_ 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 io;
  15 use prelude::*;
  16 use core::cmp;
  17 use sync::{Mutex, Arc};
  18
  19 use bitcoin::blockdata::transaction::{Transaction, SigHashType};
  20 use bitcoin::util::bip143;
  21
  22 use bitcoin::secp256k1;
  23 use bitcoin::secp256k1::key::{SecretKey, PublicKey};
  24 use bitcoin::secp256k1::{Secp256k1, Signature};
  25 use util::ser::{Writeable, Writer, Readable};
  26 use io::Error;
  27 use ln::msgs::DecodeError;
  28
  29 /// Initial value for revoked commitment downward counter
  30 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
  31
  32 /// An implementation of Sign that enforces some policy checks.  The current checks
  33 /// are an incomplete set.  They include:
  34 ///
  35 /// - When signing, the holder transaction has not been revoked
  36 /// - When revoking, the holder transaction has not been signed
  37 /// - The holder commitment number is monotonic and without gaps
  38 /// - The counterparty commitment number is monotonic and without gaps
  39 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
  40 ///
  41 /// Eventually we will probably want to expose a variant of this which would essentially
  42 /// be what you'd want to run on a hardware wallet.
  43 ///
  44 /// Note that before we do so we should ensure its serialization format has backwards- and
  45 /// forwards-compatibility prefix/suffixes!
  46 #[derive(Clone)]
  47 pub struct EnforcingSigner {
  48         pub inner: InMemorySigner,
  49         /// The last counterparty commitment number we signed, backwards counting
  50         pub last_commitment_number: Arc<Mutex<Option<u64>>>,
  51         /// The last holder commitment number we revoked, backwards counting
  52         pub revoked_commitment: Arc<Mutex<u64>>,
  53         pub disable_revocation_policy_check: bool,
  54 }
  55
  56 impl EnforcingSigner {
  57         /// Construct an EnforcingSigner
  58         pub fn new(inner: InMemorySigner) -> Self {
  59                 Self {
  60                         inner,
  61                         last_commitment_number: Arc::new(Mutex::new(None)),
  62                         revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)),
  63                         disable_revocation_policy_check: false
  64                 }
  65         }
  66
  67         /// Construct an EnforcingSigner with externally managed storage
  68         ///
  69         /// Since there are multiple copies of this struct for each channel, some coordination is needed
  70         /// so that all copies are aware of revocations.  A pointer to this state is provided here, usually
  71         /// by an implementation of KeysInterface.
  72         pub fn new_with_revoked(inner: InMemorySigner, revoked_commitment: Arc<Mutex<u64>>, disable_revocation_policy_check: bool) -> Self {
  73                 Self {
  74                         inner,
  75                         last_commitment_number: Arc::new(Mutex::new(None)),
  76                         revoked_commitment,
  77                         disable_revocation_policy_check
  78                 }
  79         }
  80 }
  81
  82 impl BaseSign for EnforcingSigner {
  83         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
  84                 self.inner.get_per_commitment_point(idx, secp_ctx)
  85         }
  86
  87         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
  88                 {
  89                         let mut revoked = self.revoked_commitment.lock().unwrap();
  90                         assert!(idx == *revoked || idx == *revoked - 1, "can only revoke the current or next unrevoked commitment - trying {}, revoked {}", idx, *revoked);
  91                         *revoked = idx;
  92                 }
  93                 self.inner.release_commitment_secret(idx)
  94         }
  95
  96         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
  97         fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
  98
  99         fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 100                 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
 101
 102                 {
 103                         let mut last_commitment_number_guard = self.last_commitment_number.lock().unwrap();
 104                         let actual_commitment_number = commitment_tx.commitment_number();
 105                         let last_commitment_number = last_commitment_number_guard.unwrap_or(actual_commitment_number);
 106                         // These commitment numbers are backwards counting.  We expect either the same as the previously encountered,
 107                         // or the next one.
 108                         assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
 109                         *last_commitment_number_guard = Some(cmp::min(last_commitment_number, actual_commitment_number))
 110                 }
 111
 112                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, secp_ctx).unwrap())
 113         }
 114
 115         fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 116                 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
 117                 let commitment_txid = trusted_tx.txid();
 118                 let holder_csv = self.inner.counterparty_selected_contest_delay();
 119
 120                 let revoked = self.revoked_commitment.lock().unwrap();
 121                 let commitment_number = trusted_tx.commitment_number();
 122                 if *revoked - 1 != commitment_number && *revoked - 2 != commitment_number {
 123                         if !self.disable_revocation_policy_check {
 124                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 125                                        *revoked, commitment_number, self.inner.commitment_seed[0])
 126                         }
 127                 }
 128
 129                 for (this_htlc, sig) in trusted_tx.htlcs().iter().zip(&commitment_tx.counterparty_htlc_sigs) {
 130                         assert!(this_htlc.transaction_output_index.is_some());
 131                         let keys = trusted_tx.keys();
 132                         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);
 133
 134                         let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc, &keys);
 135
 136                         let sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, this_htlc.amount_msat / 1000, SigHashType::All)[..]);
 137                         secp_ctx.verify(&sighash, sig, &keys.countersignatory_htlc_key).unwrap();
 138                 }
 139
 140                 Ok(self.inner.sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
 141         }
 142
 143         #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
 144         fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 145                 Ok(self.inner.unsafe_sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
 146         }
 147
 148         fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 149                 Ok(self.inner.sign_justice_revoked_output(justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
 150         }
 151
 152         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, ()> {
 153                 Ok(self.inner.sign_justice_revoked_htlc(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
 154         }
 155
 156         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, ()> {
 157                 Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
 158         }
 159
 160         fn sign_closing_transaction(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 161                 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
 162         }
 163
 164         fn sign_channel_announcement(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 165                 self.inner.sign_channel_announcement(msg, secp_ctx)
 166         }
 167
 168         fn ready_channel(&mut self, channel_parameters: &ChannelTransactionParameters) {
 169                 self.inner.ready_channel(channel_parameters)
 170         }
 171 }
 172
 173 impl Sign for EnforcingSigner {}
 174
 175 impl Writeable for EnforcingSigner {
 176         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 177                 self.inner.write(writer)?;
 178                 let last = *self.last_commitment_number.lock().unwrap();
 179                 last.write(writer)?;
 180                 Ok(())
 181         }
 182 }
 183
 184 impl Readable for EnforcingSigner {
 185         fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 186                 let inner = Readable::read(reader)?;
 187                 let last_commitment_number = Readable::read(reader)?;
 188                 Ok(EnforcingSigner {
 189                         inner,
 190                         last_commitment_number: Arc::new(Mutex::new(last_commitment_number)),
 191                         revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)),
 192                         disable_revocation_policy_check: false,
 193                 })
 194         }
 195 }
 196
 197 impl EnforcingSigner {
 198         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 199                 commitment_tx.verify(&self.inner.get_channel_parameters().as_counterparty_broadcastable(),
 200                                      self.inner.counterparty_pubkeys(), self.inner.pubkeys(), secp_ctx)
 201                         .expect("derived different per-tx keys or built transaction")
 202         }
 203
 204         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 205                 commitment_tx.verify(&self.inner.get_channel_parameters().as_holder_broadcastable(),
 206                                      self.inner.pubkeys(), self.inner.counterparty_pubkeys(), secp_ctx)
 207                         .expect("derived different per-tx keys or built transaction")
 208         }
 209 }