Add V2 constructors to ChannelId

Author: dunxen

lightning/src/ln/channel_id.rs

@@ -14,8 +14,10 @@ use crate::io;
 use crate::ln::msgs::DecodeError;
 use crate::sign::EntropySource;
 use crate::util::ser::{Readable, Writeable, Writer};
+use super::channel_keys::RevocationBasepoint;
 
 use bitcoin::hashes::Hash as _;
+use bitcoin::hashes::sha256::Hash as Sha256;
 use core::fmt;
 use core::ops::Deref;
 
@@ -68,6 +70,28 @@ impl ChannelId {
 	pub fn is_zero(&self) -> bool {
 		self.0[..] == [0; 32]
 	}
+
+	/// Create _v2_ channel ID by concatenating the holder revocation basepoint with the counterparty
+	/// revocation basepoint and hashing the result. The basepoints will be concatenated in increasing
+	/// sorted order.
+	pub fn v2_from_revocation_basepoints(
+		ours: &RevocationBasepoint,
+		theirs: &RevocationBasepoint,
+	) -> Self {
+		let (lesser_point, greater_point) = if *ours < *theirs {
+			(ours, theirs)
+		} else {
+			(theirs, ours)
+		};
+
+		Self(Sha256::hash(&[lesser_point.0.serialize(), greater_point.0.serialize()].concat()).to_byte_array())
+	}
+
+	/// Create temporary _v2_ channel ID by concatenating a zeroed out basepoint with the holder
+	/// revocation basepoint and hashing the result.
+	pub fn temporary_v2_from_revocation_basepoint(our_revocation_basepoint: &RevocationBasepoint) -> Self {
+		Self(Sha256::hash(&[[0u8; 33], our_revocation_basepoint.0.serialize()].concat()).to_byte_array())
+	}
 }
 
 impl Writeable for ChannelId {

lightning/src/ln/channel_keys.rs

@@ -164,7 +164,7 @@ fn derive_public_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitm
 
 /// Master key used in conjunction with per_commitment_point to generate [htlcpubkey](https://github.com/lightning/bolts/blob/master/03-transactions.md#key-derivation) for the latest state of a channel.
 /// A watcher can be given a [RevocationBasepoint] to generate per commitment [RevocationKey] to create justice transactions.
-#[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
+#[derive(PartialEq, PartialOrd, Eq, Clone, Copy, Debug, Hash)]
 pub struct RevocationBasepoint(pub PublicKey);
 basepoint_impl!(RevocationBasepoint);
 key_read_write!(RevocationBasepoint);