1 // This file is Copyright its original authors, visible in version control
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
10 //! Creating blinded paths and related utilities live here.
13 pub(crate) mod message;
16 use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
18 use crate::ln::msgs::DecodeError;
19 use crate::offers::invoice::BlindedPayInfo;
20 use crate::routing::gossip::{NodeId, ReadOnlyNetworkGraph};
21 use crate::sign::EntropySource;
22 use crate::util::ser::{Readable, Writeable, Writer};
25 use crate::prelude::*;
27 /// Onion messages and payments can be sent and received to blinded paths, which serve to hide the
28 /// identity of the recipient.
29 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
30 pub struct BlindedPath {
31 /// To send to a blinded path, the sender first finds a route to the unblinded
32 /// `introduction_node`, which can unblind its [`encrypted_payload`] to find out the onion
33 /// message or payment's next hop and forward it along.
35 /// [`encrypted_payload`]: BlindedHop::encrypted_payload
36 pub introduction_node: IntroductionNode,
37 /// Used by the introduction node to decrypt its [`encrypted_payload`] to forward the onion
38 /// message or payment.
40 /// [`encrypted_payload`]: BlindedHop::encrypted_payload
41 pub blinding_point: PublicKey,
42 /// The hops composing the blinded path.
43 pub blinded_hops: Vec<BlindedHop>,
46 /// The unblinded node in a [`BlindedPath`].
47 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
48 pub enum IntroductionNode {
49 /// The node id of the introduction node.
51 /// The short channel id of the channel leading to the introduction node. The [`Direction`]
52 /// identifies which side of the channel is the introduction node.
53 DirectedShortChannelId(Direction, u64),
56 /// The side of a channel that is the [`IntroductionNode`] in a [`BlindedPath`]. [BOLT 7] defines
57 /// which nodes is which in the [`ChannelAnnouncement`] message.
59 /// [BOLT 7]: https://github.com/lightning/bolts/blob/master/07-routing-gossip.md#the-channel_announcement-message
60 /// [`ChannelAnnouncement`]: crate::ln::msgs::ChannelAnnouncement
61 #[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
63 /// The lesser node id when compared lexicographically in ascending order.
65 /// The greater node id when compared lexicographically in ascending order.
69 /// An interface for looking up the node id of a channel counterparty for the purpose of forwarding
70 /// an [`OnionMessage`].
72 /// [`OnionMessage`]: crate::ln::msgs::OnionMessage
73 pub trait NodeIdLookUp {
74 /// Returns the node id of the forwarding node's channel counterparty with `short_channel_id`.
76 /// Here, the forwarding node is referring to the node of the [`OnionMessenger`] parameterized
77 /// by the [`NodeIdLookUp`] and the counterparty to one of that node's peers.
79 /// [`OnionMessenger`]: crate::onion_message::messenger::OnionMessenger
80 fn next_node_id(&self, short_channel_id: u64) -> Option<PublicKey>;
83 /// A [`NodeIdLookUp`] that always returns `None`.
84 pub struct EmptyNodeIdLookUp {}
86 impl NodeIdLookUp for EmptyNodeIdLookUp {
87 fn next_node_id(&self, _short_channel_id: u64) -> Option<PublicKey> {
92 /// An encrypted payload and node id corresponding to a hop in a payment or onion message path, to
93 /// be encoded in the sender's onion packet. These hops cannot be identified by outside observers
94 /// and thus can be used to hide the identity of the recipient.
95 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
96 pub struct BlindedHop {
97 /// The blinded node id of this hop in a [`BlindedPath`].
98 pub blinded_node_id: PublicKey,
99 /// The encrypted payload intended for this hop in a [`BlindedPath`].
100 // The node sending to this blinded path will later encode this payload into the onion packet for
102 pub encrypted_payload: Vec<u8>,
106 /// Create a one-hop blinded path for a message.
107 pub fn one_hop_for_message<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
108 recipient_node_id: PublicKey, entropy_source: &ES, secp_ctx: &Secp256k1<T>
109 ) -> Result<Self, ()> {
110 Self::new_for_message(&[recipient_node_id], entropy_source, secp_ctx)
113 /// Create a blinded path for an onion message, to be forwarded along `node_pks`. The last node
114 /// pubkey in `node_pks` will be the destination node.
116 /// Errors if no hops are provided or if `node_pk`(s) are invalid.
117 // TODO: make all payloads the same size with padding + add dummy hops
118 pub fn new_for_message<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
119 node_pks: &[PublicKey], entropy_source: &ES, secp_ctx: &Secp256k1<T>
120 ) -> Result<Self, ()> {
121 if node_pks.is_empty() { return Err(()) }
122 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
123 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
124 let introduction_node = IntroductionNode::NodeId(node_pks[0]);
128 blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
129 blinded_hops: message::blinded_hops(secp_ctx, node_pks, &blinding_secret).map_err(|_| ())?,
133 /// Create a one-hop blinded path for a payment.
134 pub fn one_hop_for_payment<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
135 payee_node_id: PublicKey, payee_tlvs: payment::ReceiveTlvs, min_final_cltv_expiry_delta: u16,
136 entropy_source: &ES, secp_ctx: &Secp256k1<T>
137 ) -> Result<(BlindedPayInfo, Self), ()> {
138 // This value is not considered in pathfinding for 1-hop blinded paths, because it's intended to
139 // be in relation to a specific channel.
140 let htlc_maximum_msat = u64::max_value();
141 Self::new_for_payment(
142 &[], payee_node_id, payee_tlvs, htlc_maximum_msat, min_final_cltv_expiry_delta,
143 entropy_source, secp_ctx
147 /// Create a blinded path for a payment, to be forwarded along `intermediate_nodes`.
150 /// * a provided node id is invalid
151 /// * [`BlindedPayInfo`] calculation results in an integer overflow
152 /// * any unknown features are required in the provided [`ForwardTlvs`]
154 /// [`ForwardTlvs`]: crate::blinded_path::payment::ForwardTlvs
155 // TODO: make all payloads the same size with padding + add dummy hops
156 pub fn new_for_payment<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
157 intermediate_nodes: &[payment::ForwardNode], payee_node_id: PublicKey,
158 payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, min_final_cltv_expiry_delta: u16,
159 entropy_source: &ES, secp_ctx: &Secp256k1<T>
160 ) -> Result<(BlindedPayInfo, Self), ()> {
161 let introduction_node = IntroductionNode::NodeId(
162 intermediate_nodes.first().map_or(payee_node_id, |n| n.node_id)
164 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
165 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
167 let blinded_payinfo = payment::compute_payinfo(
168 intermediate_nodes, &payee_tlvs, htlc_maximum_msat, min_final_cltv_expiry_delta
170 Ok((blinded_payinfo, BlindedPath {
172 blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
173 blinded_hops: payment::blinded_hops(
174 secp_ctx, intermediate_nodes, payee_node_id, payee_tlvs, &blinding_secret
179 /// Returns the introduction [`NodeId`] of the blinded path, if it is publicly reachable (i.e.,
180 /// it is found in the network graph).
181 pub fn public_introduction_node_id<'a>(
182 &self, network_graph: &'a ReadOnlyNetworkGraph
183 ) -> Option<&'a NodeId> {
184 match &self.introduction_node {
185 IntroductionNode::NodeId(pubkey) => {
186 let node_id = NodeId::from_pubkey(pubkey);
187 network_graph.nodes().get_key_value(&node_id).map(|(key, _)| key)
189 IntroductionNode::DirectedShortChannelId(direction, scid) => {
192 .map(|c| match direction {
193 Direction::NodeOne => &c.node_one,
194 Direction::NodeTwo => &c.node_two,
201 impl Writeable for BlindedPath {
202 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
203 match &self.introduction_node {
204 IntroductionNode::NodeId(pubkey) => pubkey.write(w)?,
205 IntroductionNode::DirectedShortChannelId(direction, scid) => {
207 Direction::NodeOne => 0u8.write(w)?,
208 Direction::NodeTwo => 1u8.write(w)?,
214 self.blinding_point.write(w)?;
215 (self.blinded_hops.len() as u8).write(w)?;
216 for hop in &self.blinded_hops {
223 impl Readable for BlindedPath {
224 fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
225 let mut first_byte: u8 = Readable::read(r)?;
226 let introduction_node = match first_byte {
227 0 => IntroductionNode::DirectedShortChannelId(Direction::NodeOne, Readable::read(r)?),
228 1 => IntroductionNode::DirectedShortChannelId(Direction::NodeTwo, Readable::read(r)?),
231 let mut pubkey_read = core::slice::from_mut(&mut first_byte).chain(r.by_ref());
232 IntroductionNode::NodeId(Readable::read(&mut pubkey_read)?)
234 _ => return Err(DecodeError::InvalidValue),
236 let blinding_point = Readable::read(r)?;
237 let num_hops: u8 = Readable::read(r)?;
238 if num_hops == 0 { return Err(DecodeError::InvalidValue) }
239 let mut blinded_hops: Vec<BlindedHop> = Vec::with_capacity(num_hops.into());
240 for _ in 0..num_hops {
241 blinded_hops.push(Readable::read(r)?);
251 impl_writeable!(BlindedHop, {
257 /// Returns the [`NodeId`] from the inputs corresponding to the direction.
258 pub fn select_node_id<'a>(&self, node_a: &'a NodeId, node_b: &'a NodeId) -> &'a NodeId {
260 Direction::NodeOne => core::cmp::min(node_a, node_b),
261 Direction::NodeTwo => core::cmp::max(node_a, node_b),
265 /// Returns the [`PublicKey`] from the inputs corresponding to the direction.
266 pub fn select_pubkey<'a>(&self, node_a: &'a PublicKey, node_b: &'a PublicKey) -> &'a PublicKey {
267 let (node_one, node_two) = if NodeId::from_pubkey(node_a) < NodeId::from_pubkey(node_b) {
273 Direction::NodeOne => node_one,
274 Direction::NodeTwo => node_two,