win32 platform

Lib/site-packages/cryptography/hazmat/primitives/cmac.py

@@ -0,0 +1,66 @@
+# This file is dual licensed under the terms of the Apache License, Version
+# 2.0, and the BSD License. See the LICENSE file in the root of this repository
+# for complete details.
+
+from __future__ import absolute_import, division, print_function
+
+from cryptography import utils
+from cryptography.exceptions import (
+    AlreadyFinalized, UnsupportedAlgorithm, _Reasons
+)
+from cryptography.hazmat.backends.interfaces import CMACBackend
+from cryptography.hazmat.primitives import ciphers, interfaces
+
+
+@utils.register_interface(interfaces.MACContext)
+class CMAC(object):
+    def __init__(self, algorithm, backend, ctx=None):
+        if not isinstance(backend, CMACBackend):
+            raise UnsupportedAlgorithm(
+                "Backend object does not implement CMACBackend.",
+                _Reasons.BACKEND_MISSING_INTERFACE
+            )
+
+        if not isinstance(algorithm, ciphers.BlockCipherAlgorithm):
+            raise TypeError(
+                "Expected instance of BlockCipherAlgorithm."
+            )
+        self._algorithm = algorithm
+
+        self._backend = backend
+        if ctx is None:
+            self._ctx = self._backend.create_cmac_ctx(self._algorithm)
+        else:
+            self._ctx = ctx
+
+    def update(self, data):
+        if self._ctx is None:
+            raise AlreadyFinalized("Context was already finalized.")
+        if not isinstance(data, bytes):
+            raise TypeError("data must be bytes.")
+        self._ctx.update(data)
+
+    def finalize(self):
+        if self._ctx is None:
+            raise AlreadyFinalized("Context was already finalized.")
+        digest = self._ctx.finalize()
+        self._ctx = None
+        return digest
+
+    def verify(self, signature):
+        if not isinstance(signature, bytes):
+            raise TypeError("signature must be bytes.")
+        if self._ctx is None:
+            raise AlreadyFinalized("Context was already finalized.")
+
+        ctx, self._ctx = self._ctx, None
+        ctx.verify(signature)
+
+    def copy(self):
+        if self._ctx is None:
+            raise AlreadyFinalized("Context was already finalized.")
+        return CMAC(
+            self._algorithm,
+            backend=self._backend,
+            ctx=self._ctx.copy()
+        )