Bug fixes and docs

cose/algorithms.py

@@ -34,6 +34,8 @@
 
 
 class CoseAlgorithm(_CoseAttribute, ABC):
+    """ Base class for all COSE algorithms. """
+
     _registered_algorithms = {}
 
     @classmethod
@@ -45,7 +47,7 @@ class _HashAlg(CoseAlgorithm, ABC):
     #: Set in derived class to hash constructor
     hash_cls = None
     #: Set in derived class to optional trucation size in byte count
-    truc_size: Optional[int] = None
+    trunc_size: Optional[int] = None
 
     @classmethod
     def get_hash_func(cls) -> HashAlgorithm:
@@ -57,8 +59,8 @@ def compute_hash(cls, data: bytes) -> bytes:
         h.update(data)
         digest = h.finalize()
 
-        if cls.truc_size:
-            digest = digest[:cls.truc_size]
+        if cls.trunc_size:
+            digest = digest[:cls.trunc_size]
 
         return digest
 
@@ -633,7 +635,7 @@ class Sha512Trunc256(_HashAlg):
     identifier = -17
     fullname = "SHA-512/256"
     hash_cls = SHA512
-    truc_size = 32
+    trunc_size = 32
 
 
 @CoseAlgorithm.register_attribute()
@@ -648,7 +650,7 @@ class Sha256Trunc64(_HashAlg):
     identifier = -15
     fullname = "SHA-256/64"
     hash_cls = SHA256
-    truc_size = 8
+    trunc_size = 8
 
 
 @CoseAlgorithm.register_attribute()

cose/keys/ec2.py

@@ -118,10 +118,10 @@ def crv(self) -> Optional[Type['CoseCurve']]:
             raise CoseInvalidKey("EC2 COSE key must have the EC2KpCurve attribute")
 
     @crv.setter
-    def crv(self, crv: Type['CoseCurve']):
+    def crv(self, crv: Union[Type['CoseCurve'], int, str]):
         if crv not in [P256, P384, P521] \
-                or crv not in [P256.identifier, P384.identifier, P521.identifier] \
-                or crv not in [P256.fullname, P384.fullname, P521.fullname]:
+                and crv not in [P256.identifier, P384.identifier, P521.identifier] \
+                and crv not in [P256.fullname, P384.fullname, P521.fullname]:
             raise CoseIllegalCurve("Invalid COSE curve attribute")
         else:
             self.store[EC2KpCurve] = CoseCurve.from_id(crv)

cose/keys/keyparam.py

@@ -6,6 +6,10 @@
 from cose.utils import _CoseAttribute
 
 
+#########################################
+# Base Key Parameters
+#########################################
+
 class KeyParam(_CoseAttribute, ABC):
     _registered_algorithms = {}
 
@@ -44,6 +48,10 @@ class KpBaseIV(KeyParam):
     fullname = 'BASE_IV'
 
 
+#########################################
+# EC2 Key Parameters
+#########################################
+
 class EC2KeyParam(_CoseAttribute, ABC):
     _registered_algorithms = {}
     _registered_algorithms.update(KeyParam.get_registered_classes())
@@ -77,6 +85,10 @@ class EC2KpD(EC2KeyParam):
     fullname = "D"
 
 
+#########################################
+# OKP Key Parameters
+#########################################
+
 class OKPKeyParam(_CoseAttribute, ABC):
     _registered_algorithms = {}
     _registered_algorithms.update(KeyParam.get_registered_classes())
@@ -104,6 +116,10 @@ class OKPKpX(OKPKeyParam):
     fullname = "X"
 
 
+#########################################
+# Symmetric Key Parameters
+#########################################
+
 class SymmetricKeyParam(_CoseAttribute, ABC):
     _registered_algorithms = {}
     _registered_algorithms.update(KeyParam.get_registered_classes())

cose/keys/okp.py

@@ -63,6 +63,15 @@ def _key_transform(key: Union[Type['OKPKeyParam'], Type['KeyParam'], str, int]):
 
     def __init__(self, crv: Union[Type['CoseCurve'], str, int], x: bytes = b'', d: bytes = b'',
                  optional_params: Optional[dict] = None):
+        """
+        Create an COSE OKP key.
+
+        :param crv: An OKP elliptic curve.
+        :param x: Public value of the OKP key.
+        :param d: Private value of the OKP key.
+        :param optional_params: A dictionary with optional key parameters.
+        """
+
         transformed_dict = {}
 
         if len(x) == 0 and len(d) == 0:
@@ -110,10 +119,10 @@ def crv(self) -> Optional[Type['CoseCurve']]:
             raise CoseInvalidKey("OKP COSE key must have the OKP KpCurve attribute")
 
     @crv.setter
-    def crv(self, crv: Type['CoseCurve']):
+    def crv(self, crv: Union[Type['CoseCurve'], int, str]):
         if crv not in [X25519, X448, Ed25519, Ed448] \
-                or crv not in [X25519.identifier, X448.identifier, Ed25519.identifier, Ed448.identifier] \
-                or crv not in [X25519.fullname, X448.fullname, Ed25519.fullname, Ed448.identifier]:
+                and crv not in [X25519.identifier, X448.identifier, Ed25519.identifier, Ed448.identifier] \
+                and crv not in [X25519.fullname, X448.fullname, Ed25519.fullname, Ed448.identifier]:
             raise CoseIllegalCurve("Invalid COSE curve attribute")
         else:
             self.store[OKPKpCurve] = CoseCurve.from_id(crv)
@@ -183,7 +192,7 @@ def generate_key(curve: Union[Type['CoseCurve'], str, int], optional_params: dic
             d=private_key.private_bytes(encoding, private_format, encryption),
             optional_params=optional_params)
 
-    def __delitem__(self, key):
+    def __delitem__(self, key: Union['KeyParam', str, int]):
         if self._key_transform(key) != KpKty and self._key_transform(key) != OKPKpCurve:
             if self._key_transform(key) == OKPKpD and OKPKpX not in self.store:
                 pass

tests/test_okp_keys.py

@@ -5,7 +5,7 @@
 
 from cose.algorithms import EdDSA
 from cose.curves import Ed448, Ed25519, X448, X25519
-from cose.exceptions import CoseInvalidKey, CoseIllegalKeyType
+from cose.exceptions import CoseInvalidKey, CoseIllegalKeyType, CoseIllegalCurve
 from cose.keys import OKPKey, CoseKey
 from cose.keys.keyops import SignOp
 from cose.keys.keyparam import KpKty, OKPKpCurve, OKPKpX, OKPKpD, KpAlg, KpKeyOps
@@ -156,3 +156,24 @@ def test_unknown_key_attributes():
     key = CoseKey.decode(unhexlify(key))
 
     assert "subject name" in key
+
+
+def test_key_set_curve():
+    key = 'a401012006215820898ff79a02067a16ea1eccb90fa52246f5aa4dd6ec076bba0259d904b7ec8b0c2358208f781a095372f85b6d' \
+          '9f6109ae422611734d7dbfa0069a2df2935bb2e053bf35'
+    key = CoseKey.decode(unhexlify(key))
+
+    assert key.crv == Ed25519
+
+    key.crv = X25519
+
+    assert key.crv == X25519
+
+    with pytest.raises(CoseIllegalCurve) as excinfo:
+        key.crv = 3
+
+    assert "Invalid COSE curve attribute" in str(excinfo.value)
+
+    key.crv = X448.identifier
+
+    assert key.crv == X448