement
57 pub state: Arc<Mutex<EnforcementState>>,
58 pub disable_revocation_policy_check: bool,
59 /// When `true` (the default), the signer will respond immediately with signatures. When `false`,
60 /// the signer will return an error indicating that it is unavailable.
61 pub available: Arc<Mutex<bool>>,
64 impl PartialEq for TestChannelSigner {
65 fn eq(&self, o: &Self) -> bool {
66 Arc::ptr_eq(&self.state, &o.state)
70 impl TestChannelSigner {
71 /// Construct an TestChannelSigner
72 pub fn new(inner: InMemorySigner) -> Self {
73 let state = Arc::new(Mutex::new(EnforcementState::new()));
77 disable_revocation_policy_check: false,
78 available: Arc::new(Mutex::new(true)),
82 /// Construct an TestChannelSigner with externally managed storage
84 /// Since there are multiple copies of this struct for each channel, some coordination is needed
85 /// so that all copies are aware of enforcement state. A pointer to this state is provided
86 /// here, usually by an implementation of KeysInterface.
87 pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
91 disable_revocation_policy_check,
92 available: Arc::new(Mutex::new(true)),
96 pub fn channel_type_features(&self) -> &ChannelTypeFeatures { self.inner.channel_type_features().unwrap() }
99 pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
100 self.state.lock().unwrap()
103 /// Marks the signer's availability.
105 /// When `true`, methods are forwarded to the underlying signer as normal. When `false`, some
106 /// methods will return `Err` indicating that the signer is unavailable. Intended to be used for
107 /// testing asynchronous signing.
109 pub fn set_available(&self, available: bool) {
110 *self.available.lock().unwrap() = available;
114 impl ChannelSigner for TestChannelSigner {
115 fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
116 self.inner.get_per_commitment_point(idx, secp_ctx)
119 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
121 let mut state = self.state.lock().unwrap();
122 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);
123 assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
124 state.last_holder_revoked_commitment = idx;
126 self.inner.release_commitment_secret(idx)
129 fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
130 let mut state = self.state.lock().unwrap();
131 let idx = holder_tx.commitment_number();
132 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);
133 state.last_holder_commitment = idx;
137 fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
139 fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
141 fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
142 self.inner.provide_channel_parameters(channel_parameters)
146 impl EcdsaChannelSigner for TestChannelSigner {
147 fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
148 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
151 if !*self.available.lock().unwrap() {
154 let mut state = self.state.lock().unwrap();
155 let actual_commitment_number = commitment_tx.commitment_number();
156 let last_commitment_number = state.last_counterparty_commitment;
157 // These commitment numbers are backwards counting. We expect either the same as the previously encountered,
159 assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
160 // Ensure that the counterparty doesn't get more than two broadcastable commitments -
161 // the last and the one we are trying to sign
162 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);
163 state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
166 Ok(self.inner.sign_counterparty_commitment(commitment_tx, preimages, secp_ctx).unwrap())
169 fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
170 if !*self.available.lock().unwrap() {
173 let mut state = self.state.lock().unwrap();
174 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);
175 state.last_counterparty_revoked_commitment = idx;
179 fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
180 if !*self.available.lock().unwrap() {
183 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
184 let state = self.state.lock().unwrap();
185 let commitment_number = trusted_tx.commitment_number();
186 if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
187 if !self.disable_revocation_policy_check {
188 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
189 state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
192 Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
195 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
196 fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
197 Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
200 fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
201 Ok(self.inner.sign_justice_revoked_output(justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
204 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, ()> {
205 Ok(self.inner.sign_justice_revoked_htlc(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
208 fn sign_holder_htlc_transaction(
209 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
210 secp_ctx: &Secp256k1<secp256k1::All>
211 ) -> Result<Signature, ()> {
212 let state = self.state.lock().unwrap();
213 if state.last_holder_revoked_commitment - 1 != htlc_descriptor.per_commitment_number &&
214 state.last_holder_revoked_commitment - 2 != htlc_descriptor.per_commitment_number
216 if !self.disable_revocation_policy_check {
217 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
218 state.last_holder_revoked_commitment, htlc_descriptor.per_commitment_number, self.inner.commitment_seed[0])
221 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
222 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(secp_ctx));
224 let witness_script = htlc_descriptor.witness_script(secp_ctx);
225 let sighash_type = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
226 EcdsaSighashType::SinglePlusAnyoneCanPay
228 EcdsaSighashType::All
230 let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
231 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, sighash_type
233 let countersignatory_htlc_key = chan_utils::derive_public_key(
234 &secp_ctx, &htlc_descriptor.per_commitment_point, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint
236 secp_ctx.verify_ecdsa(
237 &hash_to_message!(&sighash), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key
240 Ok(self.inner.sign_holder_htlc_transaction(htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
243 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, ()> {
244 Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
247 fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
248 closing_tx.verify(self.inner.funding_outpoint().unwrap().into_bitcoin_outpoint())
249 .expect("derived different closing transaction");
250 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
253 fn sign_holder_anchor_input(
254 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
255 ) -> Result<Signature, ()> {
256 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
257 // As long as our minimum dust limit is enforced and is greater than our anchor output
258 // value, an anchor output can only have an index within [0, 1].
259 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
260 self.inner.sign_holder_anchor_input(anchor_tx, input, secp_ctx)
263 fn sign_channel_announcement_with_funding_key(
264 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
265 ) -> Result<Signature, ()> {
266 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
270 impl WriteableEcdsaChannelSigner for TestChannelSigner {}
272 impl Writeable for TestChannelSigner {
273 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
274 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
275 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
276 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
277 // and will be serialized as needed by the implementation of that trait.
278 self.inner.write(writer)?;
283 impl TestChannelSigner {
284 fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
285 commitment_tx.verify(
286 &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
287 self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
288 ).expect("derived different per-tx keys or built transaction")
291 fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
292 commitment_tx.verify(
293 &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
294 self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
295 ).expect("derived different per-tx keys or built transaction")
299 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
301 /// This structure is maintained by KeysInterface since we may have multiple copies of
302 /// the signer and they must coordinate their state.
304 pub struct EnforcementState {
305 /// The last counterparty commitment number we signed, backwards counting
306 pub last_counterparty_commitment: u64,
307 /// The last counterparty commitment they revoked, backwards counting
308 pub last_counterparty_revoked_commitment: u64,
309 /// The last holder commitment number we revoked, backwards counting
310 pub last_holder_revoked_commitment: u64,
311 /// The last validated holder commitment number, backwards counting
312 pub last_holder_commitment: u64,
315 impl EnforcementState {
316 /// Enforcement state for a new channel
317 pub fn new() -> Self {
319 last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
320 last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
321 last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
322 last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,