_ Git - rust-lightning/blob - lightning/src/blinded_path/mod.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   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
   8 // licenses.
   9
  10 //! Creating blinded paths and related utilities live here.
  11
  12 pub mod payment;
  13 pub(crate) mod message;
  14 pub(crate) mod utils;
  15
  16 use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
  17
  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};
  23
  24 use crate::io;
  25 use crate::prelude::*;
  26
  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.
  34         ///
  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.
  39         ///
  40         /// [`encrypted_payload`]: BlindedHop::encrypted_payload
  41         pub blinding_point: PublicKey,
  42         /// The hops composing the blinded path.
  43         pub blinded_hops: Vec<BlindedHop>,
  44 }
  45
  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.
  50         NodeId(PublicKey),
  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),
  54 }
  55
  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.
  58 ///
  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, Debug, Hash, PartialEq, Eq)]
  62 pub enum Direction {
  63         /// The lesser node id when compared lexicographically in ascending order.
  64         NodeOne,
  65         /// The greater node id when compared lexicographically in ascending order.
  66         NodeTwo,
  67 }
  68
  69 /// An encrypted payload and node id corresponding to a hop in a payment or onion message path, to
  70 /// be encoded in the sender's onion packet. These hops cannot be identified by outside observers
  71 /// and thus can be used to hide the identity of the recipient.
  72 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
  73 pub struct BlindedHop {
  74         /// The blinded node id of this hop in a [`BlindedPath`].
  75         pub blinded_node_id: PublicKey,
  76         /// The encrypted payload intended for this hop in a [`BlindedPath`].
  77         // The node sending to this blinded path will later encode this payload into the onion packet for
  78         // this hop.
  79         pub encrypted_payload: Vec<u8>,
  80 }
  81
  82 impl BlindedPath {
  83         /// Create a one-hop blinded path for a message.
  84         pub fn one_hop_for_message<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
  85                 recipient_node_id: PublicKey, entropy_source: &ES, secp_ctx: &Secp256k1<T>
  86         ) -> Result<Self, ()> {
  87                 Self::new_for_message(&[recipient_node_id], entropy_source, secp_ctx)
  88         }
  89
  90         /// Create a blinded path for an onion message, to be forwarded along `node_pks`. The last node
  91         /// pubkey in `node_pks` will be the destination node.
  92         ///
  93         /// Errors if no hops are provided or if `node_pk`(s) are invalid.
  94         //  TODO: make all payloads the same size with padding + add dummy hops
  95         pub fn new_for_message<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
  96                 node_pks: &[PublicKey], entropy_source: &ES, secp_ctx: &Secp256k1<T>
  97         ) -> Result<Self, ()> {
  98                 if node_pks.is_empty() { return Err(()) }
  99                 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 100                 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 101                 let introduction_node = IntroductionNode::NodeId(node_pks[0]);
 102
 103                 Ok(BlindedPath {
 104                         introduction_node,
 105                         blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
 106                         blinded_hops: message::blinded_hops(secp_ctx, node_pks, &blinding_secret).map_err(|_| ())?,
 107                 })
 108         }
 109
 110         /// Create a one-hop blinded path for a payment.
 111         pub fn one_hop_for_payment<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
 112                 payee_node_id: PublicKey, payee_tlvs: payment::ReceiveTlvs, min_final_cltv_expiry_delta: u16,
 113                 entropy_source: &ES, secp_ctx: &Secp256k1<T>
 114         ) -> Result<(BlindedPayInfo, Self), ()> {
 115                 // This value is not considered in pathfinding for 1-hop blinded paths, because it's intended to
 116                 // be in relation to a specific channel.
 117                 let htlc_maximum_msat = u64::max_value();
 118                 Self::new_for_payment(
 119                         &[], payee_node_id, payee_tlvs, htlc_maximum_msat, min_final_cltv_expiry_delta,
 120                         entropy_source, secp_ctx
 121                 )
 122         }
 123
 124         /// Create a blinded path for a payment, to be forwarded along `intermediate_nodes`.
 125         ///
 126         /// Errors if:
 127         /// * a provided node id is invalid
 128         /// * [`BlindedPayInfo`] calculation results in an integer overflow
 129         /// * any unknown features are required in the provided [`ForwardTlvs`]
 130         ///
 131         /// [`ForwardTlvs`]: crate::blinded_path::payment::ForwardTlvs
 132         //  TODO: make all payloads the same size with padding + add dummy hops
 133         pub fn new_for_payment<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
 134                 intermediate_nodes: &[payment::ForwardNode], payee_node_id: PublicKey,
 135                 payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, min_final_cltv_expiry_delta: u16,
 136                 entropy_source: &ES, secp_ctx: &Secp256k1<T>
 137         ) -> Result<(BlindedPayInfo, Self), ()> {
 138                 let introduction_node = IntroductionNode::NodeId(
 139                         intermediate_nodes.first().map_or(payee_node_id, |n| n.node_id)
 140                 );
 141                 let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 142                 let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 143
 144                 let blinded_payinfo = payment::compute_payinfo(
 145                         intermediate_nodes, &payee_tlvs, htlc_maximum_msat, min_final_cltv_expiry_delta
 146                 )?;
 147                 Ok((blinded_payinfo, BlindedPath {
 148                         introduction_node,
 149                         blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
 150                         blinded_hops: payment::blinded_hops(
 151                                 secp_ctx, intermediate_nodes, payee_node_id, payee_tlvs, &blinding_secret
 152                         ).map_err(|_| ())?,
 153                 }))
 154         }
 155
 156         /// Returns the introduction [`NodeId`] of the blinded path, if it is publicly reachable (i.e.,
 157         /// it is found in the network graph).
 158         pub fn public_introduction_node_id<'a>(
 159                 &self, network_graph: &'a ReadOnlyNetworkGraph
 160         ) -> Option<&'a NodeId> {
 161                 match &self.introduction_node {
 162                         IntroductionNode::NodeId(pubkey) => {
 163                                 let node_id = NodeId::from_pubkey(pubkey);
 164                                 network_graph.nodes().get_key_value(&node_id).map(|(key, _)| key)
 165                         },
 166                         IntroductionNode::DirectedShortChannelId(direction, scid) => {
 167                                 network_graph
 168                                         .channel(*scid)
 169                                         .map(|c| match direction {
 170                                                 Direction::NodeOne => &c.node_one,
 171                                                 Direction::NodeTwo => &c.node_two,
 172                                         })
 173                         },
 174                 }
 175         }
 176 }
 177
 178 impl Writeable for BlindedPath {
 179         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 180                 match &self.introduction_node {
 181                         IntroductionNode::NodeId(pubkey) => pubkey.write(w)?,
 182                         IntroductionNode::DirectedShortChannelId(direction, scid) => {
 183                                 match direction {
 184                                         Direction::NodeOne => 0u8.write(w)?,
 185                                         Direction::NodeTwo => 1u8.write(w)?,
 186                                 }
 187                                 scid.write(w)?;
 188                         },
 189                 }
 190
 191                 self.blinding_point.write(w)?;
 192                 (self.blinded_hops.len() as u8).write(w)?;
 193                 for hop in &self.blinded_hops {
 194                         hop.write(w)?;
 195                 }
 196                 Ok(())
 197         }
 198 }
 199
 200 impl Readable for BlindedPath {
 201         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 202                 let mut first_byte: u8 = Readable::read(r)?;
 203                 let introduction_node = match first_byte {
 204                         0 => IntroductionNode::DirectedShortChannelId(Direction::NodeOne, Readable::read(r)?),
 205                         1 => IntroductionNode::DirectedShortChannelId(Direction::NodeTwo, Readable::read(r)?),
 206                         2|3 => {
 207                                 use io::Read;
 208                                 let mut pubkey_read = core::slice::from_mut(&mut first_byte).chain(r.by_ref());
 209                                 IntroductionNode::NodeId(Readable::read(&mut pubkey_read)?)
 210                         },
 211                         _ => return Err(DecodeError::InvalidValue),
 212                 };
 213                 let blinding_point = Readable::read(r)?;
 214                 let num_hops: u8 = Readable::read(r)?;
 215                 if num_hops == 0 { return Err(DecodeError::InvalidValue) }
 216                 let mut blinded_hops: Vec<BlindedHop> = Vec::with_capacity(num_hops.into());
 217                 for _ in 0..num_hops {
 218                         blinded_hops.push(Readable::read(r)?);
 219                 }
 220                 Ok(BlindedPath {
 221                         introduction_node,
 222                         blinding_point,
 223                         blinded_hops,
 224                 })
 225         }
 226 }
 227
 228 impl_writeable!(BlindedHop, {
 229         blinded_node_id,
 230         encrypted_payload
 231 });
 232
 233 impl Direction {
 234         /// Returns the [`NodeId`] from the inputs corresponding to the direction.
 235         pub fn select_node_id<'a>(&self, node_a: &'a NodeId, node_b: &'a NodeId) -> &'a NodeId {
 236                 match self {
 237                         Direction::NodeOne => core::cmp::min(node_a, node_b),
 238                         Direction::NodeTwo => core::cmp::max(node_a, node_b),
 239                 }
 240         }
 241 }