Merge pull request #165 from LNP-BP/v0.11

Add proof match operation

commit_verify/src/mpc/block.rs

@@ -170,7 +170,9 @@ impl StrictDumb for MerkleBlock {
 impl StrictSerialize for MerkleBlock {}
 impl StrictDeserialize for MerkleBlock {}
 
-impl Proof for MerkleBlock {}
+impl Proof for MerkleBlock {
+    fn matches(&self, other: &Self) -> bool { self.commit_id() == other.commit_id() }
+}
 
 impl From<&MerkleTree> for MerkleBlock {
     fn from(tree: &MerkleTree) -> Self {
@@ -621,7 +623,11 @@ pub struct MerkleProof {
     path: Confined<Vec<MerkleHash>, 0, 32>,
 }
 
-impl Proof for MerkleProof {}
+impl Proof for MerkleProof {
+    fn matches(&self, other: &Self) -> bool {
+        self.cofactor == other.cofactor && self.merkle_root() == other.merkle_root()
+    }
+}
 
 impl MerkleProof {
     /// Computes the depth of the merkle tree.
@@ -639,6 +645,11 @@ impl MerkleProof {
     /// Returns inner merkle path representation
     pub fn as_path(&self) -> &[MerkleHash] { &self.path }
 
+    /// Returns the root of the merkle path.
+    ///
+    /// If the MPC proof contains only a single message returns None
+    pub fn merkle_root(&self) -> Option<MerkleHash> { self.path.get(0).copied() }
+
     /// Convolves the proof with the `message` under the given `protocol_id`,
     /// producing [`Commitment`].
     pub fn convolve(

commit_verify/src/mpc/mod.rs

@@ -38,4 +38,10 @@ pub use tree::{Error, MerkleTree};
 pub trait Proof:
     strict_encoding::StrictEncode + strict_encoding::StrictDecode + Eq + std::fmt::Debug
 {
+    /// Verifies whether one MPC proof matches another MPC proof.
+    ///
+    /// This is not the same as `Eq`, since two proofs may reveal different
+    /// messages, and be non-equivalent, at the same time matching each other,
+    /// i.e. having the same merkle root and producing the same commitments.
+    fn matches(&self, other: &Self) -> bool;
 }

commit_verify/src/mpc/tree.rs

@@ -27,7 +27,7 @@ pub use self::commit::Error;
 use crate::merkle::MerkleHash;
 use crate::mpc::atoms::Leaf;
 use crate::mpc::{Commitment, MerkleBlock, Message, MessageMap, Proof, ProtocolId};
-use crate::{Conceal, LIB_NAME_COMMIT_VERIFY};
+use crate::{CommitId, Conceal, LIB_NAME_COMMIT_VERIFY};
 
 /// Number of cofactor variants tried before moving to the next tree depth.
 #[allow(dead_code)]
@@ -58,7 +58,9 @@ pub struct MerkleTree {
     pub(super) map: OrderedMap,
 }
 
-impl Proof for MerkleTree {}
+impl Proof for MerkleTree {
+    fn matches(&self, other: &Self) -> bool { self.commit_id() == other.commit_id() }
+}
 
 impl MerkleTree {
     pub fn root(&self) -> MerkleHash {