_ 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 #[allow(unused_imports)]
  18 use crate::prelude::*;
  19
  20 use core::cmp;
  21 use crate::sync::{Mutex, Arc};
  22 #[cfg(test)] use crate::sync::MutexGuard;
  23
  24 use bitcoin::blockdata::transaction::Transaction;
  25 use bitcoin::hashes::Hash;
  26 use bitcoin::sighash;
  27 use bitcoin::sighash::EcdsaSighashType;
  28
  29 use bitcoin::secp256k1;
  30 #[cfg(taproot)]
  31 use bitcoin::secp256k1::All;
  32 use bitcoin::secp256k1::{SecretKey, PublicKey};
  33 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
  34 #[cfg(taproot)]
  35 use musig2::types::{PartialSignature, PublicNonce, SecretNonce};
  36 use crate::sign::HTLCDescriptor;
  37 use crate::util::ser::{Writeable, Writer};
  38 use crate::io::Error;
  39 use crate::ln::features::ChannelTypeFeatures;
  40 #[cfg(taproot)]
  41 use crate::ln::msgs::PartialSignatureWithNonce;
  42 #[cfg(taproot)]
  43 use crate::sign::taproot::TaprootChannelSigner;
  44
  45 /// Initial value for revoked commitment downward counter
  46 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
  47
  48 /// An implementation of Sign that enforces some policy checks.  The current checks
  49 /// are an incomplete set.  They include:
  50 ///
  51 /// - When signing, the holder transaction has not been revoked
  52 /// - When revoking, the holder transaction has not been signed
  53 /// - The holder commitment number is monotonic and without gaps
  54 /// - The revoked holder commitment number is monotonic and without gaps
  55 /// - There is at least one unrevoked holder transaction at all times
  56 /// - The counterparty commitment number is monotonic and without gaps
  57 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
  58 ///
  59 /// Eventually we will probably want to expose a variant of this which would essentially
  60 /// be what you'd want to run on a hardware wallet.
  61 ///
  62 /// Note that counterparty signatures on the holder transaction are not checked, but it should
  63 /// be in a complete implementation.
  64 ///
  65 /// Note that before we do so we should ensure its serialization format has backwards- and
  66 /// forwards-compatibility prefix/suffixes!
  67 #[derive(Clone)]
  68 pub struct TestChannelSigner {
  69         pub inner: InMemorySigner,
  70         /// Channel state used for policy enforcement
  71         pub state: Arc<Mutex<EnforcementState>>,
  72         pub disable_revocation_policy_check: bool,
  73         /// When `true` (the default), the signer will respond immediately with signatures. When `false`,
  74         /// the signer will return an error indicating that it is unavailable.
  75         pub available: Arc<Mutex<bool>>,
  76 }
  77
  78 impl PartialEq for TestChannelSigner {
  79         fn eq(&self, o: &Self) -> bool {
  80                 Arc::ptr_eq(&self.state, &o.state)
  81         }
  82 }
  83
  84 impl TestChannelSigner {
  85         /// Construct an TestChannelSigner
  86         pub fn new(inner: InMemorySigner) -> Self {
  87                 let state = Arc::new(Mutex::new(EnforcementState::new()));
  88                 Self {
  89                         inner,
  90                         state,
  91                         disable_revocation_policy_check: false,
  92                         available: Arc::new(Mutex::new(true)),
  93                 }
  94         }
  95
  96         /// Construct an TestChannelSigner with externally managed storage
  97         ///
  98         /// Since there are multiple copies of this struct for each channel, some coordination is needed
  99         /// so that all copies are aware of enforcement state.  A pointer to this state is provided
 100         /// here, usually by an implementation of KeysInterface.
 101         pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
 102                 Self {
 103                         inner,
 104                         state,
 105                         disable_revocation_policy_check,
 106                         available: Arc::new(Mutex::new(true)),
 107                 }
 108         }
 109
 110         pub fn channel_type_features(&self) -> &ChannelTypeFeatures { self.inner.channel_type_features().unwrap() }
 111
 112         #[cfg(test)]
 113         pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
 114                 self.state.lock().unwrap()
 115         }
 116
 117         /// Marks the signer's availability.
 118         ///
 119         /// When `true`, methods are forwarded to the underlying signer as normal. When `false`, some
 120         /// methods will return `Err` indicating that the signer is unavailable. Intended to be used for
 121         /// testing asynchronous signing.
 122         pub fn set_available(&self, available: bool) {
 123                 *self.available.lock().unwrap() = available;
 124         }
 125 }
 126
 127 impl ChannelSigner for TestChannelSigner {
 128         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
 129                 self.inner.get_per_commitment_point(idx, secp_ctx)
 130         }
 131
 132         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
 133                 {
 134                         let mut state = self.state.lock().unwrap();
 135                         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);
 136                         assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
 137                         state.last_holder_revoked_commitment = idx;
 138                 }
 139                 self.inner.release_commitment_secret(idx)
 140         }
 141
 142         fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _outbound_htlc_preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
 143                 let mut state = self.state.lock().unwrap();
 144                 let idx = holder_tx.commitment_number();
 145                 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);
 146                 state.last_holder_commitment = idx;
 147                 Ok(())
 148         }
 149
 150         fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
 151                 if !*self.available.lock().unwrap() {
 152                         return Err(());
 153                 }
 154                 let mut state = self.state.lock().unwrap();
 155                 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);
 156                 state.last_counterparty_revoked_commitment = idx;
 157                 Ok(())
 158         }
 159
 160         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
 161
 162         fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
 163
 164         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
 165                 self.inner.provide_channel_parameters(channel_parameters)
 166         }
 167 }
 168
 169 impl EcdsaChannelSigner for TestChannelSigner {
 170         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>), ()> {
 171                 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
 172
 173                 {
 174                         if !*self.available.lock().unwrap() {
 175                                 return Err(());
 176                         }
 177                         let mut state = self.state.lock().unwrap();
 178                         let actual_commitment_number = commitment_tx.commitment_number();
 179                         let last_commitment_number = state.last_counterparty_commitment;
 180                         // These commitment numbers are backwards counting.  We expect either the same as the previously encountered,
 181                         // or the next one.
 182                         assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
 183                         // Ensure that the counterparty doesn't get more than two broadcastable commitments -
 184                         // the last and the one we are trying to sign
 185                         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);
 186                         state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
 187                 }
 188
 189                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, inbound_htlc_preimages, outbound_htlc_preimages, secp_ctx).unwrap())
 190         }
 191
 192         fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 193                 if !*self.available.lock().unwrap() {
 194                         return Err(());
 195                 }
 196                 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
 197                 let state = self.state.lock().unwrap();
 198                 let commitment_number = trusted_tx.commitment_number();
 199                 if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
 200                         if !self.disable_revocation_policy_check {
 201                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 202                                        state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
 203                         }
 204                 }
 205                 Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 206         }
 207
 208         #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
 209         fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 210                 Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 211         }
 212
 213         fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 214                 if !*self.available.lock().unwrap() {
 215                         return Err(());
 216                 }
 217                 Ok(EcdsaChannelSigner::sign_justice_revoked_output(&self.inner, justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
 218         }
 219
 220         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, ()> {
 221                 if !*self.available.lock().unwrap() {
 222                         return Err(());
 223                 }
 224                 Ok(EcdsaChannelSigner::sign_justice_revoked_htlc(&self.inner, justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
 225         }
 226
 227         fn sign_holder_htlc_transaction(
 228                 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
 229                 secp_ctx: &Secp256k1<secp256k1::All>
 230         ) -> Result<Signature, ()> {
 231                 if !*self.available.lock().unwrap() {
 232                         return Err(());
 233                 }
 234                 let state = self.state.lock().unwrap();
 235                 if state.last_holder_revoked_commitment - 1 != htlc_descriptor.per_commitment_number &&
 236                         state.last_holder_revoked_commitment - 2 != htlc_descriptor.per_commitment_number
 237                 {
 238                         if !self.disable_revocation_policy_check {
 239                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 240                                        state.last_holder_revoked_commitment, htlc_descriptor.per_commitment_number, self.inner.commitment_seed[0])
 241                         }
 242                 }
 243                 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
 244                 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(secp_ctx));
 245                 {
 246                         let witness_script = htlc_descriptor.witness_script(secp_ctx);
 247                         let sighash_type = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
 248                                 EcdsaSighashType::SinglePlusAnyoneCanPay
 249                         } else {
 250                                 EcdsaSighashType::All
 251                         };
 252                         let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
 253                                 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, sighash_type
 254                         ).unwrap();
 255                         let countersignatory_htlc_key = HtlcKey::from_basepoint(
 256                                 &secp_ctx, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint, &htlc_descriptor.per_commitment_point,
 257                         );
 258
 259                         secp_ctx.verify_ecdsa(
 260                                 &hash_to_message!(sighash.as_byte_array()), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key.to_public_key()
 261                         ).unwrap();
 262                 }
 263                 Ok(EcdsaChannelSigner::sign_holder_htlc_transaction(&self.inner, htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
 264         }
 265
 266         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, ()> {
 267                 if !*self.available.lock().unwrap() {
 268                         return Err(());
 269                 }
 270                 Ok(EcdsaChannelSigner::sign_counterparty_htlc_transaction(&self.inner, htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
 271         }
 272
 273         fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 274                 closing_tx.verify(self.inner.funding_outpoint().unwrap().into_bitcoin_outpoint())
 275                         .expect("derived different closing transaction");
 276                 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
 277         }
 278
 279         fn sign_holder_anchor_input(
 280                 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
 281         ) -> Result<Signature, ()> {
 282                 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
 283                 // As long as our minimum dust limit is enforced and is greater than our anchor output
 284                 // value, an anchor output can only have an index within [0, 1].
 285                 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
 286                 if !*self.available.lock().unwrap() {
 287                         return Err(());
 288                 }
 289                 EcdsaChannelSigner::sign_holder_anchor_input(&self.inner, anchor_tx, input, secp_ctx)
 290         }
 291
 292         fn sign_channel_announcement_with_funding_key(
 293                 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
 294         ) -> Result<Signature, ()> {
 295                 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
 296         }
 297 }
 298
 299 impl WriteableEcdsaChannelSigner for TestChannelSigner {}
 300
 301 #[cfg(taproot)]
 302 impl TaprootChannelSigner for TestChannelSigner {
 303         fn generate_local_nonce_pair(&self, commitment_number: u64, secp_ctx: &Secp256k1<All>) -> PublicNonce {
 304                 todo!()
 305         }
 306
 307         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>), ()> {
 308                 todo!()
 309         }
 310
 311         fn finalize_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, counterparty_partial_signature: PartialSignatureWithNonce, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
 312                 todo!()
 313         }
 314
 315         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, ()> {
 316                 todo!()
 317         }
 318
 319         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, ()> {
 320                 todo!()
 321         }
 322
 323         fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
 324                 todo!()
 325         }
 326
 327         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, ()> {
 328                 todo!()
 329         }
 330
 331         fn partially_sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
 332                 todo!()
 333         }
 334
 335         fn sign_holder_anchor_input(&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
 336                 todo!()
 337         }
 338 }
 339
 340 impl Writeable for TestChannelSigner {
 341         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 342                 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
 343                 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
 344                 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
 345                 // and will be serialized as needed by the implementation of that trait.
 346                 self.inner.write(writer)?;
 347                 Ok(())
 348         }
 349 }
 350
 351 impl TestChannelSigner {
 352         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 353                 commitment_tx.verify(
 354                         &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
 355                         self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
 356                 ).expect("derived different per-tx keys or built transaction")
 357         }
 358
 359         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 360                 commitment_tx.verify(
 361                         &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
 362                         self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
 363                 ).expect("derived different per-tx keys or built transaction")
 364         }
 365 }
 366
 367 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
 368 ///
 369 /// This structure is maintained by KeysInterface since we may have multiple copies of
 370 /// the signer and they must coordinate their state.
 371 #[derive(Clone)]
 372 pub struct EnforcementState {
 373         /// The last counterparty commitment number we signed, backwards counting
 374         pub last_counterparty_commitment: u64,
 375         /// The last counterparty commitment they revoked, backwards counting
 376         pub last_counterparty_revoked_commitment: u64,
 377         /// The last holder commitment number we revoked, backwards counting
 378         pub last_holder_revoked_commitment: u64,
 379         /// The last validated holder commitment number, backwards counting
 380         pub last_holder_commitment: u64,
 381 }
 382
 383 impl EnforcementState {
 384         /// Enforcement state for a new channel
 385         pub fn new() -> Self {
 386                 EnforcementState {
 387                         last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 388                         last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 389                         last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 390                         last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 391                 }
 392         }
 393 }