Drop requirement that all ChannelKeys expose the payment_point

Author: TheBlueMatt

lightning/src/chain/keysinterface.rs

@@ -197,10 +197,6 @@ impl Readable for SpendableOutputDescriptor {
 pub trait ChannelKeys : Send+Clone {
 	/// Gets the local secret key for blinded revocation pubkey
 	fn revocation_base_key<'a>(&'a self) -> &'a SecretKey;
-	/// Gets the local secret key used in the to_remote output of remote commitment tx (ie the
-	/// output to us in transactions our counterparty broadcasts).
-	/// Also as part of obscured commitment number.
-	fn payment_key<'a>(&'a self) -> &'a SecretKey;
 	/// Gets the local secret key used in HTLC-Success/HTLC-Timeout txn and to_local output
 	fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey;
 	/// Gets the local htlc secret key used in commitment tx htlc outputs
@@ -415,7 +411,6 @@ impl InMemoryChannelKeys {
 
 impl ChannelKeys for InMemoryChannelKeys {
 	fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key }
-	fn payment_key(&self) -> &SecretKey { &self.payment_key }
 	fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key }
 	fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
 	fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }

lightning/src/ln/channel.rs

@@ -766,15 +766,14 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 	fn get_commitment_transaction_number_obscure_factor(&self) -> u64 {
 		let mut sha = Sha256::engine();
-		let our_payment_point = PublicKey::from_secret_key(&self.secp_ctx, self.local_keys.payment_key());
 
 		let their_payment_point = &self.their_pubkeys.as_ref().unwrap().payment_point.serialize();
 		if self.channel_outbound {
-			sha.input(&our_payment_point.serialize());
+			sha.input(&self.local_keys.pubkeys().payment_point.serialize());
 			sha.input(their_payment_point);
 		} else {
 			sha.input(their_payment_point);
-			sha.input(&our_payment_point.serialize());
+			sha.input(&self.local_keys.pubkeys().payment_point.serialize());
 		}
 		let res = Sha256::from_engine(sha).into_inner();
 
@@ -3317,7 +3316,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			max_accepted_htlcs: OUR_MAX_HTLCS,
 			funding_pubkey: local_keys.funding_pubkey,
 			revocation_basepoint: PublicKey::from_secret_key(&self.secp_ctx, self.local_keys.revocation_base_key()),
-			payment_point: PublicKey::from_secret_key(&self.secp_ctx, self.local_keys.payment_key()),
+			payment_point: local_keys.payment_point,
 			delayed_payment_basepoint: PublicKey::from_secret_key(&self.secp_ctx, self.local_keys.delayed_payment_base_key()),
 			htlc_basepoint: PublicKey::from_secret_key(&self.secp_ctx, self.local_keys.htlc_base_key()),
 			first_per_commitment_point: PublicKey::from_secret_key(&self.secp_ctx, &local_commitment_secret),
@@ -3351,7 +3350,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			max_accepted_htlcs: OUR_MAX_HTLCS,
 			funding_pubkey: local_keys.funding_pubkey,
 			revocation_basepoint: PublicKey::from_secret_key(&self.secp_ctx, self.local_keys.revocation_base_key()),
-			payment_point: PublicKey::from_secret_key(&self.secp_ctx, self.local_keys.payment_key()),
+			payment_point: local_keys.payment_point,
 			delayed_payment_basepoint: PublicKey::from_secret_key(&self.secp_ctx, self.local_keys.delayed_payment_base_key()),
 			htlc_basepoint: PublicKey::from_secret_key(&self.secp_ctx, self.local_keys.htlc_base_key()),
 			first_per_commitment_point: PublicKey::from_secret_key(&self.secp_ctx, &local_commitment_secret),

lightning/src/ln/channelmonitor.rs

@@ -1641,7 +1641,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 					self.remote_payment_script = {
 						// Note that the Network here is ignored as we immediately drop the address for the
 						// script_pubkey version
-						let payment_hash160 = WPubkeyHash::hash(&PublicKey::from_secret_key(&self.secp_ctx, &self.keys.payment_key()).serialize());
+						let payment_hash160 = WPubkeyHash::hash(&self.keys.pubkeys().payment_point.serialize());
 						Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&payment_hash160[..]).into_script()
 					};
 

lightning/src/ln/functional_tests.rs

@@ -4293,10 +4293,10 @@ macro_rules! check_spendable_outputs {
 									};
 									let secp_ctx = Secp256k1::new();
 									let keys = $keysinterface.derive_channel_keys($chan_value, key_derivation_params.0, key_derivation_params.1);
-									let remotepubkey = PublicKey::from_secret_key(&secp_ctx, &keys.payment_key());
+									let remotepubkey = keys.pubkeys().payment_point;
 									let witness_script = Address::p2pkh(&::bitcoin::PublicKey{compressed: true, key: remotepubkey}, Network::Testnet).script_pubkey();
 									let sighash = Message::from_slice(&bip143::SighashComponents::new(&spend_tx).sighash_all(&spend_tx.input[0], &witness_script, output.value)[..]).unwrap();
-									let remotesig = secp_ctx.sign(&sighash, &keys.payment_key());
+									let remotesig = secp_ctx.sign(&sighash, &keys.inner.payment_key);
 									spend_tx.input[0].witness.push(remotesig.serialize_der().to_vec());
 									spend_tx.input[0].witness[0].push(SigHashType::All as u8);
 									spend_tx.input[0].witness.push(remotepubkey.serialize().to_vec());

lightning/src/util/enforcing_trait_impls.rs

@@ -52,7 +52,6 @@ impl EnforcingChannelKeys {
 
 impl ChannelKeys for EnforcingChannelKeys {
 	fn revocation_base_key(&self) -> &SecretKey { self.inner.revocation_base_key() }
-	fn payment_key(&self) -> &SecretKey { self.inner.payment_key() }
 	fn delayed_payment_base_key(&self) -> &SecretKey { self.inner.delayed_payment_base_key() }
 	fn htlc_base_key(&self) -> &SecretKey { self.inner.htlc_base_key() }
 	fn commitment_seed(&self) -> &[u8; 32] { self.inner.commitment_seed() }