Move justice transaction signature behind ChanSigner

[rust-lightning] / lightning / src / chain / keysinterface.rs

diff --git a/lightning/src/chain/keysinterface.rs b/lightning/src/chain/keysinterface.rs
index 9ed28e12fe8e983dc40f3a2abb7d00a36a018763..415fb420ac6b5d418b277872aae91477f654c27f 100644 (file)
--- a/lightning/src/chain/keysinterface.rs
+++ b/lightning/src/chain/keysinterface.rs
@@ -2,7 +2,7 @@
 //! spendable on-chain outputs which the user owns and is responsible for using just as any other
 //! on-chain output which is theirs.
 
-use bitcoin::blockdata::transaction::{Transaction, OutPoint, TxOut};
+use bitcoin::blockdata::transaction::{Transaction, OutPoint, TxOut, SigHashType};
 use bitcoin::blockdata::script::{Script, Builder};
 use bitcoin::blockdata::opcodes;
 use bitcoin::network::constants::Network;
@@ -248,6 +248,27 @@ pub trait ChannelKeys : Send+Clone {
        /// return value must contain a signature.
        fn sign_local_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, local_csv: u16, secp_ctx: &Secp256k1<T>) -> Result<Vec<Option<Signature>>, ()>;
 
+       /// Create a signature for a transaction spending an HTLC or commitment transaction output
+       /// when our counterparty broadcast an old state.
+       ///
+       /// Justice transaction may claim multiples outputs at same time if timelock are similar.
+       /// It may be called multiples time for same output(s) if a fee-bump is needed with regards
+       /// to an upcoming timelock expiration.
+       ///
+       /// Witness_script is a revokable witness script as defined in BOLT3 for `to_local`/HTLC
+       /// outputs.
+       ///
+       /// Input index is a pointer towards outpoint spent, commited by sigs (BIP 143).
+       ///
+       /// Amount is value of the output spent by this input, committed by sigs (BIP 143).
+       ///
+       /// Per_commitment key is revocation secret such as provided by remote party while
+       /// revocating detected onchain transaction. It's not a _local_ secret key, therefore
+       /// it may cross interfaces, a node compromise won't allow to spend revoked output without
+       /// also compromissing revocation key.
+       //TODO: dry-up witness_script and pass pubkeys
+       fn sign_justice_transaction<T: secp256k1::Signing>(&self, justice_tx: &Transaction, input: usize, witness_script: &Script, amount: u64, per_commitment_key: &SecretKey, revocation_pubkey: &PublicKey, is_htlc: bool, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
+
        /// Create a signature for a (proposed) closing transaction.
        ///
        /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
@@ -396,6 +417,15 @@ impl ChannelKeys for InMemoryChannelKeys {
                local_commitment_tx.get_htlc_sigs(&self.htlc_base_key, local_csv, secp_ctx)
        }
 
+       fn sign_justice_transaction<T: secp256k1::Signing>(&self, justice_tx: &Transaction, input: usize, witness_script: &Script, amount: u64, per_commitment_key: &SecretKey, revocation_pubkey: &PublicKey, is_htlc: bool, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
+               if let Ok(revocation_key) = chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) {
+                       let sighash_parts = bip143::SighashComponents::new(&justice_tx);
+                       let sighash = hash_to_message!(&sighash_parts.sighash_all(&justice_tx.input[input], &witness_script, amount)[..]);
+                       return Ok(secp_ctx.sign(&sighash, &revocation_key))
+               }
+               Err(())
+       }
+
        fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
                if closing_tx.input.len() != 1 { return Err(()); }
                if closing_tx.input[0].witness.len() != 0 { return Err(()); }