Onion messages v1

fuzz/src/chanmon_consistency.rs

@@ -54,6 +54,7 @@ use utils::test_logger::{self, Output};
 use utils::test_persister::TestPersister;
 
 use bitcoin::secp256k1::{PublicKey,SecretKey};
+use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::RecoverableSignature;
 use bitcoin::secp256k1::Secp256k1;
 
@@ -165,6 +166,14 @@ impl KeysInterface for KeyProvider {
 		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())
 	}
 
+	fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> {
+		let mut node_secret = self.get_node_secret(recipient)?;
+		if let Some(tweak) = tweak {
+			node_secret.mul_assign(tweak).map_err(|_| ())?;
+		}
+		Ok(SharedSecret::new(other_key, &node_secret))
+	}
+
 	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])
 	}

fuzz/src/full_stack.rs

@@ -51,6 +51,7 @@ use utils::test_logger;
 use utils::test_persister::TestPersister;
 
 use bitcoin::secp256k1::{PublicKey,SecretKey};
+use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::RecoverableSignature;
 use bitcoin::secp256k1::Secp256k1;
 
@@ -269,6 +270,14 @@ impl KeysInterface for KeyProvider {
 		Ok(self.node_secret.clone())
 	}
 
+	fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> {
+		let mut node_secret = self.get_node_secret(recipient)?;
+		if let Some(tweak) = tweak {
+			node_secret.mul_assign(tweak).map_err(|_| ())?;
+		}
+		Ok(SharedSecret::new(other_key, &node_secret))
+	}
+
 	fn get_inbound_payment_key_material(&self) -> KeyMaterial {
 		self.inbound_payment_key.clone()
 	}

lightning/src/chain/keysinterface.rs

@@ -27,6 +27,7 @@ use bitcoin::hash_types::WPubkeyHash;
 
 use bitcoin::secp256k1::{SecretKey, PublicKey};
 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature, Signing};
+use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::RecoverableSignature;
 use bitcoin::{secp256k1, Witness};
 
@@ -404,6 +405,12 @@ pub trait KeysInterface {
 	/// This method must return the same value each time it is called with a given `Recipient`
 	/// parameter.
 	fn get_node_secret(&self, recipient: Recipient) -> Result<SecretKey, ()>;
+	/// Gets the ECDH shared secret of our [`node secret`] and `other_key`, multiplying by `tweak` if
+	/// one is provided. Note that this tweak can be applied to `other_key` instead of our node
+	/// secret, though this is less efficient.
+	///
+	/// [`node secret`]: Self::get_node_secret
+	fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()>;
 	/// Get a script pubkey which we send funds to when claiming on-chain contestable outputs.
 	///
 	/// This method should return a different value each time it is called, to avoid linking
@@ -1133,6 +1140,14 @@ impl KeysInterface for KeysManager {
 		}
 	}
 
+	fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> {
+		let mut node_secret = self.get_node_secret(recipient)?;
+		if let Some(tweak) = tweak {
+			node_secret.mul_assign(tweak).map_err(|_| ())?;
+		}
+		Ok(SharedSecret::new(other_key, &node_secret))
+	}
+
 	fn get_inbound_payment_key_material(&self) -> KeyMaterial {
 		self.inbound_payment_key.clone()
 	}
@@ -1217,6 +1232,14 @@ impl KeysInterface for PhantomKeysManager {
 		}
 	}
 
+	fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> {
+		let mut node_secret = self.get_node_secret(recipient)?;
+		if let Some(tweak) = tweak {
+			node_secret.mul_assign(tweak).map_err(|_| ())?;
+		}
+		Ok(SharedSecret::new(other_key, &node_secret))
+	}
+
 	fn get_inbound_payment_key_material(&self) -> KeyMaterial {
 		self.inbound_payment_key.clone()
 	}

lightning/src/lib.rs

@@ -17,7 +17,7 @@
 //! figure out how best to make networking happen/timers fire/things get written to disk/keys get
 //! generated/etc. This makes it a good candidate for tight integration into an existing wallet
 //! instead of having a rather-separate lightning appendage to a wallet.
-//! 
+//!
 //! `default` features are:
 //!
 //! * `std` - enables functionalities which require `std`, including `std::io` trait implementations and things which utilize time
@@ -76,6 +76,8 @@ pub mod util;
 pub mod chain;
 pub mod ln;
 pub mod routing;
+#[allow(unused)]
+mod onion_message; // To be exposed after sending/receiving OMs is supported in PeerManager.
 
 #[cfg(feature = "std")]
 /// Re-export of either `core2::io` or `std::io`, depending on the `std` feature flag.

lightning/src/ln/channel.rs

@@ -6583,6 +6583,7 @@ mod tests {
 	use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
 	use bitcoin::secp256k1::ffi::Signature as FFISignature;
 	use bitcoin::secp256k1::{SecretKey,PublicKey};
+	use bitcoin::secp256k1::ecdh::SharedSecret;
 	use bitcoin::secp256k1::ecdsa::RecoverableSignature;
 	use bitcoin::hashes::sha256::Hash as Sha256;
 	use bitcoin::hashes::Hash;
@@ -6621,6 +6622,7 @@ mod tests {
 		type Signer = InMemorySigner;
 
 		fn get_node_secret(&self, _recipient: Recipient) -> Result<SecretKey, ()> { panic!(); }
+		fn ecdh(&self, _recipient: Recipient, _other_key: &PublicKey, _tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> { panic!(); }
 		fn get_inbound_payment_key_material(&self) -> KeyMaterial { panic!(); }
 		fn get_destination_script(&self) -> Script {
 			let secp_ctx = Secp256k1::signing_only();

lightning/src/ln/channelmanager.rs

@@ -2159,7 +2159,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 			}
 		}
 
-		let next_hop = match onion_utils::decode_next_hop(shared_secret, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac, msg.payment_hash) {
+		let next_hop = match onion_utils::decode_next_payment_hop(shared_secret, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac, msg.payment_hash) {
 			Ok(res) => res,
 			Err(onion_utils::OnionDecodeErr::Malformed { err_msg, err_code }) => {
 				return_malformed_err!(err_msg, err_code);
@@ -3058,7 +3058,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 												let phantom_secret_res = self.keys_manager.get_node_secret(Recipient::PhantomNode);
 												if phantom_secret_res.is_ok() && fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, short_chan_id) {
 													let phantom_shared_secret = SharedSecret::new(&onion_packet.public_key.unwrap(), &phantom_secret_res.unwrap()).secret_bytes();
-													let next_hop = match onion_utils::decode_next_hop(phantom_shared_secret, &onion_packet.hop_data, onion_packet.hmac, payment_hash) {
+													let next_hop = match onion_utils::decode_next_payment_hop(phantom_shared_secret, &onion_packet.hop_data, onion_packet.hmac, payment_hash) {
 														Ok(res) => res,
 														Err(onion_utils::OnionDecodeErr::Malformed { err_msg, err_code }) => {
 															let sha256_of_onion = Sha256::hash(&onion_packet.hop_data).into_inner();

lightning/src/ln/mod.rs

@@ -43,7 +43,7 @@ pub mod channel;
 #[cfg(not(fuzzing))]
 pub(crate) mod channel;
 
-mod onion_utils;
+pub(crate) mod onion_utils;
 pub mod wire;
 
 // Older rustc (which we support) refuses to let us call the get_payment_preimage_hash!() macro

lightning/src/ln/msgs.rs

@@ -31,6 +31,8 @@ use bitcoin::blockdata::script::Script;
 use bitcoin::hash_types::{Txid, BlockHash};
 
 use ln::features::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, NodeFeatures};
+use ln::onion_utils;
+use onion_message;
 
 use prelude::*;
 use core::fmt;
@@ -40,7 +42,7 @@ use io_extras::read_to_end;
 
 use util::events::MessageSendEventsProvider;
 use util::logger;
-use util::ser::{Readable, Writeable, Writer, FixedLengthReader, HighZeroBytesDroppedVarInt, Hostname};
+use util::ser::{LengthReadable, Readable, ReadableArgs, Writeable, Writer, FixedLengthReader, HighZeroBytesDroppedVarInt, Hostname};
 
 use ln::{PaymentPreimage, PaymentHash, PaymentSecret};
 
@@ -304,6 +306,14 @@ pub struct UpdateAddHTLC {
 	pub(crate) onion_routing_packet: OnionPacket,
 }
 
+ /// An onion message to be sent or received from a peer
+#[derive(Clone, Debug, PartialEq)]
+pub struct OnionMessage {
+	/// Used in decrypting the onion packet's payload.
+	pub blinding_point: PublicKey,
+	pub(crate) onion_routing_packet: onion_message::Packet,
+}
+
 /// An update_fulfill_htlc message to be sent or received from a peer
 #[derive(Clone, Debug, PartialEq)]
 pub struct UpdateFulfillHTLC {
@@ -993,6 +1003,18 @@ pub(crate) struct OnionPacket {
 	pub(crate) hmac: [u8; 32],
 }
 
+impl onion_utils::Packet for OnionPacket {
+	type Data = onion_utils::FixedSizeOnionPacket;
+	fn new(pubkey: PublicKey, hop_data: onion_utils::FixedSizeOnionPacket, hmac: [u8; 32]) -> Self {
+		Self {
+			version: 0,
+			public_key: Ok(pubkey),
+			hop_data: hop_data.0,
+			hmac,
+		}
+	}
+}
+
 impl PartialEq for OnionPacket {
 	fn eq(&self, other: &OnionPacket) -> bool {
 		for (i, j) in self.hop_data.iter().zip(other.hop_data.iter()) {
@@ -1327,6 +1349,29 @@ impl_writeable_msg!(UpdateAddHTLC, {
 	onion_routing_packet
 }, {});
 
+impl Readable for OnionMessage {
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+		let blinding_point: PublicKey = Readable::read(r)?;
+		let len: u16 = Readable::read(r)?;
+		let mut packet_reader = FixedLengthReader::new(r, len as u64);
+		let onion_routing_packet: onion_message::Packet = <onion_message::Packet as LengthReadable>::read(&mut packet_reader)?;
+		Ok(Self {
+			blinding_point,
+			onion_routing_packet,
+		})
+	}
+}
+
+impl Writeable for OnionMessage {
+	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+		self.blinding_point.write(w)?;
+		let onion_packet_len = self.onion_routing_packet.serialized_length();
+		(onion_packet_len as u16).write(w)?;
+		self.onion_routing_packet.write(w)?;
+		Ok(())
+	}
+}
+
 impl Writeable for FinalOnionHopData {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 		self.payment_secret.0.write(w)?;
@@ -1372,6 +1417,14 @@ impl Writeable for OnionHopData {
 	}
 }
 
+// ReadableArgs because we need onion_utils::decode_next_hop to accommodate payment packets and
+// onion message packets.
+impl ReadableArgs<()> for OnionHopData {
+	fn read<R: Read>(r: &mut R, _arg: ()) -> Result<Self, DecodeError> {
+		<Self as Readable>::read(r)
+	}
+}
+
 impl Readable for OnionHopData {
 	fn read<R: Read>(mut r: &mut R) -> Result<Self, DecodeError> {
 		use bitcoin::consensus::encode::{Decodable, Error, VarInt};