1 files changed, 71 insertions, 0 deletions
diff --git a/src/cryptography/hazmat/backends/openssl/hashes.py b/src/cryptography/hazmat/backends/openssl/hashes.py
new file mode 100644
index 00000000..591c014a
--- /dev/null
+++ b/src/cryptography/hazmat/backends/openssl/hashes.py
@@ -0,0 +1,71 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import, division, print_function
+
+
+from cryptography import utils
+from cryptography.exceptions import UnsupportedAlgorithm, _Reasons
+from cryptography.hazmat.primitives import interfaces
+
+
+@utils.register_interface(interfaces.HashContext)
+class _HashContext(object):
+    def __init__(self, backend, algorithm, ctx=None):
+        self._algorithm = algorithm
+
+        self._backend = backend
+
+        if ctx is None:
+            ctx = self._backend._lib.EVP_MD_CTX_create()
+            ctx = self._backend._ffi.gc(ctx,
+                                        self._backend._lib.EVP_MD_CTX_destroy)
+            evp_md = self._backend._lib.EVP_get_digestbyname(
+                algorithm.name.encode("ascii"))
+            if evp_md == self._backend._ffi.NULL:
+                raise UnsupportedAlgorithm(
+                    "{0} is not a supported hash on this backend.".format(
+                        algorithm.name),
+                    _Reasons.UNSUPPORTED_HASH
+                )
+            res = self._backend._lib.EVP_DigestInit_ex(ctx, evp_md,
+                                                       self._backend._ffi.NULL)
+            assert res != 0
+
+        self._ctx = ctx
+
+    algorithm = utils.read_only_property("_algorithm")
+
+    def copy(self):
+        copied_ctx = self._backend._lib.EVP_MD_CTX_create()
+        copied_ctx = self._backend._ffi.gc(
+            copied_ctx, self._backend._lib.EVP_MD_CTX_destroy
+        )
+        res = self._backend._lib.EVP_MD_CTX_copy_ex(copied_ctx, self._ctx)
+        assert res != 0
+        return _HashContext(self._backend, self.algorithm, ctx=copied_ctx)
+
+    def update(self, data):
+        res = self._backend._lib.EVP_DigestUpdate(self._ctx, data, len(data))
+        assert res != 0
+
+    def finalize(self):
+        buf = self._backend._ffi.new("unsigned char[]",
+                                     self._backend._lib.EVP_MAX_MD_SIZE)
+        outlen = self._backend._ffi.new("unsigned int *")
+        res = self._backend._lib.EVP_DigestFinal_ex(self._ctx, buf, outlen)
+        assert res != 0
+        assert outlen[0] == self.algorithm.digest_size
+        res = self._backend._lib.EVP_MD_CTX_cleanup(self._ctx)
+        assert res == 1
+        return self._backend._ffi.buffer(buf)[:outlen[0]]