Add to_bytes() to COSEKeyInterface.

Add to_bytes() to COSEKeyInterface.

Author: dajiaji

README.md

@@ -646,7 +646,7 @@ r = Recipient.new(
         },
     },
 )
-r.encode(enc_key.key, recipient_key=rpk)
+r.encode(enc_key.to_bytes(), recipient_key=rpk)
 sender = COSE.new()
 encoded = sender.encode_and_encrypt(
     b"This is the content.",

cwt/algs/symmetric.py

@@ -41,6 +41,9 @@ def __init__(self, params: Dict[int, Any]):
     def key(self) -> bytes:
         return self._key
 
+    def to_bytes(self) -> bytes:
+        return self._key
+
     def to_dict(self) -> Dict[int, Any]:
         res = super().to_dict()
         res[-1] = self._key

cwt/cose_key_interface.py

@@ -104,6 +104,12 @@ def key(self) -> Any:
         """
         raise NotImplementedError
 
+    def to_bytes(self) -> bytes:
+        """
+        Serializes the body of the key as a byte string.
+        """
+        raise NotImplementedError
+
     def to_dict(self) -> Dict[int, Any]:
         """
         Returns the CBOR-like structure (Dict[int, Any]) of the COSE key.

tests/test_cose_key.py

@@ -615,3 +615,14 @@ def test_key_builder_from_jwk_with_invalid_arg(self, invalid, msg):
             COSEKey.from_jwk(invalid)
             pytest.fail("from_jwk should fail.")
         assert msg in str(err.value)
+
+    def test_cose_key_interface(self):
+        ki = COSEKeyInterface({1: 4, 3: 1})
+        with pytest.raises(NotImplementedError) as err:
+            ki.key
+            pytest.fail("key should fail.")
+        assert "" == str(err.value)
+        with pytest.raises(NotImplementedError) as err:
+            ki.to_bytes()
+            pytest.fail("to_bytes should fail.")
+        assert "" == str(err.value)

tests/test_cose_sample.py

@@ -444,7 +444,7 @@ def test_cose_usage_examples_cose_encrypt_hpke(self):
                 },
             },
         )
-        r.encode(enc_key.key, recipient_key=rpk)
+        r.encode(enc_key.to_bytes(), recipient_key=rpk)
         sender = COSE.new(alg_auto_inclusion=True)
         encoded = sender.encode_and_encrypt(
             b"This is the content.",
@@ -494,7 +494,7 @@ def test_cose_usage_examples_cose_encrypt_hpke_with_1st_layer_hpke(self):
                 },
             },
         )
-        r.encode(enc_key.key, recipient_key=rpk)
+        r.encode(enc_key.to_bytes(), recipient_key=rpk)
         sender = COSE.new()
         with pytest.raises(ValueError) as err:
             sender.encode_and_encrypt(
@@ -541,7 +541,7 @@ def test_cose_usage_examples_cose_encrypt_hpke_with_nonce(self):
                 },
             },
         )
-        r.encode(enc_key.key, recipient_key=rpk)
+        r.encode(enc_key.to_bytes(), recipient_key=rpk)
         sender = COSE.new()
         with pytest.raises(ValueError) as err:
             sender.encode_and_encrypt(