Merge pull request #444 from lightning-signer/funding-script

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

diff --git a/lightning/src/chain/keysinterface.rs b/lightning/src/chain/keysinterface.rs
index fae609cc85daf22f6a7660b00711eb099cb34388..c001646263fdf0d7ae4e1f1c079ed02ab3b40135 100644 (file)
--- a/lightning/src/chain/keysinterface.rs
+++ b/lightning/src/chain/keysinterface.rs
@@ -24,7 +24,7 @@ use util::logger::Logger;
 use util::ser::Writeable;
 
 use ln::chan_utils;
-use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment};
+use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, make_funding_redeemscript};
 use ln::msgs;
 
 use std::sync::Arc;
@@ -142,7 +142,7 @@ pub trait ChannelKeys : Send {
        /// TODO: Document the things someone using this interface should enforce before signing.
        /// TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
        /// making the callee generate it via some util function we expose)!
-       fn sign_remote_commitment<T: secp256k1::Signing>(&self, channel_value_satoshis: u64, channel_funding_redeemscript: &Script, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
+       fn sign_remote_commitment<T: secp256k1::Signing>(&self, channel_value_satoshis: u64, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
 
        /// Create a signature for a (proposed) closing transaction.
        ///
@@ -157,6 +157,12 @@ pub trait ChannelKeys : Send {
        /// our counterparty may (though likely will not) close the channel on us for violating the
        /// protocol.
        fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
+
+       /// Set the remote funding key.  This is done immediately on incoming channels
+       /// and as soon as the channel is accepted on outgoing channels.
+       ///
+       /// Will be called before any signatures are applied.
+       fn set_remote_funding_pubkey(&mut self, key: &PublicKey);
 }
 
 #[derive(Clone)]
@@ -174,6 +180,8 @@ pub struct InMemoryChannelKeys {
        pub htlc_base_key: SecretKey,
        /// Commitment seed
        pub commitment_seed: [u8; 32],
+       /// Remote funding pubkey
+       pub remote_funding_pubkey: Option<PublicKey>,
 }
 
 impl ChannelKeys for InMemoryChannelKeys {
@@ -184,8 +192,13 @@ impl ChannelKeys for InMemoryChannelKeys {
        fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
        fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }
 
-       fn sign_remote_commitment<T: secp256k1::Signing>(&self, channel_value_satoshis: u64, channel_funding_redeemscript: &Script, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
+       fn sign_remote_commitment<T: secp256k1::Signing>(&self, channel_value_satoshis: u64, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
                if commitment_tx.input.len() != 1 { return Err(()); }
+
+               let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
+               let remote_funding_pubkey = self.remote_funding_pubkey.as_ref().expect("must set remote funding key before signing");
+               let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, remote_funding_pubkey);
+
                let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, channel_value_satoshis)[..]);
                let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
 
@@ -222,6 +235,11 @@ impl ChannelKeys for InMemoryChannelKeys {
                let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
                Ok(secp_ctx.sign(&msghash, &self.funding_key))
        }
+
+       fn set_remote_funding_pubkey(&mut self, key: &PublicKey) {
+               assert!(self.remote_funding_pubkey.is_none(), "Already set remote funding key");
+               self.remote_funding_pubkey = Some(*key);
+       }
 }
 
 impl_writeable!(InMemoryChannelKeys, 0, {
@@ -230,7 +248,8 @@ impl_writeable!(InMemoryChannelKeys, 0, {
        payment_base_key,
        delayed_payment_base_key,
        htlc_base_key,
-       commitment_seed
+       commitment_seed,
+       remote_funding_pubkey
 });
 
 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
@@ -379,6 +398,7 @@ impl KeysInterface for KeysManager {
                        delayed_payment_base_key,
                        htlc_base_key,
                        commitment_seed,
+                       remote_funding_pubkey: None,
                }
        }