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  34 /// - When signing, the holder transaction has not been revoked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