Changes to create fresh destination scripts

Author: vss96

lightning/src/chain/channelmonitor.rs

@@ -2922,6 +2922,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 				spendable_output =  Some(SpendableOutputDescriptor::StaticOutput {
 					outpoint: OutPoint { txid: tx.txid(), index: i as u16 },
 					output: outp.clone(),
+					channel_keys_id: self.channel_keys_id,
 				});
 				break;
 			}
@@ -2952,6 +2953,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 				spendable_output = Some(SpendableOutputDescriptor::StaticOutput {
 					outpoint: OutPoint { txid: tx.txid(), index: i as u16 },
 					output: outp.clone(),
+					channel_keys_id: self.channel_keys_id,
 				});
 				break;
 			}

lightning/src/chain/keysinterface.rs

@@ -136,6 +136,8 @@ pub enum SpendableOutputDescriptor {
 		outpoint: OutPoint,
 		/// The output which is referenced by the given outpoint.
 		output: TxOut,
+		/// Key which is used to derive child keys
+		channel_keys_id: [u8; 32]
 	},
 	/// An output to a P2WSH script which can be spent with a single signature after a CSV delay.
 	///
@@ -180,6 +182,7 @@ impl_writeable_tlv_based_enum!(SpendableOutputDescriptor,
 	(0, StaticOutput) => {
 		(0, outpoint, required),
 		(2, output, required),
+		(4, channel_keys_id, required),
 	},
 ;
 	(1, DelayedPaymentOutput),
@@ -814,8 +817,7 @@ pub struct KeysManager {
 	secp_ctx: Secp256k1<secp256k1::All>,
 	node_secret: SecretKey,
 	inbound_payment_key: KeyMaterial,
-	destination_script: Script,
-	shutdown_pubkey: PublicKey,
+	shutdown_pubkey: ExtendedPubKey,
 	channel_master_key: ExtendedPrivKey,
 	channel_child_index: AtomicUsize,
 
@@ -854,17 +856,8 @@ impl KeysManager {
 		match ExtendedPrivKey::new_master(Network::Testnet, seed) {
 			Ok(master_key) => {
 				let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
-				let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
-					Ok(destination_key) => {
-						let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes());
-						Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
-						              .push_slice(&wpubkey_hash.into_inner())
-						              .into_script()
-					},
-					Err(_) => panic!("Your RNG is busted"),
-				};
 				let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
-					Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
+					Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key),
 					Err(_) => panic!("Your RNG is busted"),
 				};
 				let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
@@ -882,8 +875,6 @@ impl KeysManager {
 					secp_ctx,
 					node_secret,
 					inbound_payment_key: KeyMaterial(inbound_pmt_key_bytes),
-
-					destination_script,
 					shutdown_pubkey,
 
 					channel_master_key,
@@ -1000,7 +991,7 @@ impl KeysManager {
 					input_value += descriptor.output.value;
 					if !output_set.insert(descriptor.outpoint) { return Err(()); }
 				},
-				SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
+				SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output, .. } => {
 					input.push(TxIn {
 						previous_output: outpoint.into_bitcoin_outpoint(),
 						script_sig: Script::new(),
@@ -1043,12 +1034,25 @@ impl KeysManager {
 					}
 					spend_tx.input[input_idx].witness = keys_cache.as_ref().unwrap().0.sign_dynamic_p2wsh_input(&spend_tx, input_idx, &descriptor, &secp_ctx)?;
 				},
-				SpendableOutputDescriptor::StaticOutput { ref output, .. } => {
-					let derivation_idx = if output.script_pubkey == self.destination_script {
+				SpendableOutputDescriptor::StaticOutput { ref output, channel_keys_id,.. } => {
+					let derivation_idx = byte_utils::slice_to_be64(&channel_keys_id[0..8]);
+					let destination_script = match self.channel_master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(derivation_idx as u32).expect("key space exhausted")){
+						Ok(destination_key) => {
+									let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes());
+									Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
+									              .push_slice(&wpubkey_hash.into_inner())
+									              .into_script()
+								},
+						Err(_) => panic!("Your RNG is busted"),
+					};
+					
+					
+					let derivation_idx = if output.script_pubkey == destination_script {
 						1
 					} else {
 						2
 					};
+					
 					let secret = {
 						// Note that when we aren't serializing the key, network doesn't matter
 						match ExtendedPrivKey::new_master(Network::Testnet, &self.seed) {
@@ -1063,7 +1067,7 @@ impl KeysManager {
 					};
 					let pubkey = ExtendedPubKey::from_private(&secp_ctx, &secret).public_key;
 					if derivation_idx == 2 {
-						assert_eq!(pubkey.key, self.shutdown_pubkey);
+						assert_eq!(pubkey.key, self.shutdown_pubkey.public_key.key);
 					}
 					let witness_script = bitcoin::Address::p2pkh(&pubkey, Network::Testnet).script_pubkey();
 					let payment_script = bitcoin::Address::p2wpkh(&pubkey, Network::Testnet).expect("uncompressed key found").script_pubkey();
@@ -1101,11 +1105,11 @@ impl KeysInterface for KeysManager {
 	}
 
 	fn get_destination_script(&self) -> Script {
-		self.destination_script.clone()
+		bitcoin::Address::p2wpkh(&::bitcoin::PublicKey{compressed: true, key: self.shutdown_pubkey.public_key.key}, Network::Testnet).unwrap().script_pubkey()
 	}
 
 	fn get_shutdown_scriptpubkey(&self) -> ShutdownScript {
-		ShutdownScript::new_p2wpkh_from_pubkey(self.shutdown_pubkey.clone())
+		ShutdownScript::new_p2wpkh_from_pubkey(self.shutdown_pubkey.public_key.key.clone())
 	}
 
 	fn get_channel_signer(&self, _inbound: bool, channel_value_satoshis: u64) -> Self::Signer {