_ Git - rust-lightning/blob - lightning/src/util/test_channel_signer.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   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
   8 // licenses.
   9
  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::{WriteableEcdsaChannelSigner, InMemorySigner, ChannelSigner, EcdsaChannelSigner};
  15
  16 use crate::prelude::*;
  17 use core::cmp;
  18 use crate::sync::{Mutex, Arc};
  19 #[cfg(test)] use crate::sync::MutexGuard;
  20
  21 use bitcoin::blockdata::transaction::Transaction;
  22 use bitcoin::hashes::Hash;
  23 use bitcoin::sighash;
  24 use bitcoin::sighash::EcdsaSighashType;
  25
  26 use bitcoin::secp256k1;
  27 #[cfg(taproot)]
  28 use bitcoin::secp256k1::All;
  29 use bitcoin::secp256k1::{SecretKey, PublicKey};
  30 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
  31 #[cfg(taproot)]
  32 use musig2::types::{PartialSignature, PublicNonce, SecretNonce};
  33 use crate::sign::HTLCDescriptor;
  34 use crate::util::ser::{Writeable, Writer};
  35 use crate::io::Error;
  36 use crate::ln::features::ChannelTypeFeatures;
  37 #[cfg(taproot)]
  38 use crate::ln::msgs::PartialSignatureWithNonce;
  39 #[cfg(taproot)]
  40 use crate::sign::taproot::TaprootChannelSigner;
  41
  42 /// Initial value for revoked commitment downward counter
  43 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
  44
  45 /// An implementation of Sign that enforces some policy checks.  The current checks
  46 /// are an incomplete set.  They include:
  47 ///
  48 /// - When signing, the holder transaction has not been revoked
  49 /// - When revoking, the holder transaction has not been signed
  50 /// - The holder commitment number is monotonic and without gaps
  51 /// - The revoked holder commitment number is monotonic and without gaps
  52 /// - There is at least one unrevoked holder transaction at all times
  53 /// - The counterparty commitment number is monotonic and without gaps
  54 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
  55 ///
  56 /// Eventually we will probably want to expose a variant of this which would essentially
  57 /// be what you'd want to run on a hardware wallet.
  58 ///
  59 /// Note that counterparty signatures on the holder transaction are not checked, but it should
  60 /// be in a complete implementation.
  61 ///
  62 /// Note that before we do so we should ensure its serialization format has backwards- and
  63 /// forwards-compatibility prefix/suffixes!
  64 #[derive(Clone)]
  65 pub struct TestChannelSigner {
  66         pub inner: InMemorySigner,
  67         /// Channel state used for policy enforcement
  68         pub state: Arc<Mutex<EnforcementState>>,
  69         pub disable_revocation_policy_check: bool,
  70         /// When `true` (the default), the signer will respond immediately with signatures. When `false`,
  71         /// the signer will return an error indicating that it is unavailable.
  72         pub available: Arc<Mutex<bool>>,
  73 }
  74
  75 impl PartialEq for TestChannelSigner {
  76         fn eq(&self, o: &Self) -> bool {
  77                 Arc::ptr_eq(&self.state, &o.state)
  78         }
  79 }
  80
  81 impl TestChannelSigner {
  82         /// Construct an TestChannelSigner
  83         pub fn new(inner: InMemorySigner) -> Self {
  84                 let state = Arc::new(Mutex::new(EnforcementState::new()));
  85                 Self {
  86                         inner,
  87                         state,
  88                         disable_revocation_policy_check: false,
  89                         available: Arc::new(Mutex::new(true)),
  90                 }
  91         }
  92
  93         /// Construct an TestChannelSigner with externally managed storage
  94         ///
  95         /// Since there are multiple copies of this struct for each channel, some coordination is needed
  96         /// so that all copies are aware of enforcement state.  A pointer to this state is provided
  97         /// here, usually by an implementation of KeysInterface.
  98         pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
  99                 Self {
 100                         inner,
 101                         state,
 102                         disable_revocation_policy_check,
 103                         available: Arc::new(Mutex::new(true)),
 104                 }
 105         }
 106
 107         pub fn channel_type_features(&self) -> &ChannelTypeFeatures { self.inner.channel_type_features().unwrap() }
 108
 109         #[cfg(test)]
 110         pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
 111                 self.state.lock().unwrap()
 112         }
 113
 114         /// Marks the signer's availability.
 115         ///
 116         /// When `true`, methods are forwarded to the underlying signer as normal. When `false`, some
 117         /// methods will return `Err` indicating that the signer is unavailable. Intended to be used for
 118         /// testing asynchronous signing.
 119         #[cfg(test)]
 120         pub fn set_available(&self, available: bool) {
 121                 *self.available.lock().unwrap() = available;
 122         }
 123 }
 124
 125 impl ChannelSigner for TestChannelSigner {
 126         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
 127                 self.inner.get_per_commitment_point(idx, secp_ctx)
 128         }
 129
 130         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
 131                 {
 132                         let mut state = self.state.lock().unwrap();
 133                         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);
 134                         assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
 135                         state.last_holder_revoked_commitment = idx;
 136                 }
 137                 self.inner.release_commitment_secret(idx)
 138         }
 139
 140         fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
 141                 let mut state = self.state.lock().unwrap();
 142                 let idx = holder_tx.commitment_number();
 143                 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);
 144                 state.last_holder_commitment = idx;
 145                 Ok(())
 146         }
 147
 148         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
 149
 150         fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
 151
 152         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
 153                 self.inner.provide_channel_parameters(channel_parameters)
 154         }
 155 }
 156
 157 impl EcdsaChannelSigner for TestChannelSigner {
 158         fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 159                 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
 160
 161                 {
 162                         if !*self.available.lock().unwrap() {
 163                                 return Err(());
 164                         }
 165                         let mut state = self.state.lock().unwrap();
 166                         let actual_commitment_number = commitment_tx.commitment_number();
 167                         let last_commitment_number = state.last_counterparty_commitment;
 168                         // These commitment numbers are backwards counting.  We expect either the same as the previously encountered,
 169                         // or the next one.
 170                         assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
 171                         // Ensure that the counterparty doesn't get more than two broadcastable commitments -
 172                         // the last and the one we are trying to sign
 173                         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);
 174                         state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
 175                 }
 176
 177                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, preimages, secp_ctx).unwrap())
 178         }
 179
 180         fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
 181                 if !*self.available.lock().unwrap() {
 182                         return Err(());
 183                 }
 184                 let mut state = self.state.lock().unwrap();
 185                 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);
 186                 state.last_counterparty_revoked_commitment = idx;
 187                 Ok(())
 188         }
 189
 190         fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 191                 if !*self.available.lock().unwrap() {
 192                         return Err(());
 193                 }
 194                 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
 195                 let state = self.state.lock().unwrap();
 196                 let commitment_number = trusted_tx.commitment_number();
 197                 if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
 198                         if !self.disable_revocation_policy_check {
 199                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 200                                        state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
 201                         }
 202                 }
 203                 Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 204         }
 205
 206         #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
 207         fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 208                 Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 209         }
 210
 211         fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 212                 Ok(EcdsaChannelSigner::sign_justice_revoked_output(&self.inner, justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
 213         }
 214
 215         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, ()> {
 216                 Ok(EcdsaChannelSigner::sign_justice_revoked_htlc(&self.inner, justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
 217         }
 218
 219         fn sign_holder_htlc_transaction(
 220                 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
 221                 secp_ctx: &Secp256k1<secp256k1::All>
 222         ) -> Result<Signature, ()> {
 223                 let state = self.state.lock().unwrap();
 224                 if state.last_holder_revoked_commitment - 1 != htlc_descriptor.per_commitment_number &&
 225                         state.last_holder_revoked_commitment - 2 != htlc_descriptor.per_commitment_number
 226                 {
 227                         if !self.disable_revocation_policy_check {
 228                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 229                                        state.last_holder_revoked_commitment, htlc_descriptor.per_commitment_number, self.inner.commitment_seed[0])
 230                         }
 231                 }
 232                 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
 233                 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(secp_ctx));
 234                 {
 235                         let witness_script = htlc_descriptor.witness_script(secp_ctx);
 236                         let sighash_type = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
 237                                 EcdsaSighashType::SinglePlusAnyoneCanPay
 238                         } else {
 239                                 EcdsaSighashType::All
 240                         };
 241                         let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
 242                                 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, sighash_type
 243                         ).unwrap();
 244                         let countersignatory_htlc_key = HtlcKey::from_basepoint(
 245                                 &secp_ctx, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint, &htlc_descriptor.per_commitment_point,
 246                         );
 247
 248                         secp_ctx.verify_ecdsa(
 249                                 &hash_to_message!(sighash.as_byte_array()), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key.to_public_key()
 250                         ).unwrap();
 251                 }
 252                 Ok(EcdsaChannelSigner::sign_holder_htlc_transaction(&self.inner, htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
 253         }
 254
 255         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, ()> {
 256                 Ok(EcdsaChannelSigner::sign_counterparty_htlc_transaction(&self.inner, htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
 257         }
 258
 259         fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 260                 closing_tx.verify(self.inner.funding_outpoint().unwrap().into_bitcoin_outpoint())
 261                         .expect("derived different closing transaction");
 262                 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
 263         }
 264
 265         fn sign_holder_anchor_input(
 266                 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
 267         ) -> Result<Signature, ()> {
 268                 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
 269                 // As long as our minimum dust limit is enforced and is greater than our anchor output
 270                 // value, an anchor output can only have an index within [0, 1].
 271                 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
 272                 EcdsaChannelSigner::sign_holder_anchor_input(&self.inner, anchor_tx, input, secp_ctx)
 273         }
 274
 275         fn sign_channel_announcement_with_funding_key(
 276                 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
 277         ) -> Result<Signature, ()> {
 278                 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
 279         }
 280 }
 281
 282 impl WriteableEcdsaChannelSigner for TestChannelSigner {}
 283
 284 #[cfg(taproot)]
 285 impl TaprootChannelSigner for TestChannelSigner {
 286         fn generate_local_nonce_pair(&self, commitment_number: u64, secp_ctx: &Secp256k1<All>) -> PublicNonce {
 287                 todo!()
 288         }
 289
 290         fn partially_sign_counterparty_commitment(&self, counterparty_nonce: PublicNonce, commitment_tx: &CommitmentTransaction, preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<All>) -> Result<(PartialSignatureWithNonce, Vec<secp256k1::schnorr::Signature>), ()> {
 291                 todo!()
 292         }
 293
 294         fn finalize_holder_commitment(&self, commitment_number: u64, commitment_tx: &HolderCommitmentTransaction, counterparty_partial_signature: PartialSignatureWithNonce, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
 295                 todo!()
 296         }
 297
 298         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, ()> {
 299                 todo!()
 300         }
 301
 302         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, ()> {
 303                 todo!()
 304         }
 305
 306         fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
 307                 todo!()
 308         }
 309
 310         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, ()> {
 311                 todo!()
 312         }
 313
 314         fn partially_sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
 315                 todo!()
 316         }
 317
 318         fn sign_holder_anchor_input(&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
 319                 todo!()
 320         }
 321 }
 322
 323 impl Writeable for TestChannelSigner {
 324         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 325                 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
 326                 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
 327                 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
 328                 // and will be serialized as needed by the implementation of that trait.
 329                 self.inner.write(writer)?;
 330                 Ok(())
 331         }
 332 }
 333
 334 impl TestChannelSigner {
 335         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 336                 commitment_tx.verify(
 337                         &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
 338                         self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
 339                 ).expect("derived different per-tx keys or built transaction")
 340         }
 341
 342         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 343                 commitment_tx.verify(
 344                         &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
 345                         self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
 346                 ).expect("derived different per-tx keys or built transaction")
 347         }
 348 }
 349
 350 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
 351 ///
 352 /// This structure is maintained by KeysInterface since we may have multiple copies of
 353 /// the signer and they must coordinate their state.
 354 #[derive(Clone)]
 355 pub struct EnforcementState {
 356         /// The last counterparty commitment number we signed, backwards counting
 357         pub last_counterparty_commitment: u64,
 358         /// The last counterparty commitment they revoked, backwards counting
 359         pub last_counterparty_revoked_commitment: u64,
 360         /// The last holder commitment number we revoked, backwards counting
 361         pub last_holder_revoked_commitment: u64,
 362         /// The last validated holder commitment number, backwards counting
 363         pub last_holder_commitment: u64,
 364 }
 365
 366 impl EnforcementState {
 367         /// Enforcement state for a new channel
 368         pub fn new() -> Self {
 369                 EnforcementState {
 370                         last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 371                         last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 372                         last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 373                         last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 374                 }
 375         }
 376 }