Merge pull request #123 from reaperhulk/hash-saga-sha1

Hash Saga Part 3 (API changes + SHA1)

2 files changed, 78 insertions, 0 deletions

diff --git a/cryptography/bindings/openssl/api.py b/cryptography/bindings/openssl/api.py
index 2ad6c054..5eefcdb9 100644
--- a/cryptography/bindings/openssl/api.py
+++ b/cryptography/bindings/openssl/api.py
@@ -141,5 +141,35 @@ class API(object):
         assert res != 0
         return self.ffi.buffer(buf)[:outlen[0]]
 
+    def supports_hash(self, hash_cls):
+        return (self.ffi.NULL !=
+                self.lib.EVP_get_digestbyname(hash_cls.name.encode("ascii")))
+
+    def create_hash_context(self, hashobject):
+        ctx = self.lib.EVP_MD_CTX_create()
+        ctx = self.ffi.gc(ctx, self.lib.EVP_MD_CTX_destroy)
+        evp_md = self.lib.EVP_get_digestbyname(hashobject.name.encode("ascii"))
+        assert evp_md != self.ffi.NULL
+        res = self.lib.EVP_DigestInit_ex(ctx, evp_md, self.ffi.NULL)
+        assert res != 0
+        return ctx
+
+    def update_hash_context(self, ctx, data):
+        res = self.lib.EVP_DigestUpdate(ctx, data, len(data))
+        assert res != 0
+
+    def finalize_hash_context(self, ctx, digest_size):
+        buf = self.ffi.new("unsigned char[]", digest_size)
+        res = self.lib.EVP_DigestFinal_ex(ctx, buf, self.ffi.NULL)
+        assert res != 0
+        return self.ffi.buffer(buf)[:digest_size]
+
+    def copy_hash_context(self, ctx):
+        copied_ctx = self.lib.EVP_MD_CTX_create()
+        copied_ctx = self.ffi.gc(copied_ctx, self.lib.EVP_MD_CTX_destroy)
+        res = self.lib.EVP_MD_CTX_copy_ex(copied_ctx, ctx)
+        assert res != 0
+        return copied_ctx
+
 
 api = API()
diff --git a/cryptography/primitives/hashes.py b/cryptography/primitives/hashes.py
new file mode 100644
index 00000000..d74287f9
--- /dev/null
+++ b/cryptography/primitives/hashes.py
@@ -0,0 +1,48 @@
+# 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
+
+import binascii
+
+from cryptography.bindings import _default_api
+
+
+class BaseHash(object):
+    def __init__(self, api=None, ctx=None):
+        if api is None:
+            api = _default_api
+        self._api = api
+        self._ctx = self._api.create_hash_context(self) if ctx is None else ctx
+
+    def update(self, string):
+        self._api.update_hash_context(self._ctx, string)
+
+    def copy(self):
+        return self.__class__(ctx=self._copy_ctx())
+
+    def digest(self):
+        return self._api.finalize_hash_context(self._copy_ctx(),
+                                               self.digest_size)
+
+    def hexdigest(self):
+        return binascii.hexlify(self.digest()).decode("ascii")
+
+    def _copy_ctx(self):
+        return self._api.copy_hash_context(self._ctx)
+
+
+class SHA1(BaseHash):
+    name = "sha1"
+    digest_size = 20
+    block_size = 64