_ 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::{InMemorySigner, ChannelSigner};
  15 use crate::sign::ecdsa::{EcdsaChannelSigner, WriteableEcdsaChannelSigner};
  16
  17 use crate::prelude::*;
  18 use core::cmp;
  19 use crate::sync::{Mutex, Arc};
  20 #[cfg(test)] use crate::sync::MutexGuard;
  21
  22 use bitcoin::blockdata::transaction::Transaction;
  23 use bitcoin::hashes::Hash;
  24 use bitcoin::sighash;
  25 use bitcoin::sighash::EcdsaSighashType;
  26
  27 use bitcoin::secp256k1;
  28 #[cfg(taproot)]
  29 use bitcoin::secp256k1::All;
  30 use bitcoin::secp256k1::{SecretKey, PublicKey};
  31 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
  32 #[cfg(taproot)]
  33 use musig2::types::{PartialSignature, PublicNonce, SecretNonce};
  34 use crate::sign::HTLCDescriptor;
  35 use crate::util::ser::{Writeable, Writer};
  36 use crate::io::Error;
  37 use crate::ln::features::ChannelTypeFeatures;
  38 #[cfg(taproot)]
  39 use crate::ln::msgs::PartialSignatureWithNonce;
  40 #[cfg(taproot)]
  41 use crate::sign::taproot::TaprootChannelSigner;
  42
  43 /// Initial value for revoked commitment downward counter
  44 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
  45
  46 /// An implementation of Sign that enforces some policy checks.  The current checks
  47 /// are an incomplete set.  They include:
  48 ///
  49 /// - When signing, the holder transaction has not been revoked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
  56 ///
  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.
  59 ///
  60 /// Note that counterparty signatures on the holder transaction are not checked, but it should
  61 /// be in a complete implementation.
  62 ///
  63 /// Note that before we do so we should ensure its serialization format has backwards- and
  64 /// forwards-compatibility prefix/suffixes!
  65 #[derive(Clone)]
  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>>,
  74 }
  75
  76 impl PartialEq for TestChannelSigner {
  77         fn eq(&self, o: &Self) -> bool {
  78                 Arc::ptr_eq(&self.state, &o.state)
  79         }
  80 }
  81
  82 impl TestChannelSigner {
  83         /// Construct an TestChannelSigner
  84         pub fn new(inner: InMemorySigner) -> Self {
  85                 let state = Arc::new(Mutex::new(EnforcementState::new()));
  86                 Self {
  87                         inner,
  88                         state,
  89                         disable_revocation_policy_check: false,
  90                         available: Arc::new(Mutex::new(true)),
  91                 }
  92         }
  93
  94         /// Construct an TestChannelSigner with externally managed storage
  95         ///
  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 {
 100                 Self {
 101                         inner,
 102                         state,
 103                         disable_revocation_policy_check,
 104                         available: Arc::new(Mutex::new(true)),
 105                 }
 106         }
 107
 108         pub fn channel_type_features(&self) -> &ChannelTypeFeatures { self.inner.channel_type_features().unwrap() }
 109
 110         #[cfg(test)]
 111         pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
 112                 self.state.lock().unwrap()
 113         }
 114
 115         /// Marks the signer's availability.
 116         ///
 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.
 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, _outbound_htlc_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 validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
 149                 if !*self.available.lock().unwrap() {
 150                         return Err(());
 151                 }
 152                 let mut state = self.state.lock().unwrap();
 153                 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);
 154                 state.last_counterparty_revoked_commitment = idx;
 155                 Ok(())
 156         }
 157
 158         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
 159
 160         fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
 161
 162         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
 163                 self.inner.provide_channel_parameters(channel_parameters)
 164         }
 165 }
 166
 167 impl EcdsaChannelSigner for TestChannelSigner {
 168         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>), ()> {
 169                 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
 170
 171                 {
 172                         if !*self.available.lock().unwrap() {
 173                                 return Err(());
 174                         }
 175                         let mut state = self.state.lock().unwrap();
 176                         let actual_commitment_number = commitment_tx.commitment_number();
 177                         let last_commitment_number = state.last_counterparty_commitment;
 178                         // These commitment numbers are backwards counting.  We expect either the same as the previously encountered,
 179                         // or the next one.
 180                         assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
 181                         // Ensure that the counterparty doesn't get more than two broadcastable commitments -
 182                         // the last and the one we are trying to sign
 183                         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);
 184                         state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
 185                 }
 186
 187                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, inbound_htlc_preimages, outbound_htlc_preimages, secp_ctx).unwrap())
 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                 if !*self.available.lock().unwrap() {
 213                         return Err(());
 214                 }
 215                 Ok(EcdsaChannelSigner::sign_justice_revoked_output(&self.inner, justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
 216         }
 217
 218         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, ()> {
 219                 if !*self.available.lock().unwrap() {
 220                         return Err(());
 221                 }
 222                 Ok(EcdsaChannelSigner::sign_justice_revoked_htlc(&self.inner, justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
 223         }
 224
 225         fn sign_holder_htlc_transaction(
 226                 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
 227                 secp_ctx: &Secp256k1<secp256k1::All>
 228         ) -> Result<Signature, ()> {
 229                 if !*self.available.lock().unwrap() {
 230                         return Err(());
 231                 }
 232                 let state = self.state.lock().unwrap();
 233                 if state.last_holder_revoked_commitment - 1 != htlc_descriptor.per_commitment_number &&
 234                         state.last_holder_revoked_commitment - 2 != htlc_descriptor.per_commitment_number
 235                 {
 236                         if !self.disable_revocation_policy_check {
 237                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 238                                        state.last_holder_revoked_commitment, htlc_descriptor.per_commitment_number, self.inner.commitment_seed[0])
 239                         }
 240                 }
 241                 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
 242                 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(secp_ctx));
 243                 {
 244                         let witness_script = htlc_descriptor.witness_script(secp_ctx);
 245                         let sighash_type = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
 246                                 EcdsaSighashType::SinglePlusAnyoneCanPay
 247                         } else {
 248                                 EcdsaSighashType::All
 249                         };
 250                         let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
 251                                 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, sighash_type
 252                         ).unwrap();
 253                         let countersignatory_htlc_key = HtlcKey::from_basepoint(
 254                                 &secp_ctx, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint, &htlc_descriptor.per_commitment_point,
 255                         );
 256
 257                         secp_ctx.verify_ecdsa(
 258                                 &hash_to_message!(sighash.as_byte_array()), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key.to_public_key()
 259                         ).unwrap();
 260                 }
 261                 Ok(EcdsaChannelSigner::sign_holder_htlc_transaction(&self.inner, htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
 262         }
 263
 264         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, ()> {
 265                 if !*self.available.lock().unwrap() {
 266                         return Err(());
 267                 }
 268                 Ok(EcdsaChannelSigner::sign_counterparty_htlc_transaction(&self.inner, htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
 269         }
 270
 271         fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 272                 closing_tx.verify(self.inner.funding_outpoint().unwrap().into_bitcoin_outpoint())
 273                         .expect("derived different closing transaction");
 274                 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
 275         }
 276
 277         fn sign_holder_anchor_input(
 278                 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
 279         ) -> Result<Signature, ()> {
 280                 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
 281                 // As long as our minimum dust limit is enforced and is greater than our anchor output
 282                 // value, an anchor output can only have an index within [0, 1].
 283                 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
 284                 if !*self.available.lock().unwrap() {
 285                         return Err(());
 286                 }
 287                 EcdsaChannelSigner::sign_holder_anchor_input(&self.inner, anchor_tx, input, secp_ctx)
 288         }
 289
 290         fn sign_channel_announcement_with_funding_key(
 291                 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
 292         ) -> Result<Signature, ()> {
 293                 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
 294         }
 295 }
 296
 297 impl WriteableEcdsaChannelSigner for TestChannelSigner {}
 298
 299 #[cfg(taproot)]
 300 impl TaprootChannelSigner for TestChannelSigner {
 301         fn generate_local_nonce_pair(&self, commitment_number: u64, secp_ctx: &Secp256k1<All>) -> PublicNonce {
 302                 todo!()
 303         }
 304
 305         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>), ()> {
 306                 todo!()
 307         }
 308
 309         fn finalize_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, counterparty_partial_signature: PartialSignatureWithNonce, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
 310                 todo!()
 311         }
 312
 313         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, ()> {
 314                 todo!()
 315         }
 316
 317         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, ()> {
 318                 todo!()
 319         }
 320
 321         fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
 322                 todo!()
 323         }
 324
 325         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, ()> {
 326                 todo!()
 327         }
 328
 329         fn partially_sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
 330                 todo!()
 331         }
 332
 333         fn sign_holder_anchor_input(&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
 334                 todo!()
 335         }
 336 }
 337
 338 impl Writeable for TestChannelSigner {
 339         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 340                 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
 341                 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
 342                 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
 343                 // and will be serialized as needed by the implementation of that trait.
 344                 self.inner.write(writer)?;
 345                 Ok(())
 346         }
 347 }
 348
 349 impl TestChannelSigner {
 350         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 351                 commitment_tx.verify(
 352                         &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
 353                         self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
 354                 ).expect("derived different per-tx keys or built transaction")
 355         }
 356
 357         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 358                 commitment_tx.verify(
 359                         &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
 360                         self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
 361                 ).expect("derived different per-tx keys or built transaction")
 362         }
 363 }
 364
 365 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
 366 ///
 367 /// This structure is maintained by KeysInterface since we may have multiple copies of
 368 /// the signer and they must coordinate their state.
 369 #[derive(Clone)]
 370 pub struct EnforcementState {
 371         /// The last counterparty commitment number we signed, backwards counting
 372         pub last_counterparty_commitment: u64,
 373         /// The last counterparty commitment they revoked, backwards counting
 374         pub last_counterparty_revoked_commitment: u64,
 375         /// The last holder commitment number we revoked, backwards counting
 376         pub last_holder_revoked_commitment: u64,
 377         /// The last validated holder commitment number, backwards counting
 378         pub last_holder_commitment: u64,
 379 }
 380
 381 impl EnforcementState {
 382         /// Enforcement state for a new channel
 383         pub fn new() -> Self {
 384                 EnforcementState {
 385                         last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 386                         last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 387                         last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 388                         last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 389                 }
 390         }
 391 }