_ 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;
  14 use crate::ln::types::PaymentPreimage;
  15 use crate::sign::{InMemorySigner, ChannelSigner};
  16 use crate::sign::ecdsa::{EcdsaChannelSigner, WriteableEcdsaChannelSigner};
  17
  18 #[allow(unused_imports)]
  19 use crate::prelude::*;
  20
  21 use core::cmp;
  22 use crate::sync::{Mutex, Arc};
  23 #[cfg(test)] use crate::sync::MutexGuard;
  24
  25 use bitcoin::blockdata::transaction::Transaction;
  26 use bitcoin::hashes::Hash;
  27 use bitcoin::sighash;
  28 use bitcoin::sighash::EcdsaSighashType;
  29
  30 use bitcoin::secp256k1;
  31 #[cfg(taproot)]
  32 use bitcoin::secp256k1::All;
  33 use bitcoin::secp256k1::{SecretKey, PublicKey};
  34 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
  35 #[cfg(taproot)]
  36 use musig2::types::{PartialSignature, PublicNonce, SecretNonce};
  37 use crate::sign::HTLCDescriptor;
  38 use crate::util::ser::{Writeable, Writer};
  39 use crate::io::Error;
  40 use crate::ln::features::ChannelTypeFeatures;
  41 #[cfg(taproot)]
  42 use crate::ln::msgs::PartialSignatureWithNonce;
  43 #[cfg(taproot)]
  44 use crate::sign::taproot::TaprootChannelSigner;
  45
  46 /// Initial value for revoked commitment downward counter
  47 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
  48
  49 /// An implementation of Sign that enforces some policy checks.  The current checks
  50 /// are an incomplete set.  They include:
  51 ///
  52 /// - When signing, the holder transaction has not been revoked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
  59 ///
  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.
  62 ///
  63 /// Note that counterparty signatures on the holder transaction are not checked, but it should
  64 /// be in a complete implementation.
  65 ///
  66 /// Note that before we do so we should ensure its serialization format has backwards- and
  67 /// forwards-compatibility prefix/suffixes!
  68 #[derive(Clone)]
  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>>,
  77 }
  78
  79 impl PartialEq for TestChannelSigner {
  80         fn eq(&self, o: &Self) -> bool {
  81                 Arc::ptr_eq(&self.state, &o.state)
  82         }
  83 }
  84
  85 impl TestChannelSigner {
  86         /// Construct an TestChannelSigner
  87         pub fn new(inner: InMemorySigner) -> Self {
  88                 let state = Arc::new(Mutex::new(EnforcementState::new()));
  89                 Self {
  90                         inner,
  91                         state,
  92                         disable_revocation_policy_check: false,
  93                         available: Arc::new(Mutex::new(true)),
  94                 }
  95         }
  96
  97         /// Construct an TestChannelSigner with externally managed storage
  98         ///
  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 {
 103                 Self {
 104                         inner,
 105                         state,
 106                         disable_revocation_policy_check,
 107                         available: Arc::new(Mutex::new(true)),
 108                 }
 109         }
 110
 111         pub fn channel_type_features(&self) -> &ChannelTypeFeatures { self.inner.channel_type_features().unwrap() }
 112
 113         #[cfg(test)]
 114         pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
 115                 self.state.lock().unwrap()
 116         }
 117
 118         /// Marks the signer's availability.
 119         ///
 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;
 125         }
 126 }
 127
 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)
 131         }
 132
 133         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
 134                 {
 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;
 139                 }
 140                 self.inner.release_commitment_secret(idx)
 141         }
 142
 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;
 148                 Ok(())
 149         }
 150
 151         fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
 152                 if !*self.available.lock().unwrap() {
 153                         return Err(());
 154                 }
 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;
 158                 Ok(())
 159         }
 160
 161         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
 162
 163         fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
 164
 165         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
 166                 self.inner.provide_channel_parameters(channel_parameters)
 167         }
 168 }
 169
 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);
 173
 174                 {
 175                         if !*self.available.lock().unwrap() {
 176                                 return Err(());
 177                         }
 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,
 182                         // or the next one.
 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)
 188                 }
 189
 190                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, inbound_htlc_preimages, outbound_htlc_preimages, secp_ctx).unwrap())
 191         }
 192
 193         fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 194                 if !*self.available.lock().unwrap() {
 195                         return Err(());
 196                 }
 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])
 204                         }
 205                 }
 206                 Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 207         }
 208
 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())
 212         }
 213
 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() {
 216                         return Err(());
 217                 }
 218                 Ok(EcdsaChannelSigner::sign_justice_revoked_output(&self.inner, justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
 219         }
 220
 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() {
 223                         return Err(());
 224                 }
 225                 Ok(EcdsaChannelSigner::sign_justice_revoked_htlc(&self.inner, justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
 226         }
 227
 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() {
 233                         return Err(());
 234                 }
 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
 238                 {
 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])
 242                         }
 243                 }
 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));
 246                 {
 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
 250                         } else {
 251                                 EcdsaSighashType::All
 252                         };
 253                         let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
 254                                 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, sighash_type
 255                         ).unwrap();
 256                         let countersignatory_htlc_key = HtlcKey::from_basepoint(
 257                                 &secp_ctx, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint, &htlc_descriptor.per_commitment_point,
 258                         );
 259
 260                         secp_ctx.verify_ecdsa(
 261                                 &hash_to_message!(sighash.as_byte_array()), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key.to_public_key()
 262                         ).unwrap();
 263                 }
 264                 Ok(EcdsaChannelSigner::sign_holder_htlc_transaction(&self.inner, htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
 265         }
 266
 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() {
 269                         return Err(());
 270                 }
 271                 Ok(EcdsaChannelSigner::sign_counterparty_htlc_transaction(&self.inner, htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
 272         }
 273
 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())
 278         }
 279
 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() {
 288                         return Err(());
 289                 }
 290                 EcdsaChannelSigner::sign_holder_anchor_input(&self.inner, anchor_tx, input, secp_ctx)
 291         }
 292
 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)
 297         }
 298 }
 299
 300 impl WriteableEcdsaChannelSigner for TestChannelSigner {}
 301
 302 #[cfg(taproot)]
 303 impl TaprootChannelSigner for TestChannelSigner {
 304         fn generate_local_nonce_pair(&self, commitment_number: u64, secp_ctx: &Secp256k1<All>) -> PublicNonce {
 305                 todo!()
 306         }
 307
 308         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>), ()> {
 309                 todo!()
 310         }
 311
 312         fn finalize_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, counterparty_partial_signature: PartialSignatureWithNonce, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
 313                 todo!()
 314         }
 315
 316         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, ()> {
 317                 todo!()
 318         }
 319
 320         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, ()> {
 321                 todo!()
 322         }
 323
 324         fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
 325                 todo!()
 326         }
 327
 328         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, ()> {
 329                 todo!()
 330         }
 331
 332         fn partially_sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
 333                 todo!()
 334         }
 335
 336         fn sign_holder_anchor_input(&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
 337                 todo!()
 338         }
 339 }
 340
 341 impl Writeable for TestChannelSigner {
 342         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 343                 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
 344                 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
 345                 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
 346                 // and will be serialized as needed by the implementation of that trait.
 347                 self.inner.write(writer)?;
 348                 Ok(())
 349         }
 350 }
 351
 352 impl TestChannelSigner {
 353         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 354                 commitment_tx.verify(
 355                         &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
 356                         self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
 357                 ).expect("derived different per-tx keys or built transaction")
 358         }
 359
 360         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 361                 commitment_tx.verify(
 362                         &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
 363                         self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
 364                 ).expect("derived different per-tx keys or built transaction")
 365         }
 366 }
 367
 368 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
 369 ///
 370 /// This structure is maintained by KeysInterface since we may have multiple copies of
 371 /// the signer and they must coordinate their state.
 372 #[derive(Clone)]
 373 pub struct EnforcementState {
 374         /// The last counterparty commitment number we signed, backwards counting
 375         pub last_counterparty_commitment: u64,
 376         /// The last counterparty commitment they revoked, backwards counting
 377         pub last_counterparty_revoked_commitment: u64,
 378         /// The last holder commitment number we revoked, backwards counting
 379         pub last_holder_revoked_commitment: u64,
 380         /// The last validated holder commitment number, backwards counting
 381         pub last_holder_commitment: u64,
 382 }
 383
 384 impl EnforcementState {
 385         /// Enforcement state for a new channel
 386         pub fn new() -> Self {
 387                 EnforcementState {
 388                         last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 389                         last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 390                         last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 391                         last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 392                 }
 393         }
 394 }