Merge pull request openwallet-foundation#78 from Indicio-tech/feature…

…/hashlink-verification

feat: Add hashlink verification code

aries_cloudagent/protocols/issue_credential/v2_0/hashlink.py

@@ -187,9 +187,50 @@ def _deserialize_metadata(cls, metadata: str) -> Dict[str, Any]:
 
         return deserialized
 
+    @classmethod
+    def _deserialize_data(cls, data: bytes) -> bytes:
+        """
+        Deserialize the data portion of a hashlink.
+
+        Parameters:
+            data -> The data portion of the hashlink
+        Returns:
+            bytes -> The decoded hash of the hashlink data
+        """
+        raw = multibase.decode(data)
+        header = raw[:2]
+        raw_hash = raw[2:]
+
+        # Currently only SHA2-256 is supported
+        if header[0] != 0x12:
+            raise Exception("Unknown hash algorithm used: {}".format(header[0]))
+
+        length = header[1]
+        if length != len(raw_hash):
+            raise Exception("hash length doesn't match length header")
+
+        return raw_hash
+
     @classmethod
     def verify(
         cls, link: str, data: Optional[bytes] = None, *, check_remote: bool = False
     ) -> bool:
         """Verify the hash of the data linked to by the hashlink."""
-        ...
+
+        link_split = link.split(cls.SEPARATOR)
+
+        if link_split[0] != cls.SCHEME:
+            return False
+
+        link_data_hash = cls._deserialize_data(link_split[1])
+
+        # TODO add check for when check_remote is true
+        if not check_remote:
+            if data is None:
+                data = b""
+            data_hash = sha256(data).digest()
+
+            if link_data_hash == data_hash:
+                return True
+
+        return False

aries_cloudagent/protocols/issue_credential/v2_0/tests/test_hashlink.py

@@ -2,6 +2,7 @@
 
 EXAMPLE_DATA = b"Hello World!"
 EXAMPLE_LINK = "hl:zQmWvQxTqbG2Z9HPJgG57jjwR154cKhbtJenbyYTWkjgF3e:zuh8iaLobXC8g9tfma1CSTtYBakXeSTkHrYA5hmD4F7dCLw8XYwZ1GWyJ3zwF"
+EXAMPLE_DATA_SHA = bytes.fromhex("7f83b1657ff1fc53b92dc18148a1d65dfc2d4b1fa3d677284addd200126d9069")
 
 
 def test_example_link():
@@ -23,3 +24,15 @@ def test_serialize_metadata():
     )
 
     assert hashlink._serialize_metadata() == EXAMPLE_LINK.split(":")[2]
+
+def test_deserialize_data():
+
+    data = EXAMPLE_LINK.split(":")[1]
+
+    assert Hashlink._deserialize_data(data) == EXAMPLE_DATA_SHA
+
+def test_verify_link():
+
+    assert Hashlink.verify(EXAMPLE_LINK, EXAMPLE_DATA)
+    assert Hashlink.verify(EXAMPLE_LINK, b"Bad Data!") == False
+    assert Hashlink.verify(EXAMPLE_LINK) == False