_ 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  49 /// - When signing, the holder transaction has not been revoked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         #[cfg(test)]
 121         pub fn set_available(&self, available: bool) {
 122                 *self.available.lock().unwrap() = available;
 123         }
 124 }
 125
 126 impl ChannelSigner for TestChannelSigner {
 127         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
 128                 self.inner.get_per_commitment_point(idx, secp_ctx)
 129         }
 130
 131         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
 132                 {
 133                         let mut state = self.state.lock().unwrap();
 134                         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);
 135                         assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
 136                         state.last_holder_revoked_commitment = idx;
 137                 }
 138                 self.inner.release_commitment_secret(idx)
 139         }
 140
 141         fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
 142                 let mut state = self.state.lock().unwrap();
 143                 let idx = holder_tx.commitment_number();
 144                 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);
 145                 state.last_holder_commitment = idx;
 146                 Ok(())
 147         }
 148
 149         fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
 150                 if !*self.available.lock().unwrap() {
 151                         return Err(());
 152                 }
 153                 let mut state = self.state.lock().unwrap();
 154                 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);
 155                 state.last_counterparty_revoked_commitment = idx;
 156                 Ok(())
 157         }
 158
 159         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
 160
 161         fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
 162
 163         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
 164                 self.inner.provide_channel_parameters(channel_parameters)
 165         }
 166 }
 167
 168 impl EcdsaChannelSigner for TestChannelSigner {
 169         fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 170                 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
 171
 172                 {
 173                         if !*self.available.lock().unwrap() {
 174                                 return Err(());
 175                         }
 176                         let mut state = self.state.lock().unwrap();
 177                         let actual_commitment_number = commitment_tx.commitment_number();
 178                         let last_commitment_number = state.last_counterparty_commitment;
 179                         // These commitment numbers are backwards counting.  We expect either the same as the previously encountered,
 180                         // or the next one.
 181                         assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
 182                         // Ensure that the counterparty doesn't get more than two broadcastable commitments -
 183                         // the last and the one we are trying to sign
 184                         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);
 185                         state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
 186                 }
 187
 188                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, preimages, secp_ctx).unwrap())
 189         }
 190
 191         fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 192                 if !*self.available.lock().unwrap() {
 193                         return Err(());
 194                 }
 195                 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
 196                 let state = self.state.lock().unwrap();
 197                 let commitment_number = trusted_tx.commitment_number();
 198                 if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
 199                         if !self.disable_revocation_policy_check {
 200                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 201                                        state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
 202                         }
 203                 }
 204                 Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 205         }
 206
 207         #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
 208         fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 209                 Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 210         }
 211
 212         fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 213                 Ok(EcdsaChannelSigner::sign_justice_revoked_output(&self.inner, justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
 214         }
 215
 216         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, ()> {
 217                 Ok(EcdsaChannelSigner::sign_justice_revoked_htlc(&self.inner, justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
 218         }
 219
 220         fn sign_holder_htlc_transaction(
 221                 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
 222                 secp_ctx: &Secp256k1<secp256k1::All>
 223         ) -> Result<Signature, ()> {
 224                 let state = self.state.lock().unwrap();
 225                 if state.last_holder_revoked_commitment - 1 != htlc_descriptor.per_commitment_number &&
 226                         state.last_holder_revoked_commitment - 2 != htlc_descriptor.per_commitment_number
 227                 {
 228                         if !self.disable_revocation_policy_check {
 229                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 230                                        state.last_holder_revoked_commitment, htlc_descriptor.per_commitment_number, self.inner.commitment_seed[0])
 231                         }
 232                 }
 233                 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
 234                 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(secp_ctx));
 235                 {
 236                         let witness_script = htlc_descriptor.witness_script(secp_ctx);
 237                         let sighash_type = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
 238                                 EcdsaSighashType::SinglePlusAnyoneCanPay
 239                         } else {
 240                                 EcdsaSighashType::All
 241                         };
 242                         let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
 243                                 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, sighash_type
 244                         ).unwrap();
 245                         let countersignatory_htlc_key = HtlcKey::from_basepoint(
 246                                 &secp_ctx, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint, &htlc_descriptor.per_commitment_point,
 247                         );
 248
 249                         secp_ctx.verify_ecdsa(
 250                                 &hash_to_message!(sighash.as_byte_array()), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key.to_public_key()
 251                         ).unwrap();
 252                 }
 253                 Ok(EcdsaChannelSigner::sign_holder_htlc_transaction(&self.inner, htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
 254         }
 255
 256         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, ()> {
 257                 Ok(EcdsaChannelSigner::sign_counterparty_htlc_transaction(&self.inner, htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
 258         }
 259
 260         fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 261                 closing_tx.verify(self.inner.funding_outpoint().unwrap().into_bitcoin_outpoint())
 262                         .expect("derived different closing transaction");
 263                 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
 264         }
 265
 266         fn sign_holder_anchor_input(
 267                 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
 268         ) -> Result<Signature, ()> {
 269                 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
 270                 // As long as our minimum dust limit is enforced and is greater than our anchor output
 271                 // value, an anchor output can only have an index within [0, 1].
 272                 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
 273                 EcdsaChannelSigner::sign_holder_anchor_input(&self.inner, anchor_tx, input, secp_ctx)
 274         }
 275
 276         fn sign_channel_announcement_with_funding_key(
 277                 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
 278         ) -> Result<Signature, ()> {
 279                 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
 280         }
 281 }
 282
 283 impl WriteableEcdsaChannelSigner for TestChannelSigner {}
 284
 285 #[cfg(taproot)]
 286 impl TaprootChannelSigner for TestChannelSigner {
 287         fn generate_local_nonce_pair(&self, commitment_number: u64, secp_ctx: &Secp256k1<All>) -> PublicNonce {
 288                 todo!()
 289         }
 290
 291         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>), ()> {
 292                 todo!()
 293         }
 294
 295         fn finalize_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, counterparty_partial_signature: PartialSignatureWithNonce, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
 296                 todo!()
 297         }
 298
 299         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, ()> {
 300                 todo!()
 301         }
 302
 303         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, ()> {
 304                 todo!()
 305         }
 306
 307         fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
 308                 todo!()
 309         }
 310
 311         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, ()> {
 312                 todo!()
 313         }
 314
 315         fn partially_sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
 316                 todo!()
 317         }
 318
 319         fn sign_holder_anchor_input(&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>) -> Result<secp256k1::schnorr::Signature, ()> {
 320                 todo!()
 321         }
 322 }
 323
 324 impl Writeable for TestChannelSigner {
 325         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 326                 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
 327                 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
 328                 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
 329                 // and will be serialized as needed by the implementation of that trait.
 330                 self.inner.write(writer)?;
 331                 Ok(())
 332         }
 333 }
 334
 335 impl TestChannelSigner {
 336         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 337                 commitment_tx.verify(
 338                         &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
 339                         self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
 340                 ).expect("derived different per-tx keys or built transaction")
 341         }
 342
 343         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 344                 commitment_tx.verify(
 345                         &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
 346                         self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
 347                 ).expect("derived different per-tx keys or built transaction")
 348         }
 349 }
 350
 351 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
 352 ///
 353 /// This structure is maintained by KeysInterface since we may have multiple copies of
 354 /// the signer and they must coordinate their state.
 355 #[derive(Clone)]
 356 pub struct EnforcementState {
 357         /// The last counterparty commitment number we signed, backwards counting
 358         pub last_counterparty_commitment: u64,
 359         /// The last counterparty commitment they revoked, backwards counting
 360         pub last_counterparty_revoked_commitment: u64,
 361         /// The last holder commitment number we revoked, backwards counting
 362         pub last_holder_revoked_commitment: u64,
 363         /// The last validated holder commitment number, backwards counting
 364         pub last_holder_commitment: u64,
 365 }
 366
 367 impl EnforcementState {
 368         /// Enforcement state for a new channel
 369         pub fn new() -> Self {
 370                 EnforcementState {
 371                         last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 372                         last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 373                         last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 374                         last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 375                 }
 376         }
 377 }