Move metadata class model de/serialization to sub-package

tuf/api/serialization/json.py

@@ -0,0 +1,55 @@
+"""TUF role metadata JSON serialization and deserialization.
+
+This module provides concrete implementations to serialize and deserialize TUF
+role metadata to and from the JSON wireline format for transportation, and
+to serialize the 'signed' part of TUF role metadata to the OLPC Canonical JSON
+format for signature generation and verification.
+
+"""
+import json
+
+from securesystemslib.formats import encode_canonical
+
+from tuf.api.metadata import Metadata, Signed
+from tuf.api.serialization import (MetadataSerializer,
+ MetadataDeserializer,
+ SignedSerializer)
+
+
+class JSONDeserializer(MetadataDeserializer):
+ """Provides JSON-to-Metadata deserialize method. """
+
+ def deserialize(self, raw_data: bytes) -> Metadata:
+ """Deserialize utf-8 encoded JSON bytes into Metadata object. """
+ _dict = json.loads(raw_data.decode("utf-8"))
+ return Metadata.from_dict(_dict)
+
+
+class JSONSerializer(MetadataSerializer):
+ """A Metadata-to-JSON serialize method.
+
+ Attributes:
+ compact: A boolean indicating if the JSON bytes generated in
+ 'serialize' should be compact by excluding whitespace.
+
+ """
+ def __init__(self, compact: bool = False) -> None:
+ self.compact = compact
+
+ def serialize(self, metadata_obj: Metadata) -> bytes:
+ """Serialize Metadata object into utf-8 encoded JSON bytes. """
+ indent = (None if self.compact else 1)
+ separators=((',', ':') if self.compact else (',', ': '))
+ return json.dumps(metadata_obj.to_dict(),
+ indent=indent,
+ separators=separators,
+ sort_keys=True).encode("utf-8")
+
+
+class CanonicalJSONSerializer(SignedSerializer):
+ """A Signed-to-Canonical JSON 'serialize' method. """
+
+ def serialize(self, signed_obj: Signed) -> bytes:
+ """Serialize Signed object into utf-8 encoded Canonical JSON bytes. """
+ signed_dict = signed_obj.to_dict()
+ return encode_canonical(signed_dict).encode("utf-8")