X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fonion_message%2Fblinded_route.rs;h=8a8d9924f9fb0ce33fcaca28602ff29a8598816d;hb=d6aa1bc85a537e2f1e61da3edb50bc24fcd80f7e;hp=9f1d8db46dd84d3477600e1d5a19015b3cb9e6aa;hpb=ee2f1a929ed427c5b2f963a3d13da2fec1a1cc24;p=rust-lightning

diff --git a/lightning/src/onion_message/blinded_route.rs b/lightning/src/onion_message/blinded_route.rs
index 9f1d8db4..8a8d9924 100644
--- a/lightning/src/onion_message/blinded_route.rs
+++ b/lightning/src/onion_message/blinded_route.rs
@@ -9,44 +9,52 @@
 
 //! Creating blinded routes and related utilities live here.
 
-use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
+use bitcoin::hashes::{Hash, HashEngine};
+use bitcoin::hashes::sha256::Hash as Sha256;
+use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1, SecretKey};
 
-use chain::keysinterface::{KeysInterface, Sign};
+use crate::chain::keysinterface::{KeysInterface, Recipient};
+use super::packet::ControlTlvs;
 use super::utils;
-use ln::msgs::DecodeError;
-use util::chacha20poly1305rfc::ChaChaPolyWriteAdapter;
-use util::ser::{Readable, VecWriter, Writeable, Writer};
+use crate::ln::msgs::DecodeError;
+use crate::ln::onion_utils;
+use crate::util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
+use crate::util::ser::{FixedLengthReader, LengthReadableArgs, Readable, VecWriter, Writeable, Writer};
 
-use io;
-use prelude::*;
+use core::mem;
+use core::ops::Deref;
+use crate::io::{self, Cursor};
+use crate::prelude::*;
 
 /// Onion messages can be sent and received to blinded routes, which serve to hide the identity of
 /// the recipient.
+#[derive(Clone, Debug, PartialEq)]
 pub struct BlindedRoute {
 	/// To send to a blinded route, the sender first finds a route to the unblinded
 	/// `introduction_node_id`, which can unblind its [`encrypted_payload`] to find out the onion
 	/// message's next hop and forward it along.
 	///
 	/// [`encrypted_payload`]: BlindedHop::encrypted_payload
-	pub(super) introduction_node_id: PublicKey,
+	pub(crate) introduction_node_id: PublicKey,
 	/// Used by the introduction node to decrypt its [`encrypted_payload`] to forward the onion
 	/// message.
 	///
 	/// [`encrypted_payload`]: BlindedHop::encrypted_payload
-	pub(super) blinding_point: PublicKey,
+	pub(crate) blinding_point: PublicKey,
 	/// The hops composing the blinded route.
-	pub(super) blinded_hops: Vec<BlindedHop>,
+	pub(crate) blinded_hops: Vec<BlindedHop>,
 }
 
 /// Used to construct the blinded hops portion of a blinded route. These hops cannot be identified
 /// by outside observers and thus can be used to hide the identity of the recipient.
+#[derive(Clone, Debug, PartialEq)]
 pub struct BlindedHop {
 	/// The blinded node id of this hop in a blinded route.
-	pub(super) blinded_node_id: PublicKey,
+	pub(crate) blinded_node_id: PublicKey,
 	/// The encrypted payload intended for this hop in a blinded route.
 	// The node sending to this blinded route will later encode this payload into the onion packet for
 	// this hop.
-	pub(super) encrypted_payload: Vec<u8>,
+	pub(crate) encrypted_payload: Vec<u8>,
 }
 
 impl BlindedRoute {
@@ -55,7 +63,7 @@ impl BlindedRoute {
 	///
 	/// Errors if less than two hops are provided or if `node_pk`(s) are invalid.
 	//  TODO: make all payloads the same size with padding + add dummy hops
-	pub fn new<Signer: Sign, K: KeysInterface, T: secp256k1::Signing + secp256k1::Verification>
+	pub fn new<K: KeysInterface, T: secp256k1::Signing + secp256k1::Verification>
 		(node_pks: &[PublicKey], keys_manager: &K, secp_ctx: &Secp256k1<T>) -> Result<Self, ()>
 	{
 		if node_pks.len() < 2 { return Err(()) }
@@ -69,6 +77,41 @@ impl BlindedRoute {
 			blinded_hops: blinded_hops(secp_ctx, node_pks, &blinding_secret).map_err(|_| ())?,
 		})
 	}
+
+	// Advance the blinded route by one hop, so make the second hop into the new introduction node.
+	pub(super) fn advance_by_one<K: Deref, T: secp256k1::Signing + secp256k1::Verification>
+		(&mut self, keys_manager: &K, secp_ctx: &Secp256k1<T>) -> Result<(), ()>
+		where K::Target: KeysInterface
+	{
+		let control_tlvs_ss = keys_manager.ecdh(Recipient::Node, &self.blinding_point, None)?;
+		let rho = onion_utils::gen_rho_from_shared_secret(&control_tlvs_ss.secret_bytes());
+		let encrypted_control_tlvs = self.blinded_hops.remove(0).encrypted_payload;
+		let mut s = Cursor::new(&encrypted_control_tlvs);
+		let mut reader = FixedLengthReader::new(&mut s, encrypted_control_tlvs.len() as u64);
+		match ChaChaPolyReadAdapter::read(&mut reader, rho) {
+			Ok(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(ForwardTlvs {
+				mut next_node_id, next_blinding_override,
+			})}) => {
+				let mut new_blinding_point = match next_blinding_override {
+					Some(blinding_point) => blinding_point,
+					None => {
+						let blinding_factor = {
+							let mut sha = Sha256::engine();
+							sha.input(&self.blinding_point.serialize()[..]);
+							sha.input(control_tlvs_ss.as_ref());
+							Sha256::from_engine(sha).into_inner()
+						};
+						self.blinding_point.mul_tweak(secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap())
+							.map_err(|_| ())?
+					}
+				};
+				mem::swap(&mut self.blinding_point, &mut new_blinding_point);
+				mem::swap(&mut self.introduction_node_id, &mut next_node_id);
+				Ok(())
+			},
+			_ => Err(())
+		}
+	}
 }
 
 /// Construct blinded hops for the given `unblinded_path`.