_ 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::{chan_utils, msgs, PaymentPreimage};
  13 use crate::sign::{WriteableEcdsaChannelSigner, InMemorySigner, ChannelSigner, EcdsaChannelSigner};
  14
  15 use crate::prelude::*;
  16 use core::cmp;
  17 use crate::sync::{Mutex, Arc};
  18 #[cfg(test)] use crate::sync::MutexGuard;
  19
  20 use bitcoin::blockdata::transaction::Transaction;
  21 use bitcoin::hashes::Hash;
  22 use bitcoin::sighash;
  23 use bitcoin::sighash::EcdsaSighashType;
  24
  25 use bitcoin::secp256k1;
  26 use bitcoin::secp256k1::{SecretKey, PublicKey};
  27 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
  28 use crate::sign::HTLCDescriptor;
  29 use crate::util::ser::{Writeable, Writer};
  30 use crate::io::Error;
  31 use crate::ln::features::ChannelTypeFeatures;
  32
  33 /// Initial value for revoked commitment downward counter
  34 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
  35
  36 /// An implementation of Sign that enforces some policy checks.  The current checks
  37 /// are an incomplete set.  They include:
  38 ///
  39 /// - When signing, the holder transaction has not been revoked
  40 /// - When revoking, the holder transaction has not been signed
  41 /// - The holder commitment number is monotonic and without gaps
  42 /// - The revoked holder commitment number is monotonic and without gaps
  43 /// - There is at least one unrevoked holder transaction at all times
  44 /// - The counterparty commitment number is monotonic and without gaps
  45 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
  46 ///
  47 /// Eventually we will probably want to expose a variant of this which would essentially
  48 /// be what you'd want to run on a hardware wallet.
  49 ///
  50 /// Note that counterparty signatures on the holder transaction are not checked, but it should
  51 /// be in a complete implementation.
  52 ///
  53 /// Note that before we do so we should ensure its serialization format has backwards- and
  54 /// forwards-compatibility prefix/suffixes!
  55 #[derive(Clone)]
  56 pub struct TestChannelSigner {
  57         pub inner: InMemorySigner,
  58         /// Channel state used for policy enforcement
  59         pub state: Arc<Mutex<EnforcementState>>,
  60         pub disable_revocation_policy_check: bool,
  61         /// When `true` (the default), the signer will respond immediately with signatures. When `false`,
  62         /// the signer will return an error indicating that it is unavailable.
  63         pub available: Arc<Mutex<bool>>,
  64 }
  65
  66 impl PartialEq for TestChannelSigner {
  67         fn eq(&self, o: &Self) -> bool {
  68                 Arc::ptr_eq(&self.state, &o.state)
  69         }
  70 }
  71
  72 impl TestChannelSigner {
  73         /// Construct an TestChannelSigner
  74         pub fn new(inner: InMemorySigner) -> Self {
  75                 let state = Arc::new(Mutex::new(EnforcementState::new()));
  76                 Self {
  77                         inner,
  78                         state,
  79                         disable_revocation_policy_check: false,
  80                         available: Arc::new(Mutex::new(true)),
  81                 }
  82         }
  83
  84         /// Construct an TestChannelSigner with externally managed storage
  85         ///
  86         /// Since there are multiple copies of this struct for each channel, some coordination is needed
  87         /// so that all copies are aware of enforcement state.  A pointer to this state is provided
  88         /// here, usually by an implementation of KeysInterface.
  89         pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
  90                 Self {
  91                         inner,
  92                         state,
  93                         disable_revocation_policy_check,
  94                         available: Arc::new(Mutex::new(true)),
  95                 }
  96         }
  97
  98         pub fn channel_type_features(&self) -> &ChannelTypeFeatures { self.inner.channel_type_features().unwrap() }
  99
 100         #[cfg(test)]
 101         pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
 102                 self.state.lock().unwrap()
 103         }
 104
 105         /// Marks the signer's availability.
 106         ///
 107         /// When `true`, methods are forwarded to the underlying signer as normal. When `false`, some
 108         /// methods will return `Err` indicating that the signer is unavailable. Intended to be used for
 109         /// testing asynchronous signing.
 110         #[cfg(test)]
 111         pub fn set_available(&self, available: bool) {
 112                 *self.available.lock().unwrap() = available;
 113         }
 114 }
 115
 116 impl ChannelSigner for TestChannelSigner {
 117         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
 118                 self.inner.get_per_commitment_point(idx, secp_ctx)
 119         }
 120
 121         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
 122                 {
 123                         let mut state = self.state.lock().unwrap();
 124                         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);
 125                         assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
 126                         state.last_holder_revoked_commitment = idx;
 127                 }
 128                 self.inner.release_commitment_secret(idx)
 129         }
 130
 131         fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
 132                 let mut state = self.state.lock().unwrap();
 133                 let idx = holder_tx.commitment_number();
 134                 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);
 135                 state.last_holder_commitment = idx;
 136                 Ok(())
 137         }
 138
 139         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
 140
 141         fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
 142
 143         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
 144                 self.inner.provide_channel_parameters(channel_parameters)
 145         }
 146 }
 147
 148 impl EcdsaChannelSigner for TestChannelSigner {
 149         fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 150                 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
 151
 152                 {
 153                         if !*self.available.lock().unwrap() {
 154                                 return Err(());
 155                         }
 156                         let mut state = self.state.lock().unwrap();
 157                         let actual_commitment_number = commitment_tx.commitment_number();
 158                         let last_commitment_number = state.last_counterparty_commitment;
 159                         // These commitment numbers are backwards counting.  We expect either the same as the previously encountered,
 160                         // or the next one.
 161                         assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
 162                         // Ensure that the counterparty doesn't get more than two broadcastable commitments -
 163                         // the last and the one we are trying to sign
 164                         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);
 165                         state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
 166                 }
 167
 168                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, preimages, secp_ctx).unwrap())
 169         }
 170
 171         fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
 172                 if !*self.available.lock().unwrap() {
 173                         return Err(());
 174                 }
 175                 let mut state = self.state.lock().unwrap();
 176                 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);
 177                 state.last_counterparty_revoked_commitment = idx;
 178                 Ok(())
 179         }
 180
 181         fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 182                 if !*self.available.lock().unwrap() {
 183                         return Err(());
 184                 }
 185                 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
 186                 let state = self.state.lock().unwrap();
 187                 let commitment_number = trusted_tx.commitment_number();
 188                 if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
 189                         if !self.disable_revocation_policy_check {
 190                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 191                                        state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
 192                         }
 193                 }
 194                 Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 195         }
 196
 197         #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
 198         fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 199                 Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 200         }
 201
 202         fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 203                 Ok(self.inner.sign_justice_revoked_output(justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
 204         }
 205
 206         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, ()> {
 207                 Ok(self.inner.sign_justice_revoked_htlc(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
 208         }
 209
 210         fn sign_holder_htlc_transaction(
 211                 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
 212                 secp_ctx: &Secp256k1<secp256k1::All>
 213         ) -> Result<Signature, ()> {
 214                 let state = self.state.lock().unwrap();
 215                 if state.last_holder_revoked_commitment - 1 != htlc_descriptor.per_commitment_number &&
 216                         state.last_holder_revoked_commitment - 2 != htlc_descriptor.per_commitment_number
 217                 {
 218                         if !self.disable_revocation_policy_check {
 219                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 220                                        state.last_holder_revoked_commitment, htlc_descriptor.per_commitment_number, self.inner.commitment_seed[0])
 221                         }
 222                 }
 223                 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
 224                 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(secp_ctx));
 225                 {
 226                         let witness_script = htlc_descriptor.witness_script(secp_ctx);
 227                         let sighash_type = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
 228                                 EcdsaSighashType::SinglePlusAnyoneCanPay
 229                         } else {
 230                                 EcdsaSighashType::All
 231                         };
 232                         let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
 233                                 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, sighash_type
 234                         ).unwrap();
 235                         let countersignatory_htlc_key = chan_utils::derive_public_key(
 236                                 &secp_ctx, &htlc_descriptor.per_commitment_point, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint
 237                         );
 238                         secp_ctx.verify_ecdsa(
 239                                 &hash_to_message!(sighash.as_byte_array()), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key
 240                         ).unwrap();
 241                 }
 242                 Ok(self.inner.sign_holder_htlc_transaction(htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
 243         }
 244
 245         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, ()> {
 246                 Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
 247         }
 248
 249         fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 250                 closing_tx.verify(self.inner.funding_outpoint().unwrap().into_bitcoin_outpoint())
 251                         .expect("derived different closing transaction");
 252                 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
 253         }
 254
 255         fn sign_holder_anchor_input(
 256                 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
 257         ) -> Result<Signature, ()> {
 258                 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
 259                 // As long as our minimum dust limit is enforced and is greater than our anchor output
 260                 // value, an anchor output can only have an index within [0, 1].
 261                 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
 262                 self.inner.sign_holder_anchor_input(anchor_tx, input, secp_ctx)
 263         }
 264
 265         fn sign_channel_announcement_with_funding_key(
 266                 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
 267         ) -> Result<Signature, ()> {
 268                 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
 269         }
 270 }
 271
 272 impl WriteableEcdsaChannelSigner for TestChannelSigner {}
 273
 274 impl Writeable for TestChannelSigner {
 275         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 276                 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
 277                 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
 278                 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
 279                 // and will be serialized as needed by the implementation of that trait.
 280                 self.inner.write(writer)?;
 281                 Ok(())
 282         }
 283 }
 284
 285 impl TestChannelSigner {
 286         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 287                 commitment_tx.verify(
 288                         &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
 289                         self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
 290                 ).expect("derived different per-tx keys or built transaction")
 291         }
 292
 293         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 294                 commitment_tx.verify(
 295                         &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
 296                         self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
 297                 ).expect("derived different per-tx keys or built transaction")
 298         }
 299 }
 300
 301 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
 302 ///
 303 /// This structure is maintained by KeysInterface since we may have multiple copies of
 304 /// the signer and they must coordinate their state.
 305 #[derive(Clone)]
 306 pub struct EnforcementState {
 307         /// The last counterparty commitment number we signed, backwards counting
 308         pub last_counterparty_commitment: u64,
 309         /// The last counterparty commitment they revoked, backwards counting
 310         pub last_counterparty_revoked_commitment: u64,
 311         /// The last holder commitment number we revoked, backwards counting
 312         pub last_holder_revoked_commitment: u64,
 313         /// The last validated holder commitment number, backwards counting
 314         pub last_holder_commitment: u64,
 315 }
 316
 317 impl EnforcementState {
 318         /// Enforcement state for a new channel
 319         pub fn new() -> Self {
 320                 EnforcementState {
 321                         last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 322                         last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 323                         last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 324                         last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 325                 }
 326         }
 327 }