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::sign::EntropySource;
21 use crate::util::ser::{Readable, Writeable, Writer};
24 use crate::prelude::*;
26 /// Onion messages and payments can be sent and received to blinded paths, which serve to hide the
27 /// identity of the recipient.
28 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
29 pub struct BlindedPath {
30 /// To send to a blinded path, the sender first finds a route to the unblinded
31 /// `introduction_node_id`, which can unblind its [`encrypted_payload`] to find out the onion
32 /// message or payment's next hop and forward it along.
34 /// [`encrypted_payload`]: BlindedHop::encrypted_payload
35 pub introduction_node_id: PublicKey,
36 /// Used by the introduction node to decrypt its [`encrypted_payload`] to forward the onion
37 /// message or payment.
39 /// [`encrypted_payload`]: BlindedHop::encrypted_payload
40 pub blinding_point: PublicKey,
41 /// The hops composing the blinded path.
42 pub blinded_hops: Vec<BlindedHop>,
45 /// An encrypted payload and node id corresponding to a hop in a payment or onion message path, to
46 /// be encoded in the sender's onion packet. These hops cannot be identified by outside observers
47 /// and thus can be used to hide the identity of the recipient.
48 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
49 pub struct BlindedHop {
50 /// The blinded node id of this hop in a [`BlindedPath`].
51 pub blinded_node_id: PublicKey,
52 /// The encrypted payload intended for this hop in a [`BlindedPath`].
53 // The node sending to this blinded path will later encode this payload into the onion packet for
55 pub encrypted_payload: Vec<u8>,
59 /// Create a blinded path for an onion message, to be forwarded along `node_pks`. The last node
60 /// pubkey in `node_pks` will be the destination node.
62 /// Errors if less than two hops are provided or if `node_pk`(s) are invalid.
63 // TODO: make all payloads the same size with padding + add dummy hops
64 pub fn new_for_message<ES: EntropySource, T: secp256k1::Signing + secp256k1::Verification>
65 (node_pks: &[PublicKey], entropy_source: &ES, secp_ctx: &Secp256k1<T>) -> Result<Self, ()>
67 if node_pks.len() < 2 { return Err(()) }
68 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
69 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
70 let introduction_node_id = node_pks[0];
74 blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
75 blinded_hops: message::blinded_hops(secp_ctx, node_pks, &blinding_secret).map_err(|_| ())?,
79 /// Create a blinded path for a payment, to be forwarded along `intermediate_nodes`.
82 /// * a provided node id is invalid
83 /// * [`BlindedPayInfo`] calculation results in an integer overflow
84 /// * any unknown features are required in the provided [`ForwardTlvs`]
86 /// [`ForwardTlvs`]: crate::blinded_path::payment::ForwardTlvs
87 // TODO: make all payloads the same size with padding + add dummy hops
88 pub fn new_for_payment<ES: EntropySource, T: secp256k1::Signing + secp256k1::Verification>(
89 intermediate_nodes: &[payment::ForwardNode], payee_node_id: PublicKey,
90 payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, entropy_source: &ES,
91 secp_ctx: &Secp256k1<T>
92 ) -> Result<(BlindedPayInfo, Self), ()> {
93 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
94 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
96 let blinded_payinfo = payment::compute_payinfo(intermediate_nodes, &payee_tlvs, htlc_maximum_msat)?;
97 Ok((blinded_payinfo, BlindedPath {
98 introduction_node_id: intermediate_nodes.first().map_or(payee_node_id, |n| n.node_id),
99 blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
100 blinded_hops: payment::blinded_hops(
101 secp_ctx, intermediate_nodes, payee_node_id, payee_tlvs, &blinding_secret
107 impl Writeable for BlindedPath {
108 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
109 self.introduction_node_id.write(w)?;
110 self.blinding_point.write(w)?;
111 (self.blinded_hops.len() as u8).write(w)?;
112 for hop in &self.blinded_hops {
119 impl Readable for BlindedPath {
120 fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
121 let introduction_node_id = Readable::read(r)?;
122 let blinding_point = Readable::read(r)?;
123 let num_hops: u8 = Readable::read(r)?;
124 if num_hops == 0 { return Err(DecodeError::InvalidValue) }
125 let mut blinded_hops: Vec<BlindedHop> = Vec::with_capacity(num_hops.into());
126 for _ in 0..num_hops {
127 blinded_hops.push(Readable::read(r)?);
130 introduction_node_id,
137 impl_writeable!(BlindedHop, {