/// LDK has multiple reasons to generate fake short channel ids:
/// 1) outbound SCID aliases we use for private channels
/// 2) phantom node payments, to get an scid for the phantom node's phantom channel
+/// 3) payments intended to be intercepted will route using a fake scid (this is typically used so
+/// the forwarding node can open a JIT channel to the next hop)
pub(crate) mod fake_scid {
use bitcoin::hash_types::BlockHash;
use bitcoin::hashes::hex::FromHex;
- use crate::chain::keysinterface::{Sign, KeysInterface};
+ use crate::chain::keysinterface::EntropySource;
use crate::util::chacha20::ChaCha20;
use crate::util::scid_utils;
pub(crate) enum Namespace {
Phantom,
OutboundAlias,
+ Intercept
}
impl Namespace {
/// between segwit activation and the current best known height, and the tx index and output
/// index are also selected from a "reasonable" range. We add this logic because it makes it
/// non-obvious at a glance that the scid is fake, e.g. if it appears in invoice route hints.
- pub(crate) fn get_fake_scid<Signer: Sign, K: Deref>(&self, highest_seen_blockheight: u32, genesis_hash: &BlockHash, fake_scid_rand_bytes: &[u8; 32], keys_manager: &K) -> u64
- where K::Target: KeysInterface<Signer = Signer>,
+ pub(crate) fn get_fake_scid<ES: Deref>(&self, highest_seen_blockheight: u32, genesis_hash: &BlockHash, fake_scid_rand_bytes: &[u8; 32], entropy_source: &ES) -> u64
+ where ES::Target: EntropySource,
{
// Ensure we haven't created a namespace that doesn't fit into the 3 bits we've allocated for
// namespaces.
assert!((*self as u8) < MAX_NAMESPACES);
- let rand_bytes = keys_manager.get_secure_random_bytes();
+ let rand_bytes = entropy_source.get_secure_random_bytes();
let segwit_activation_height = segwit_activation_height(genesis_hash);
let mut blocks_since_segwit_activation = highest_seen_blockheight.saturating_sub(segwit_activation_height);
}
}
- /// Returns whether the given fake scid falls into the given namespace.
+ /// Returns whether the given fake scid falls into the phantom namespace.
pub fn is_valid_phantom(fake_scid_rand_bytes: &[u8; 32], scid: u64, genesis_hash: &BlockHash) -> bool {
let block_height = scid_utils::block_from_scid(&scid);
let tx_index = scid_utils::tx_index_from_scid(&scid);
&& valid_vout == scid_utils::vout_from_scid(&scid) as u8
}
+ /// Returns whether the given fake scid falls into the intercept namespace.
+ pub fn is_valid_intercept(fake_scid_rand_bytes: &[u8; 32], scid: u64, genesis_hash: &BlockHash) -> bool {
+ let block_height = scid_utils::block_from_scid(&scid);
+ let tx_index = scid_utils::tx_index_from_scid(&scid);
+ let namespace = Namespace::Intercept;
+ let valid_vout = namespace.get_encrypted_vout(block_height, tx_index, fake_scid_rand_bytes);
+ block_height >= segwit_activation_height(genesis_hash)
+ && valid_vout == scid_utils::vout_from_scid(&scid) as u8
+ }
+
#[cfg(test)]
mod tests {
use bitcoin::blockdata::constants::genesis_block;
use bitcoin::network::constants::Network;
- use crate::util::scid_utils::fake_scid::{is_valid_phantom, MAINNET_SEGWIT_ACTIVATION_HEIGHT, MAX_TX_INDEX, MAX_NAMESPACES, Namespace, NAMESPACE_ID_BITMASK, segwit_activation_height, TEST_SEGWIT_ACTIVATION_HEIGHT};
+ use crate::util::scid_utils::fake_scid::{is_valid_intercept, is_valid_phantom, MAINNET_SEGWIT_ACTIVATION_HEIGHT, MAX_TX_INDEX, MAX_NAMESPACES, Namespace, NAMESPACE_ID_BITMASK, segwit_activation_height, TEST_SEGWIT_ACTIVATION_HEIGHT};
use crate::util::scid_utils;
use crate::util::test_utils;
use crate::sync::Arc;
let phantom_namespace = Namespace::Phantom;
assert!((phantom_namespace as u8) < MAX_NAMESPACES);
assert!((phantom_namespace as u8) <= NAMESPACE_ID_BITMASK);
+
+ let intercept_namespace = Namespace::Intercept;
+ assert!((intercept_namespace as u8) < MAX_NAMESPACES);
+ assert!((intercept_namespace as u8) <= NAMESPACE_ID_BITMASK);
}
#[test]
assert!(!is_valid_phantom(&fake_scid_rand_bytes, invalid_fake_scid, &testnet_genesis));
}
+ #[test]
+ fn test_is_valid_intercept() {
+ let namespace = Namespace::Intercept;
+ let fake_scid_rand_bytes = [0; 32];
+ let testnet_genesis = genesis_block(Network::Testnet).header.block_hash();
+ let valid_encrypted_vout = namespace.get_encrypted_vout(0, 0, &fake_scid_rand_bytes);
+ let valid_fake_scid = scid_utils::scid_from_parts(1, 0, valid_encrypted_vout as u64).unwrap();
+ assert!(is_valid_intercept(&fake_scid_rand_bytes, valid_fake_scid, &testnet_genesis));
+ let invalid_fake_scid = scid_utils::scid_from_parts(1, 0, 12).unwrap();
+ assert!(!is_valid_intercept(&fake_scid_rand_bytes, invalid_fake_scid, &testnet_genesis));
+ }
+
#[test]
fn test_get_fake_scid() {
let mainnet_genesis = genesis_block(Network::Bitcoin).header.block_hash();