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.
12 pub(crate) mod message;
15 use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
17 use crate::sign::{EntropySource, NodeSigner, Recipient};
18 use crate::onion_message::ControlTlvs;
19 use crate::ln::msgs::DecodeError;
20 use crate::ln::onion_utils;
21 use crate::util::chacha20poly1305rfc::ChaChaPolyReadAdapter;
22 use crate::util::ser::{FixedLengthReader, LengthReadableArgs, Readable, Writeable, Writer};
26 use crate::io::{self, Cursor};
27 use crate::prelude::*;
29 /// Onion messages and payments can be sent and received to blinded paths, which serve to hide the
30 /// identity of the recipient.
31 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
32 pub struct BlindedPath {
33 /// To send to a blinded path, the sender first finds a route to the unblinded
34 /// `introduction_node_id`, which can unblind its [`encrypted_payload`] to find out the onion
35 /// message or payment's next hop and forward it along.
37 /// [`encrypted_payload`]: BlindedHop::encrypted_payload
38 pub introduction_node_id: PublicKey,
39 /// Used by the introduction node to decrypt its [`encrypted_payload`] to forward the onion
40 /// message or payment.
42 /// [`encrypted_payload`]: BlindedHop::encrypted_payload
43 pub blinding_point: PublicKey,
44 /// The hops composing the blinded path.
45 pub blinded_hops: Vec<BlindedHop>,
48 /// Used to construct the blinded hops portion of a blinded path. These hops cannot be identified
49 /// by outside observers and thus can be used to hide the identity of the recipient.
50 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
51 pub struct BlindedHop {
52 /// The blinded node id of this hop in a blinded path.
53 pub blinded_node_id: PublicKey,
54 /// The encrypted payload intended for this hop in a blinded path.
55 // The node sending to this blinded path will later encode this payload into the onion packet for
57 pub encrypted_payload: Vec<u8>,
61 /// Create a blinded path for an onion message, to be forwarded along `node_pks`. The last node
62 /// pubkey in `node_pks` will be the destination node.
64 /// Errors if less than two hops are provided or if `node_pk`(s) are invalid.
65 // TODO: make all payloads the same size with padding + add dummy hops
66 pub fn new_for_message<ES: EntropySource, T: secp256k1::Signing + secp256k1::Verification>
67 (node_pks: &[PublicKey], entropy_source: &ES, secp_ctx: &Secp256k1<T>) -> Result<Self, ()>
69 if node_pks.len() < 2 { return Err(()) }
70 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
71 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
72 let introduction_node_id = node_pks[0];
76 blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
77 blinded_hops: message::blinded_hops(secp_ctx, node_pks, &blinding_secret).map_err(|_| ())?,
81 // Advance the blinded onion message path by one hop, so make the second hop into the new
83 pub(super) fn advance_message_path_by_one<NS: Deref, T: secp256k1::Signing + secp256k1::Verification>
84 (&mut self, node_signer: &NS, secp_ctx: &Secp256k1<T>) -> Result<(), ()>
85 where NS::Target: NodeSigner
87 let control_tlvs_ss = node_signer.ecdh(Recipient::Node, &self.blinding_point, None)?;
88 let rho = onion_utils::gen_rho_from_shared_secret(&control_tlvs_ss.secret_bytes());
89 let encrypted_control_tlvs = self.blinded_hops.remove(0).encrypted_payload;
90 let mut s = Cursor::new(&encrypted_control_tlvs);
91 let mut reader = FixedLengthReader::new(&mut s, encrypted_control_tlvs.len() as u64);
92 match ChaChaPolyReadAdapter::read(&mut reader, rho) {
93 Ok(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(message::ForwardTlvs {
94 mut next_node_id, next_blinding_override,
96 let mut new_blinding_point = match next_blinding_override {
97 Some(blinding_point) => blinding_point,
99 onion_utils::next_hop_pubkey(secp_ctx, self.blinding_point,
100 control_tlvs_ss.as_ref()).map_err(|_| ())?
103 mem::swap(&mut self.blinding_point, &mut new_blinding_point);
104 mem::swap(&mut self.introduction_node_id, &mut next_node_id);
112 impl Writeable for BlindedPath {
113 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
114 self.introduction_node_id.write(w)?;
115 self.blinding_point.write(w)?;
116 (self.blinded_hops.len() as u8).write(w)?;
117 for hop in &self.blinded_hops {
124 impl Readable for BlindedPath {
125 fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
126 let introduction_node_id = Readable::read(r)?;
127 let blinding_point = Readable::read(r)?;
128 let num_hops: u8 = Readable::read(r)?;
129 if num_hops == 0 { return Err(DecodeError::InvalidValue) }
130 let mut blinded_hops: Vec<BlindedHop> = Vec::with_capacity(num_hops.into());
131 for _ in 0..num_hops {
132 blinded_hops.push(Readable::read(r)?);
135 introduction_node_id,
142 impl_writeable!(BlindedHop, {