1 // This file is Copyright its original authors, visible in version control
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
10 use ln::chan_utils::{HTLCOutputInCommitment, ChannelPublicKeys, HolderCommitmentTransaction, CommitmentTransaction, ChannelTransactionParameters, TrustedCommitmentTransaction};
11 use ln::{chan_utils, msgs};
12 use chain::keysinterface::{ChannelKeys, InMemoryChannelKeys};
15 use std::sync::{Mutex, Arc};
17 use bitcoin::blockdata::transaction::{Transaction, SigHashType};
18 use bitcoin::util::bip143;
20 use bitcoin::secp256k1;
21 use bitcoin::secp256k1::key::{SecretKey, PublicKey};
22 use bitcoin::secp256k1::{Secp256k1, Signature};
23 use util::ser::{Writeable, Writer, Readable};
25 use ln::msgs::DecodeError;
27 /// Initial value for revoked commitment downward counter
28 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
30 /// An implementation of ChannelKeys that enforces some policy checks.
32 /// Eventually we will probably want to expose a variant of this which would essentially
33 /// be what you'd want to run on a hardware wallet.
35 pub struct EnforcingChannelKeys {
36 pub inner: InMemoryChannelKeys,
37 pub last_commitment_number: Arc<Mutex<Option<u64>>>,
38 pub revoked_commitment: Arc<Mutex<u64>>,
41 impl EnforcingChannelKeys {
42 pub fn new(inner: InMemoryChannelKeys) -> Self {
45 last_commitment_number: Arc::new(Mutex::new(None)),
46 revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER))
50 pub fn new_with_revoked(inner: InMemoryChannelKeys, revoked_commitment: Arc<Mutex<u64>>) -> Self {
53 last_commitment_number: Arc::new(Mutex::new(None)),
59 impl ChannelKeys for EnforcingChannelKeys {
60 fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey {
61 self.inner.get_per_commitment_point(idx, secp_ctx)
64 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
65 println!("XXX revoke {} for {}", idx, self.inner.commitment_seed[0]);
68 let mut revoked = self.revoked_commitment.lock().unwrap();
69 assert!(idx == *revoked || idx == *revoked - 1, "can only revoke the current or next unrevoked commitment - trying {}, revoked {}", idx, *revoked);
72 self.inner.release_commitment_secret(idx)
75 fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
76 fn key_derivation_params(&self) -> (u64, u64) { self.inner.key_derivation_params() }
78 fn sign_counterparty_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
79 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
82 let mut last_commitment_number_guard = self.last_commitment_number.lock().unwrap();
83 let actual_commitment_number = commitment_tx.commitment_number();
84 let last_commitment_number = last_commitment_number_guard.unwrap_or(actual_commitment_number);
85 // These commitment numbers are backwards counting. We expect either the same as the previously encountered,
87 assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
88 *last_commitment_number_guard = Some(cmp::min(last_commitment_number, actual_commitment_number))
91 Ok(self.inner.sign_counterparty_commitment(commitment_tx, secp_ctx).unwrap())
94 fn sign_holder_commitment_and_htlcs<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
95 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
96 let commitment_txid = trusted_tx.txid();
97 let holder_csv = self.inner.counterparty_selected_contest_delay();
99 let revoked = self.revoked_commitment.lock().unwrap();
100 let commitment_number = trusted_tx.commitment_number();
101 println!("XXX sign {} for {}", commitment_number, self.inner.commitment_seed[0]);
102 if *revoked - 1 != commitment_number && *revoked - 2 != commitment_number {
103 println!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
104 *revoked, commitment_number, self.inner.commitment_seed[0]);
108 for (this_htlc, sig) in trusted_tx.htlcs().iter().zip(&commitment_tx.counterparty_htlc_sigs) {
109 assert!(this_htlc.transaction_output_index.is_some());
110 let keys = trusted_tx.keys();
111 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);
113 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc, &keys);
115 let sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, this_htlc.amount_msat / 1000, SigHashType::All)[..]);
116 secp_ctx.verify(&sighash, sig, &keys.countersignatory_htlc_key).unwrap();
119 // TODO: enforce the ChannelKeys contract - error if this commitment was already revoked
120 // TODO: need the commitment number
121 Ok(self.inner.sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
124 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
125 fn unsafe_sign_holder_commitment_and_htlcs<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
126 Ok(self.inner.unsafe_sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
129 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, ()> {
130 Ok(self.inner.sign_justice_transaction(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
133 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, ()> {
134 Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
137 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
138 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
141 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
142 self.inner.sign_channel_announcement(msg, secp_ctx)
145 fn ready_channel(&mut self, channel_parameters: &ChannelTransactionParameters) {
146 self.inner.ready_channel(channel_parameters)
151 impl Writeable for EnforcingChannelKeys {
152 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
153 self.inner.write(writer)?;
154 let last = *self.last_commitment_number.lock().unwrap();
160 impl Readable for EnforcingChannelKeys {
161 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
162 let inner: InMemoryChannelKeys = Readable::read(reader)?;
163 let last_commitment_number = Readable::read(reader)?;
164 Ok(EnforcingChannelKeys {
166 last_commitment_number: Arc::new(Mutex::new(last_commitment_number)),
167 revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)),
172 impl EnforcingChannelKeys {
173 fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
174 commitment_tx.verify(&self.inner.get_channel_parameters().as_counterparty_broadcastable(),
175 self.inner.counterparty_pubkeys(), self.inner.pubkeys(), secp_ctx)
176 .expect("derived different per-tx keys or built transaction")
179 fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
180 commitment_tx.verify(&self.inner.get_channel_parameters().as_holder_broadcastable(),
181 self.inner.pubkeys(), self.inner.counterparty_pubkeys(), secp_ctx)
182 .expect("derived different per-tx keys or built transaction")