From 7bd8f8cadb8eceb4d92ce4a211fa5a341ca97fff Mon Sep 17 00:00:00 2001 From: Valentine Wallace Date: Thu, 26 May 2022 17:36:32 -0700 Subject: [PATCH] onion_utils: add next_hop_packet_pubkey method To get the next hop's packet's pubkey. This will be used to DRY onion message forwarding in the upcoming Onion Messages PR #1503 --- lightning/src/ln/channelmanager.rs | 18 +++--------------- lightning/src/ln/onion_utils.rs | 11 +++++++++++ 2 files changed, 14 insertions(+), 15 deletions(-) diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs index c787cedfa..0250efe22 100644 --- a/lightning/src/ln/channelmanager.rs +++ b/lightning/src/ln/channelmanager.rs @@ -24,7 +24,7 @@ use bitcoin::blockdata::transaction::Transaction; use bitcoin::blockdata::constants::genesis_block; use bitcoin::network::constants::Network; -use bitcoin::hashes::{Hash, HashEngine}; +use bitcoin::hashes::Hash; use bitcoin::hashes::sha256::Hash as Sha256; use bitcoin::hashes::sha256d::Hash as Sha256dHash; use bitcoin::hash_types::{BlockHash, Txid}; @@ -2164,22 +2164,10 @@ impl ChannelMana } }, onion_utils::Hop::Forward { next_hop_data, next_hop_hmac, new_packet_bytes } => { - let mut new_pubkey = msg.onion_routing_packet.public_key.unwrap(); - - let blinding_factor = { - let mut sha = Sha256::engine(); - sha.input(&new_pubkey.serialize()[..]); - sha.input(&shared_secret); - Sha256::from_engine(sha).into_inner() - }; - - let public_key = if let Err(e) = new_pubkey.mul_assign(&self.secp_ctx, &blinding_factor[..]) { - Err(e) - } else { Ok(new_pubkey) }; - + let new_pubkey = msg.onion_routing_packet.public_key.unwrap(); let outgoing_packet = msgs::OnionPacket { version: 0, - public_key, + public_key: onion_utils::next_hop_packet_pubkey(&self.secp_ctx, new_pubkey, &shared_secret), hop_data: new_packet_bytes, hmac: next_hop_hmac.clone(), }; diff --git a/lightning/src/ln/onion_utils.rs b/lightning/src/ln/onion_utils.rs index 1df374d7e..b223a344d 100644 --- a/lightning/src/ln/onion_utils.rs +++ b/lightning/src/ln/onion_utils.rs @@ -74,6 +74,17 @@ pub(super) fn gen_ammag_from_shared_secret(shared_secret: &[u8]) -> [u8; 32] { Hmac::from_engine(hmac).into_inner() } +pub(super) fn next_hop_packet_pubkey(secp_ctx: &Secp256k1, mut packet_pubkey: PublicKey, packet_shared_secret: &[u8; 32]) -> Result { + let blinding_factor = { + let mut sha = Sha256::engine(); + sha.input(&packet_pubkey.serialize()[..]); + sha.input(packet_shared_secret); + Sha256::from_engine(sha).into_inner() + }; + + packet_pubkey.mul_assign(secp_ctx, &blinding_factor[..]).map(|_| packet_pubkey) +} + // can only fail if an intermediary hop has an invalid public key or session_priv is invalid #[inline] pub(super) fn construct_onion_keys_callback (secp_ctx: &Secp256k1, path: &Vec, session_priv: &SecretKey, mut callback: FType) -> Result<(), secp256k1::Error> { -- 2.39.5