_ Git - rust-lightning/blob - lightning/src/util/enforcing_trait_impls.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 ln::chan_utils::{HTLCOutputInCommitment, ChannelPublicKeys, HolderCommitmentTransaction, CommitmentTransaction, ChannelTransactionParameters, TrustedCommitmentTransaction};
  11 use ln::{msgs, chan_utils};
  12 use chain::keysinterface::{ChannelKeys, InMemoryChannelKeys};
  13
  14 use std::cmp;
  15 use std::sync::{Mutex, Arc};
  16
  17 use bitcoin::blockdata::transaction::{Transaction, SigHashType};
  18 use bitcoin::util::bip143;
  19
  20 use bitcoin::secp256k1;
  21 use bitcoin::secp256k1::key::{SecretKey, PublicKey};
  22 use bitcoin::secp256k1::{Secp256k1, Signature};
  23 use util::ser::{Writeable, Writer, Readable};
  24 use std::io::Error;
  25 use ln::msgs::DecodeError;
  26
  27 /// An implementation of ChannelKeys that enforces some policy checks.
  28 ///
  29 /// Eventually we will probably want to expose a variant of this which would essentially
  30 /// be what you'd want to run on a hardware wallet.
  31 #[derive(Clone)]
  32 pub struct EnforcingChannelKeys {
  33         pub inner: InMemoryChannelKeys,
  34         last_commitment_number: Arc<Mutex<Option<u64>>>,
  35 }
  36
  37 impl EnforcingChannelKeys {
  38         pub fn new(inner: InMemoryChannelKeys) -> Self {
  39                 Self {
  40                         inner,
  41                         last_commitment_number: Arc::new(Mutex::new(None)),
  42                 }
  43         }
  44 }
  45
  46 impl ChannelKeys for EnforcingChannelKeys {
  47         fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey {
  48                 self.inner.get_per_commitment_point(idx, secp_ctx)
  49         }
  50
  51         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
  52                 // TODO: enforce the ChannelKeys contract - error here if we already signed this commitment
  53                 self.inner.release_commitment_secret(idx)
  54         }
  55
  56         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
  57         fn key_derivation_params(&self) -> (u64, u64) { self.inner.key_derivation_params() }
  58
  59         fn sign_counterparty_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
  60                 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
  61
  62                 {
  63                         let mut last_commitment_number_guard = self.last_commitment_number.lock().unwrap();
  64                         let actual_commitment_number = commitment_tx.commitment_number();
  65                         let last_commitment_number = last_commitment_number_guard.unwrap_or(actual_commitment_number);
  66                         // These commitment numbers are backwards counting.  We expect either the same as the previously encountered,
  67                         // or the next one.
  68                         assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
  69                         *last_commitment_number_guard = Some(cmp::min(last_commitment_number, actual_commitment_number))
  70                 }
  71
  72                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, secp_ctx).unwrap())
  73         }
  74
  75         fn sign_holder_commitment_and_htlcs<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
  76                 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
  77                 let commitment_txid = trusted_tx.txid();
  78                 let holder_csv = self.inner.counterparty_selected_contest_delay();
  79
  80                 for (this_htlc, sig) in trusted_tx.htlcs().iter().zip(&commitment_tx.counterparty_htlc_sigs) {
  81                         assert!(this_htlc.transaction_output_index.is_some());
  82                         let keys = trusted_tx.keys();
  83                         let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, trusted_tx.feerate_per_kw(), holder_csv, &this_htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
  84
  85                         let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc, &keys);
  86
  87                         let sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, this_htlc.amount_msat / 1000, SigHashType::All)[..]);
  88                         secp_ctx.verify(&sighash, sig, &keys.countersignatory_htlc_key).unwrap();
  89                 }
  90
  91                 // TODO: enforce the ChannelKeys contract - error if this commitment was already revoked
  92                 // TODO: need the commitment number
  93                 Ok(self.inner.sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
  94         }
  95
  96         #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
  97         fn unsafe_sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
  98                 Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
  99         }
 100
 101         fn sign_justice_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option<HTLCOutputInCommitment>, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
 102                 Ok(self.inner.sign_justice_transaction(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
 103         }
 104
 105         fn sign_counterparty_htlc_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
 106                 Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
 107         }
 108
 109         fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
 110                 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
 111         }
 112
 113         fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
 114                 self.inner.sign_channel_announcement(msg, secp_ctx)
 115         }
 116
 117         fn ready_channel(&mut self, channel_parameters: &ChannelTransactionParameters) {
 118                 self.inner.ready_channel(channel_parameters)
 119         }
 120 }
 121
 122
 123 impl Writeable for EnforcingChannelKeys {
 124         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 125                 self.inner.write(writer)?;
 126                 let last = *self.last_commitment_number.lock().unwrap();
 127                 last.write(writer)?;
 128                 Ok(())
 129         }
 130 }
 131
 132 impl Readable for EnforcingChannelKeys {
 133         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 134                 let inner = Readable::read(reader)?;
 135                 let last_commitment_number = Readable::read(reader)?;
 136                 Ok(EnforcingChannelKeys {
 137                         inner,
 138                         last_commitment_number: Arc::new(Mutex::new(last_commitment_number))
 139                 })
 140         }
 141 }
 142
 143 impl EnforcingChannelKeys {
 144         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 145                 commitment_tx.verify(&self.inner.get_channel_parameters().as_counterparty_broadcastable(),
 146                                      self.inner.counterparty_pubkeys(), self.inner.pubkeys(), secp_ctx)
 147                         .expect("derived different per-tx keys or built transaction")
 148         }
 149
 150         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 151                 commitment_tx.verify(&self.inner.get_channel_parameters().as_holder_broadcastable(),
 152                                      self.inner.pubkeys(), self.inner.counterparty_pubkeys(), secp_ctx)
 153                         .expect("derived different per-tx keys or built transaction")
 154         }
 155 }