X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fblinded_path%2Fmod.rs;h=89087a10cd414ac9fdeae4331490ef97e73666ea;hb=bbe20c3327d3af37a7d5f82a021af1945d689547;hp=97d3a408cdb083603cbebca15fa40f0dda3dd1f0;hpb=6cb9919f0c84f61eb9281617ee3816c73e081747;p=rust-lightning diff --git a/lightning/src/blinded_path/mod.rs b/lightning/src/blinded_path/mod.rs index 97d3a408..89087a10 100644 --- a/lightning/src/blinded_path/mod.rs +++ b/lightning/src/blinded_path/mod.rs @@ -9,22 +9,17 @@ //! Creating blinded paths and related utilities live here. +pub mod payment; +pub(crate) mod message; pub(crate) mod utils; -use bitcoin::hashes::{Hash, HashEngine}; -use bitcoin::hashes::sha256::Hash as Sha256; -use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1, SecretKey}; +use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey}; -use crate::sign::{EntropySource, NodeSigner, Recipient}; -use crate::onion_message::ControlTlvs; +use crate::sign::EntropySource; use crate::ln::msgs::DecodeError; -use crate::ln::onion_utils; -use crate::util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter}; -use crate::util::ser::{FixedLengthReader, LengthReadableArgs, Readable, VecWriter, Writeable, Writer}; +use crate::util::ser::{Readable, Writeable, Writer}; -use core::mem; -use core::ops::Deref; -use crate::io::{self, Cursor}; +use crate::io; use crate::prelude::*; /// Onion messages and payments can be sent and received to blinded paths, which serve to hide the @@ -36,26 +31,27 @@ pub struct BlindedPath { /// message or payment's next hop and forward it along. /// /// [`encrypted_payload`]: BlindedHop::encrypted_payload - pub(crate) introduction_node_id: PublicKey, + 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(crate) blinding_point: PublicKey, + pub blinding_point: PublicKey, /// The hops composing the blinded path. - pub(crate) blinded_hops: Vec, + pub blinded_hops: Vec, } -/// Used to construct the blinded hops portion of a blinded path. These hops cannot be identified -/// by outside observers and thus can be used to hide the identity of the recipient. +/// 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 blinded path. - pub(crate) blinded_node_id: PublicKey, - /// The encrypted payload intended for this hop in a blinded path. + /// 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(crate) encrypted_payload: Vec, + pub encrypted_payload: Vec, } impl BlindedPath { @@ -75,87 +71,30 @@ impl BlindedPath { Ok(BlindedPath { introduction_node_id, blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret), - blinded_hops: blinded_message_hops(secp_ctx, node_pks, &blinding_secret).map_err(|_| ())?, + blinded_hops: message::blinded_hops(secp_ctx, node_pks, &blinding_secret).map_err(|_| ())?, }) } - // Advance the blinded onion message path by one hop, so make the second hop into the new - // introduction node. - pub(super) fn advance_message_path_by_one - (&mut self, node_signer: &NS, secp_ctx: &Secp256k1) -> Result<(), ()> - where NS::Target: NodeSigner - { - let control_tlvs_ss = node_signer.ecdh(Recipient::Node, &self.blinding_point, None)?; - let rho = onion_utils::gen_rho_from_shared_secret(&control_tlvs_ss.secret_bytes()); - let encrypted_control_tlvs = self.blinded_hops.remove(0).encrypted_payload; - let mut s = Cursor::new(&encrypted_control_tlvs); - let mut reader = FixedLengthReader::new(&mut s, encrypted_control_tlvs.len() as u64); - match ChaChaPolyReadAdapter::read(&mut reader, rho) { - Ok(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(ForwardTlvs { - mut next_node_id, next_blinding_override, - })}) => { - let mut new_blinding_point = match next_blinding_override { - Some(blinding_point) => blinding_point, - None => { - let blinding_factor = { - let mut sha = Sha256::engine(); - sha.input(&self.blinding_point.serialize()[..]); - sha.input(control_tlvs_ss.as_ref()); - Sha256::from_engine(sha).into_inner() - }; - self.blinding_point.mul_tweak(secp_ctx, &Scalar::from_be_bytes(blinding_factor).unwrap()) - .map_err(|_| ())? - } - }; - mem::swap(&mut self.blinding_point, &mut new_blinding_point); - mem::swap(&mut self.introduction_node_id, &mut next_node_id); - Ok(()) - }, - _ => Err(()) - } - } -} - -/// Construct blinded onion message hops for the given `unblinded_path`. -fn blinded_message_hops( - secp_ctx: &Secp256k1, unblinded_path: &[PublicKey], session_priv: &SecretKey -) -> Result, secp256k1::Error> { - let mut blinded_hops = Vec::with_capacity(unblinded_path.len()); - - let mut prev_ss_and_blinded_node_id = None; - utils::construct_keys_callback(secp_ctx, unblinded_path, None, session_priv, |blinded_node_id, _, _, encrypted_payload_ss, unblinded_pk, _| { - if let Some((prev_ss, prev_blinded_node_id)) = prev_ss_and_blinded_node_id { - if let Some(pk) = unblinded_pk { - let payload = ForwardTlvs { - next_node_id: pk, - next_blinding_override: None, - }; - blinded_hops.push(BlindedHop { - blinded_node_id: prev_blinded_node_id, - encrypted_payload: encrypt_payload(payload, prev_ss), - }); - } else { debug_assert!(false); } - } - prev_ss_and_blinded_node_id = Some((encrypted_payload_ss, blinded_node_id)); - })?; - - if let Some((final_ss, final_blinded_node_id)) = prev_ss_and_blinded_node_id { - let final_payload = ReceiveTlvs { path_id: None }; - blinded_hops.push(BlindedHop { - blinded_node_id: final_blinded_node_id, - encrypted_payload: encrypt_payload(final_payload, final_ss), - }); - } else { debug_assert!(false) } - - Ok(blinded_hops) -} + /// Create a blinded path for a payment, to be forwarded along `path`. The last node + /// in `path` will be the destination node. + /// + /// Errors if `path` is empty or a node id in `path` is invalid. + // TODO: make all payloads the same size with padding + add dummy hops + pub fn new_for_payment( + intermediate_nodes: &[(PublicKey, payment::ForwardTlvs)], payee_node_id: PublicKey, + payee_tlvs: payment::ReceiveTlvs, entropy_source: &ES, secp_ctx: &Secp256k1 + ) -> Result { + let blinding_secret_bytes = entropy_source.get_secure_random_bytes(); + let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted"); -/// Encrypt TLV payload to be used as a [`BlindedHop::encrypted_payload`]. -fn encrypt_payload(payload: P, encrypted_tlvs_ss: [u8; 32]) -> Vec { - let mut writer = VecWriter(Vec::new()); - let write_adapter = ChaChaPolyWriteAdapter::new(encrypted_tlvs_ss, &payload); - write_adapter.write(&mut writer).expect("In-memory writes cannot fail"); - writer.0 + Ok(BlindedPath { + introduction_node_id: intermediate_nodes.first().map_or(payee_node_id, |n| n.0), + 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 { @@ -193,41 +132,3 @@ impl_writeable!(BlindedHop, { encrypted_payload }); -/// TLVs to encode in an intermediate onion message packet's hop data. When provided in a blinded -/// route, they are encoded into [`BlindedHop::encrypted_payload`]. -pub(crate) struct ForwardTlvs { - /// The node id of the next hop in the onion message's path. - pub(super) next_node_id: PublicKey, - /// Senders to a blinded path use this value to concatenate the route they find to the - /// introduction node with the blinded path. - pub(super) next_blinding_override: Option, -} - -/// Similar to [`ForwardTlvs`], but these TLVs are for the final node. -pub(crate) struct ReceiveTlvs { - /// If `path_id` is `Some`, it is used to identify the blinded path that this onion message is - /// sending to. This is useful for receivers to check that said blinded path is being used in - /// the right context. - pub(super) path_id: Option<[u8; 32]>, -} - -impl Writeable for ForwardTlvs { - fn write(&self, writer: &mut W) -> Result<(), io::Error> { - // TODO: write padding - encode_tlv_stream!(writer, { - (4, self.next_node_id, required), - (8, self.next_blinding_override, option) - }); - Ok(()) - } -} - -impl Writeable for ReceiveTlvs { - fn write(&self, writer: &mut W) -> Result<(), io::Error> { - // TODO: write padding - encode_tlv_stream!(writer, { - (6, self.path_id, option), - }); - Ok(()) - } -}