Add NodeSigner::sign_gossip_message

Adds signing capability to NodeSigner for all gossip messages that
require a node signature.

Author: wpaulino

fuzz/src/chanmon_consistency.rs

@@ -29,6 +29,7 @@ use bitcoin::network::constants::Network;
 
 use bitcoin::hashes::Hash as TraitImport;
 use bitcoin::hashes::sha256::Hash as Sha256;
+use bitcoin::hashes::sha256d::Hash as Sha256dHash;
 use bitcoin::hash_types::{BlockHash, WPubkeyHash};
 
 use lightning::chain;
@@ -54,10 +55,9 @@ use lightning::routing::router::{InFlightHtlcs, Route, RouteHop, RouteParameters
 use crate::utils::test_logger::{self, Output};
 use crate::utils::test_persister::TestPersister;
 
-use bitcoin::secp256k1::{PublicKey, SecretKey, Scalar};
+use bitcoin::secp256k1::{Message, PublicKey, SecretKey, Scalar, Secp256k1};
 use bitcoin::secp256k1::ecdh::SharedSecret;
-use bitcoin::secp256k1::ecdsa::RecoverableSignature;
-use bitcoin::secp256k1::Secp256k1;
+use bitcoin::secp256k1::ecdsa::{RecoverableSignature, Signature};
 
 use std::mem;
 use std::cmp::{self, Ordering};
@@ -174,23 +174,23 @@ impl chain::Watch<EnforcingSigner> for TestChainMonitor {
 }
 
 struct KeyProvider {
-	node_id: u8,
+	node_secret: SecretKey,
 	rand_bytes_id: atomic::AtomicU32,
 	enforcement_states: Mutex<HashMap<[u8;32], Arc<Mutex<EnforcementState>>>>,
 }
 
 impl EntropySource for KeyProvider {
 	fn get_secure_random_bytes(&self) -> [u8; 32] {
 		let id = self.rand_bytes_id.fetch_add(1, atomic::Ordering::Relaxed);
-		let mut res = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, self.node_id];
+		let mut res = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, self.node_secret[31]];
 		res[30-4..30].copy_from_slice(&id.to_le_bytes());
 		res
 	}
 }
 
 impl NodeSigner for KeyProvider {
 	fn get_node_secret(&self, _recipient: Recipient) -> Result<SecretKey, ()> {
-		Ok(SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, self.node_id]).unwrap())
+		Ok(self.node_secret.clone())
 	}
 
 	fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()> {
@@ -207,12 +207,18 @@ impl NodeSigner for KeyProvider {
 	}
 
 	fn get_inbound_payment_key_material(&self) -> KeyMaterial {
-		KeyMaterial([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, self.node_id])
+		KeyMaterial([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, self.node_secret[31]])
 	}
 
 	fn sign_invoice(&self, _hrp_bytes: &[u8], _invoice_data: &[u5], _recipient: Recipient) -> Result<RecoverableSignature, ()> {
 		unreachable!()
 	}
+
+	fn sign_gossip_message(&self, msg: lightning::ln::msgs::UnsignedGossipMessage) -> Result<Signature, ()> {
+		let msg_hash = Message::from_slice(&Sha256dHash::hash(&msg.encode()[..])[..]).map_err(|_| ())?;
+		let secp_ctx = Secp256k1::signing_only();
+		Ok(secp_ctx.sign_ecdsa(&msg_hash, &self.node_secret))
+	}
 }
 
 impl SignerProvider for KeyProvider {
@@ -229,12 +235,12 @@ impl SignerProvider for KeyProvider {
 		let keys = InMemorySigner::new(
 			&secp_ctx,
 			self.get_node_secret(Recipient::Node).unwrap(),
-			SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, self.node_id]).unwrap(),
-			SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, self.node_id]).unwrap(),
-			SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, self.node_id]).unwrap(),
-			SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, self.node_id]).unwrap(),
-			SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, self.node_id]).unwrap(),
-			[id, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, self.node_id],
+			SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, self.node_secret[31]]).unwrap(),
+			SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, self.node_secret[31]]).unwrap(),
+			SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, self.node_secret[31]]).unwrap(),
+			SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, self.node_secret[31]]).unwrap(),
+			SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, self.node_secret[31]]).unwrap(),
+			[id, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, self.node_secret[31]],
 			channel_value_satoshis,
 			channel_keys_id,
 		);
@@ -257,14 +263,14 @@ impl SignerProvider for KeyProvider {
 
 	fn get_destination_script(&self) -> Script {
 		let secp_ctx = Secp256k1::signing_only();
-		let channel_monitor_claim_key = SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, self.node_id]).unwrap();
+		let channel_monitor_claim_key = SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, self.node_secret[31]]).unwrap();
 		let our_channel_monitor_claim_key_hash = WPubkeyHash::hash(&PublicKey::from_secret_key(&secp_ctx, &channel_monitor_claim_key).serialize());
 		Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&our_channel_monitor_claim_key_hash[..]).into_script()
 	}
 
 	fn get_shutdown_scriptpubkey(&self) -> ShutdownScript {
 		let secp_ctx = Secp256k1::signing_only();
-		let secret_key = SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, self.node_id]).unwrap();
+		let secret_key = SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, self.node_secret[31]]).unwrap();
 		let pubkey_hash = WPubkeyHash::hash(&PublicKey::from_secret_key(&secp_ctx, &secret_key).serialize());
 		ShutdownScript::new_p2wpkh(&pubkey_hash)
 	}
@@ -402,7 +408,8 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out) {
 	macro_rules! make_node {
 		($node_id: expr, $fee_estimator: expr) => { {
 			let logger: Arc<dyn Logger> = Arc::new(test_logger::TestLogger::new($node_id.to_string(), out.clone()));
-			let keys_manager = Arc::new(KeyProvider { node_id: $node_id, rand_bytes_id: atomic::AtomicU32::new(0), enforcement_states: Mutex::new(HashMap::new()) });
+			let node_secret = SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, $node_id]).unwrap();
+			let keys_manager = Arc::new(KeyProvider { node_secret, rand_bytes_id: atomic::AtomicU32::new(0), enforcement_states: Mutex::new(HashMap::new()) });
 			let monitor = Arc::new(TestChainMonitor::new(broadcast.clone(), logger.clone(), $fee_estimator.clone(),
 				Arc::new(TestPersister {
 					update_ret: Mutex::new(ChannelMonitorUpdateStatus::Completed)

fuzz/src/full_stack.rs

@@ -26,6 +26,7 @@ use bitcoin::network::constants::Network;
 use bitcoin::hashes::Hash as TraitImport;
 use bitcoin::hashes::HashEngine as TraitImportEngine;
 use bitcoin::hashes::sha256::Hash as Sha256;
+use bitcoin::hashes::sha256d::Hash as Sha256dHash;
 use bitcoin::hash_types::{Txid, BlockHash, WPubkeyHash};
 
 use lightning::chain;
@@ -47,15 +48,14 @@ use lightning::util::errors::APIError;
 use lightning::util::events::Event;
 use lightning::util::enforcing_trait_impls::{EnforcingSigner, EnforcementState};
 use lightning::util::logger::Logger;
-use lightning::util::ser::ReadableArgs;
+use lightning::util::ser::{ReadableArgs, Writeable};
 
 use crate::utils::test_logger;
 use crate::utils::test_persister::TestPersister;
 
-use bitcoin::secp256k1::{PublicKey, SecretKey, Scalar};
+use bitcoin::secp256k1::{Message, PublicKey, SecretKey, Scalar, Secp256k1};
 use bitcoin::secp256k1::ecdh::SharedSecret;
-use bitcoin::secp256k1::ecdsa::RecoverableSignature;
-use bitcoin::secp256k1::Secp256k1;
+use bitcoin::secp256k1::ecdsa::{RecoverableSignature, Signature};
 
 use std::cell::RefCell;
 use hashbrown::{HashMap, hash_map};
@@ -317,6 +317,12 @@ impl NodeSigner for KeyProvider {
 	fn sign_invoice(&self, _hrp_bytes: &[u8], _invoice_data: &[u5], _recipient: Recipient) -> Result<RecoverableSignature, ()> {
 		unreachable!()
 	}
+
+	fn sign_gossip_message(&self, msg: lightning::ln::msgs::UnsignedGossipMessage) -> Result<Signature, ()> {
+		let msg_hash = Message::from_slice(&Sha256dHash::hash(&msg.encode()[..])[..]).map_err(|_| ())?;
+		let secp_ctx = Secp256k1::signing_only();
+		Ok(secp_ctx.sign_ecdsa(&msg_hash, &self.node_secret))
+	}
 }
 
 impl SignerProvider for KeyProvider {

fuzz/src/onion_message.rs

@@ -122,6 +122,10 @@ impl NodeSigner for KeyProvider {
 	fn sign_invoice(&self, _hrp_bytes: &[u8], _invoice_data: &[u5], _recipient: Recipient) -> Result<RecoverableSignature, ()> {
 		unreachable!()
 	}
+
+	fn sign_gossip_message(&self, _msg: lightning::ln::msgs::UnsignedGossipMessage) -> Result<bitcoin::secp256k1::ecdsa::Signature, ()> {
+		unreachable!()
+	}
 }
 
 impl SignerProvider for KeyProvider {

lightning/src/chain/keysinterface.rs

@@ -41,7 +41,7 @@ use crate::chain::transaction::OutPoint;
 use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
 use crate::ln::{chan_utils, PaymentPreimage};
 use crate::ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, HolderCommitmentTransaction, ChannelTransactionParameters, CommitmentTransaction, ClosingTransaction};
-use crate::ln::msgs::UnsignedChannelAnnouncement;
+use crate::ln::msgs::{UnsignedChannelAnnouncement, UnsignedGossipMessage};
 use crate::ln::script::ShutdownScript;
 
 use crate::prelude::*;
@@ -494,6 +494,14 @@ pub trait NodeSigner {
 	///
 	/// Errors if the [`Recipient`] variant is not supported by the implementation.
 	fn sign_invoice(&self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient) -> Result<RecoverableSignature, ()>;
+
+	/// Sign a gossip message.
+	///
+	/// Note that if this fails, LDK may panic and the message will not be broadcast to the network
+	/// or a possible channel counterparty. If LDK panics, the error should be resolved to allow the
+	/// message to be broadcast, as otherwise it may prevent one from receiving funds over the
+	/// corresponding channel.
+	fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()>;
 }
 
 /// A trait that can return signer instances for individual channels.
@@ -1290,6 +1298,11 @@ impl NodeSigner for KeysManager {
 		};
 		Ok(self.secp_ctx.sign_ecdsa_recoverable(&hash_to_message!(&Sha256::hash(&preimage)), &secret))
 	}
+
+	fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()> {
+		let msg_hash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
+		Ok(sign(&self.secp_ctx, &msg_hash, &self.node_secret))
+	}
 }
 
 impl SignerProvider for KeysManager {
@@ -1394,6 +1407,10 @@ impl NodeSigner for PhantomKeysManager {
 		let secret = self.get_node_secret(recipient)?;
 		Ok(self.inner.secp_ctx.sign_ecdsa_recoverable(&hash_to_message!(&Sha256::hash(&preimage)), &secret))
 	}
+
+	fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()> {
+		self.inner.sign_gossip_message(msg)
+	}
 }
 
 impl SignerProvider for PhantomKeysManager {

lightning/src/ln/msgs.rs

@@ -632,6 +632,25 @@ impl Readable for NetAddress {
 	}
 }
 
+/// Represents the set of gossip messages that require a signature from a node's identity key.
+pub enum UnsignedGossipMessage<'a> {
+	/// An unsigned channel announcement.
+	ChannelAnnouncement(&'a UnsignedChannelAnnouncement),
+	/// An unsigned channel update.
+	ChannelUpdate(&'a UnsignedChannelUpdate),
+	/// An unsigned node announcement.
+	NodeAnnouncement(&'a UnsignedNodeAnnouncement)
+}
+
+impl<'a> Writeable for UnsignedGossipMessage<'a> {
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+		match self {
+			UnsignedGossipMessage::ChannelAnnouncement(ref msg) => msg.write(writer),
+			UnsignedGossipMessage::ChannelUpdate(ref msg) => msg.write(writer),
+			UnsignedGossipMessage::NodeAnnouncement(ref msg) => msg.write(writer),
+		}
+	}
+}
 
 /// The unsigned part of a [`node_announcement`] message.
 ///

lightning/src/util/test_utils.rs

@@ -659,6 +659,10 @@ impl NodeSigner for TestKeysInterface {
 	fn sign_invoice(&self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient) -> Result<RecoverableSignature, ()> {
 		self.backing.sign_invoice(hrp_bytes, invoice_data, recipient)
 	}
+
+	fn sign_gossip_message(&self, msg: msgs::UnsignedGossipMessage) -> Result<Signature, ()> {
+		self.backing.sign_gossip_message(msg)
+    }
 }
 
 impl SignerProvider for TestKeysInterface {