_ 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::{chan_utils, msgs};
  12 use chain::keysinterface::{Sign, InMemorySigner, BaseSign};
  13
  14 use core::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 /// Initial value for revoked commitment downward counter
  28 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
  29
  30 /// An implementation of Sign that enforces some policy checks.  The current checks
  31 /// are an incomplete set.  They include:
  32 ///
  33 /// - When signing, the holder transaction has not been revoked
  34 /// - When revoking, the holder transaction has not been signed
  35 /// - The holder commitment number is monotonic and without gaps
  36 /// - The counterparty commitment number is monotonic and without gaps
  37 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
  38 ///
  39 /// Eventually we will probably want to expose a variant of this which would essentially
  40 /// be what you'd want to run on a hardware wallet.
  41 #[derive(Clone)]
  42 pub struct EnforcingSigner {
  43         pub inner: InMemorySigner,
  44         /// The last counterparty commitment number we signed, backwards counting
  45         pub last_commitment_number: Arc<Mutex<Option<u64>>>,
  46         /// The last holder commitment number we revoked, backwards counting
  47         pub revoked_commitment: Arc<Mutex<u64>>,
  48         pub disable_revocation_policy_check: bool,
  49 }
  50
  51 impl EnforcingSigner {
  52         /// Construct an EnforcingSigner
  53         pub fn new(inner: InMemorySigner) -> Self {
  54                 Self {
  55                         inner,
  56                         last_commitment_number: Arc::new(Mutex::new(None)),
  57                         revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)),
  58                         disable_revocation_policy_check: false
  59                 }
  60         }
  61
  62         /// Construct an EnforcingSigner with externally managed storage
  63         ///
  64         /// Since there are multiple copies of this struct for each channel, some coordination is needed
  65         /// so that all copies are aware of revocations.  A pointer to this state is provided here, usually
  66         /// by an implementation of KeysInterface.
  67         pub fn new_with_revoked(inner: InMemorySigner, revoked_commitment: Arc<Mutex<u64>>, disable_revocation_policy_check: bool) -> Self {
  68                 Self {
  69                         inner,
  70                         last_commitment_number: Arc::new(Mutex::new(None)),
  71                         revoked_commitment,
  72                         disable_revocation_policy_check
  73                 }
  74         }
  75 }
  76
  77 impl BaseSign for EnforcingSigner {
  78         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
  79                 self.inner.get_per_commitment_point(idx, secp_ctx)
  80         }
  81
  82         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
  83                 {
  84                         let mut revoked = self.revoked_commitment.lock().unwrap();
  85                         assert!(idx == *revoked || idx == *revoked - 1, "can only revoke the current or next unrevoked commitment - trying {}, revoked {}", idx, *revoked);
  86                         *revoked = idx;
  87                 }
  88                 self.inner.release_commitment_secret(idx)
  89         }
  90
  91         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
  92         fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
  93
  94         fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
  95                 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
  96
  97                 {
  98                         let mut last_commitment_number_guard = self.last_commitment_number.lock().unwrap();
  99                         let actual_commitment_number = commitment_tx.commitment_number();
 100                         let last_commitment_number = last_commitment_number_guard.unwrap_or(actual_commitment_number);
 101                         // These commitment numbers are backwards counting.  We expect either the same as the previously encountered,
 102                         // or the next one.
 103                         assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
 104                         *last_commitment_number_guard = Some(cmp::min(last_commitment_number, actual_commitment_number))
 105                 }
 106
 107                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, secp_ctx).unwrap())
 108         }
 109
 110         fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 111                 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
 112                 let commitment_txid = trusted_tx.txid();
 113                 let holder_csv = self.inner.counterparty_selected_contest_delay();
 114
 115                 let revoked = self.revoked_commitment.lock().unwrap();
 116                 let commitment_number = trusted_tx.commitment_number();
 117                 if *revoked - 1 != commitment_number && *revoked - 2 != commitment_number {
 118                         if !self.disable_revocation_policy_check {
 119                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 120                                        *revoked, commitment_number, self.inner.commitment_seed[0])
 121                         }
 122                 }
 123
 124                 for (this_htlc, sig) in trusted_tx.htlcs().iter().zip(&commitment_tx.counterparty_htlc_sigs) {
 125                         assert!(this_htlc.transaction_output_index.is_some());
 126                         let keys = trusted_tx.keys();
 127                         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);
 128
 129                         let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc, &keys);
 130
 131                         let sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, this_htlc.amount_msat / 1000, SigHashType::All)[..]);
 132                         secp_ctx.verify(&sighash, sig, &keys.countersignatory_htlc_key).unwrap();
 133                 }
 134
 135                 Ok(self.inner.sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
 136         }
 137
 138         #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
 139         fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 140                 Ok(self.inner.unsafe_sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
 141         }
 142
 143         fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 144                 Ok(self.inner.sign_justice_revoked_output(justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
 145         }
 146
 147         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, ()> {
 148                 Ok(self.inner.sign_justice_revoked_htlc(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
 149         }
 150
 151         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, ()> {
 152                 Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
 153         }
 154
 155         fn sign_closing_transaction(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 156                 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
 157         }
 158
 159         fn sign_channel_announcement(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 160                 self.inner.sign_channel_announcement(msg, secp_ctx)
 161         }
 162
 163         fn ready_channel(&mut self, channel_parameters: &ChannelTransactionParameters) {
 164                 self.inner.ready_channel(channel_parameters)
 165         }
 166 }
 167
 168 impl Sign for EnforcingSigner {}
 169
 170 impl Writeable for EnforcingSigner {
 171         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 172                 self.inner.write(writer)?;
 173                 let last = *self.last_commitment_number.lock().unwrap();
 174                 last.write(writer)?;
 175                 Ok(())
 176         }
 177 }
 178
 179 impl Readable for EnforcingSigner {
 180         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 181                 let inner = Readable::read(reader)?;
 182                 let last_commitment_number = Readable::read(reader)?;
 183                 Ok(EnforcingSigner {
 184                         inner,
 185                         last_commitment_number: Arc::new(Mutex::new(last_commitment_number)),
 186                         revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)),
 187                         disable_revocation_policy_check: false,
 188                 })
 189         }
 190 }
 191
 192 impl EnforcingSigner {
 193         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 194                 commitment_tx.verify(&self.inner.get_channel_parameters().as_counterparty_broadcastable(),
 195                                      self.inner.counterparty_pubkeys(), self.inner.pubkeys(), secp_ctx)
 196                         .expect("derived different per-tx keys or built transaction")
 197         }
 198
 199         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 200                 commitment_tx.verify(&self.inner.get_channel_parameters().as_holder_broadcastable(),
 201                                      self.inner.pubkeys(), self.inner.counterparty_pubkeys(), secp_ctx)
 202                         .expect("derived different per-tx keys or built transaction")
 203         }
 204 }