// This file is Copyright its original authors, visible in version control // history. // // This file is licensed under the Apache License, Version 2.0 or the MIT license // , at your option. // You may not use this file except in accordance with one or both of these // licenses. //! Creating blinded paths and related utilities live here. pub mod payment; pub(crate) mod message; pub(crate) mod utils; use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey}; use crate::ln::msgs::DecodeError; use crate::offers::invoice::BlindedPayInfo; use crate::sign::EntropySource; use crate::util::ser::{Readable, Writeable, Writer}; use crate::io; use crate::prelude::*; /// Onion messages and payments can be sent and received to blinded paths, which serve to hide the /// identity of the recipient. #[derive(Clone, Debug, Hash, PartialEq, Eq)] pub struct BlindedPath { /// To send to a blinded path, the sender first finds a route to the unblinded /// `introduction_node_id`, which can unblind its [`encrypted_payload`] to find out the onion /// message or payment's next hop and forward it along. /// /// [`encrypted_payload`]: BlindedHop::encrypted_payload pub introduction_node_id: PublicKey, /// Used by the introduction node to decrypt its [`encrypted_payload`] to forward the onion /// message or payment. /// /// [`encrypted_payload`]: BlindedHop::encrypted_payload pub blinding_point: PublicKey, /// The hops composing the blinded path. pub blinded_hops: Vec, } /// An encrypted payload and node id corresponding to a hop in a payment or onion message path, to /// be encoded in the sender's onion packet. These hops cannot be identified by outside observers /// and thus can be used to hide the identity of the recipient. #[derive(Clone, Debug, Hash, PartialEq, Eq)] pub struct BlindedHop { /// The blinded node id of this hop in a [`BlindedPath`]. pub blinded_node_id: PublicKey, /// The encrypted payload intended for this hop in a [`BlindedPath`]. // The node sending to this blinded path will later encode this payload into the onion packet for // this hop. pub encrypted_payload: Vec, } impl BlindedPath { /// Create a one-hop blinded path for a message. pub fn one_hop_for_message( recipient_node_id: PublicKey, entropy_source: &ES, secp_ctx: &Secp256k1 ) -> Result { Self::new_for_message(&[recipient_node_id], entropy_source, secp_ctx) } /// Create a blinded path for an onion message, to be forwarded along `node_pks`. The last node /// pubkey in `node_pks` will be the destination node. /// /// Errors if no 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_for_message( node_pks: &[PublicKey], entropy_source: &ES, secp_ctx: &Secp256k1 ) -> Result { if node_pks.is_empty() { return Err(()) } let blinding_secret_bytes = entropy_source.get_secure_random_bytes(); let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted"); let introduction_node_id = node_pks[0]; Ok(BlindedPath { introduction_node_id, blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret), blinded_hops: message::blinded_hops(secp_ctx, node_pks, &blinding_secret).map_err(|_| ())?, }) } /// Create a one-hop blinded path for a payment. pub fn one_hop_for_payment( payee_node_id: PublicKey, payee_tlvs: payment::ReceiveTlvs, entropy_source: &ES, secp_ctx: &Secp256k1 ) -> Result<(BlindedPayInfo, Self), ()> { // This value is not considered in pathfinding for 1-hop blinded paths, because it's intended to // be in relation to a specific channel. let htlc_maximum_msat = u64::max_value(); Self::new_for_payment( &[], payee_node_id, payee_tlvs, htlc_maximum_msat, entropy_source, secp_ctx ) } /// Create a blinded path for a payment, to be forwarded along `intermediate_nodes`. /// /// Errors if: /// * a provided node id is invalid /// * [`BlindedPayInfo`] calculation results in an integer overflow /// * any unknown features are required in the provided [`ForwardTlvs`] /// /// [`ForwardTlvs`]: crate::blinded_path::payment::ForwardTlvs // TODO: make all payloads the same size with padding + add dummy hops pub(crate) fn new_for_payment( intermediate_nodes: &[payment::ForwardNode], payee_node_id: PublicKey, payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, entropy_source: &ES, secp_ctx: &Secp256k1 ) -> Result<(BlindedPayInfo, Self), ()> { let blinding_secret_bytes = entropy_source.get_secure_random_bytes(); let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted"); let blinded_payinfo = payment::compute_payinfo(intermediate_nodes, &payee_tlvs, htlc_maximum_msat)?; Ok((blinded_payinfo, BlindedPath { introduction_node_id: intermediate_nodes.first().map_or(payee_node_id, |n| n.node_id), blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret), blinded_hops: payment::blinded_hops( secp_ctx, intermediate_nodes, payee_node_id, payee_tlvs, &blinding_secret ).map_err(|_| ())?, })) } } impl Writeable for BlindedPath { fn write(&self, w: &mut W) -> Result<(), io::Error> { self.introduction_node_id.write(w)?; self.blinding_point.write(w)?; (self.blinded_hops.len() as u8).write(w)?; for hop in &self.blinded_hops { hop.write(w)?; } Ok(()) } } impl Readable for BlindedPath { fn read(r: &mut R) -> Result { let introduction_node_id = Readable::read(r)?; let blinding_point = Readable::read(r)?; let num_hops: u8 = Readable::read(r)?; if num_hops == 0 { return Err(DecodeError::InvalidValue) } let mut blinded_hops: Vec = Vec::with_capacity(num_hops.into()); for _ in 0..num_hops { blinded_hops.push(Readable::read(r)?); } Ok(BlindedPath { introduction_node_id, blinding_point, blinded_hops, }) } } impl_writeable!(BlindedHop, { blinded_node_id, encrypted_payload });