add method to validate a merkle tree inclusion proof (for indy-vdr)

Signed-off-by: Andrew Whitehead <[email protected]>
hyperledger · Aug 2, 2023 · 16b0ca4 · 16b0ca4
1 parent dfe94c6
commit 16b0ca4
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Showing 2 changed files with 46 additions and 3 deletions.
diff --git a/indy-data-types/src/merkle_tree/mod.rs b/indy-data-types/src/merkle_tree/mod.rs
@@ -3,9 +3,10 @@ use indy_utils::hash::{TreeHash, SHA256::DigestType as Hash};
 use self::tree::{Tree, TreeLeafData};
 use crate::ValidationError;
 
-mod merkletree;
 pub use self::merkletree::MerkleTree;
+pub use self::proof::Positioned;
 
+mod merkletree;
 mod proof;
 mod tree;
 
@@ -199,6 +200,25 @@ impl MerkleTree {
         }
         Ok(())
     }
+
+    pub fn check_inclusion_proof(
+        root_hash: &[u8],
+        leaf_value: &TreeLeafData,
+        path: &[Positioned<TreeLeafData>],
+    ) -> Result<bool, ValidationError> {
+        let mut check_hash = Hash::hash_leaf(leaf_value)?;
+        for node in path {
+            match node {
+                Positioned::Left(data) => {
+                    check_hash = Hash::hash_nodes(data, &check_hash)?;
+                }
+                Positioned::Right(data) => {
+                    check_hash = Hash::hash_nodes(&check_hash, data)?;
+                }
+            }
+        }
+        Ok(check_hash == root_hash)
+    }
 }
 
 #[cfg(test)]
@@ -443,4 +463,27 @@ mod tests {
             .consistency_proof(&full_root_hash, 8, &proofs_for_8)
             .unwrap());
     }
+
+    #[test]
+    fn check_inclusion_proof_works() {
+        let nodes = [
+            (true, "Gf9aBhHCtBpTYbJXQWnt1DU8q33hwi6nN4f3NhnsBgMZ"),
+            (false, "68TGAdRjeQ29eNcuFYhsX5uLakGQLgKMKp5wSyPzt9Nq"),
+            (true, "25KLEkkyCEPSBj4qMFE3AcH87mFocyJEuPJ5xzPGwDgz"),
+        ];
+        let path: Vec<Positioned<Vec<u8>>> = nodes
+            .iter()
+            .map(|(side, val)| {
+                let val = base58::decode(val).unwrap();
+                if *side {
+                    Positioned::Right(val)
+                } else {
+                    Positioned::Left(val)
+                }
+            })
+            .collect();
+        let root_hash = base58::decode("CrA5sqYe3ruf2uY7d8re7ePmyHqptHqANtMZcfZd4BvK").unwrap();
+        let leaf_value = b"\x81\xa13\xa13".to_vec(); // {"3":"3"} serialized via rmp
+        assert!(MerkleTree::check_inclusion_proof(&root_hash, &leaf_value, &path).unwrap());
+    }
 }
diff --git a/indy-data-types/src/merkle_tree/proof.rs b/indy-data-types/src/merkle_tree/proof.rs
@@ -46,13 +46,13 @@ impl Proof {
 
                 Some(Positioned::Left(ref hash)) => {
                     let combined = Hash::hash_nodes(hash, &sub.node_hash)?;
-                    let hashes_match = combined.to_vec().as_slice() == lemma.node_hash.as_slice();
+                    let hashes_match = combined == lemma.node_hash;
                     Ok(hashes_match && self.validate_lemma(sub)?)
                 }
 
                 Some(Positioned::Right(ref hash)) => {
                     let combined = Hash::hash_nodes(&sub.node_hash, hash)?;
-                    let hashes_match = combined.to_vec().as_slice() == lemma.node_hash.as_slice();
+                    let hashes_match = combined == lemma.node_hash;
                     Ok(hashes_match && self.validate_lemma(sub)?)
                 }
             },