WIP: Add bindings for siphash-2-4 (#206)

* Added binary bindings for SipHash-2-4

used as cypto_shorthash in libsodium

* Add python shim

* Add test for python shim.

* Make key a positional parameter.

Clarify the length must be EXACTLY equal to KEYBYTES

* Add a test for short passwords

and the requested comment about test vectors' origin.

* Try and please flake8

* Raise exception as requested in review

src/bindings/crypto_shorthash.h

@@ -0,0 +1,23 @@
+/* Copyright 2013 Donald Stufft and individual contributors
+ *
+ * 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.
+ */
+
+
+// size_t crypto_hash_bytes();
+
+size_t crypto_shorthash_siphash24_bytes();
+size_t crypto_shorthash_siphash24_keybytes();
+
+int crypto_shorthash_siphash24(unsigned char *out, const unsigned char *in,
+                               unsigned long long inlen, const unsigned char *k);

src/nacl/bindings/__init__.py

@@ -34,6 +34,11 @@
     crypto_secretbox_NONCEBYTES, crypto_secretbox_ZEROBYTES,
     crypto_secretbox_open
 )
+from nacl.bindings.crypto_shorthash import (
+    BYTES as crypto_shorthash_siphash24_BYTES,
+    KEYBYTES as crypto_shorthash_siphash24_KEYBYTES,
+    crypto_shorthash_siphash24
+)
 from nacl.bindings.crypto_sign import (
     crypto_sign, crypto_sign_BYTES, crypto_sign_PUBLICKEYBYTES,
     crypto_sign_SECRETKEYBYTES, crypto_sign_SEEDBYTES,
@@ -77,6 +82,10 @@
     "crypto_secretbox",
     "crypto_secretbox_open",
 
+    "crypto_shorthash_siphash24_BYTES",
+    "crypto_shorthash_siphash24_KEYBYTES",
+    "crypto_shorthash_siphash24",
+
     "crypto_sign_BYTES",
     "crypto_sign_SEEDBYTES",
     "crypto_sign_PUBLICKEYBYTES",

src/nacl/bindings/crypto_shorthash.py

@@ -0,0 +1,38 @@
+# Copyright 2016 Donald Stufft and individual contributors
+#
+# 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 nacl._sodium import ffi, lib
+
+BYTES = lib.crypto_shorthash_siphash24_bytes()
+KEYBYTES = lib.crypto_shorthash_siphash24_keybytes()
+
+
+def crypto_shorthash_siphash24(data, key):
+    """Compute a fast, cryptographic quality, keyed hash of the input data
+
+    :param data:
+    :type data: bytes
+    :param key: len(key) must be equal to
+                :py:data:`.KEYBYTES` (16)
+    :type key: bytes
+    """
+    if len(key) != KEYBYTES:
+        raise ValueError("Key length must be {0} bytes".format(KEYBYTES))
+    digest = ffi.new("unsigned char[]", BYTES)
+    rc = lib.crypto_shorthash_siphash24(digest, data, len(data), key)
+
+    assert rc == 0
+    return ffi.buffer(digest, BYTES)[:]

tests/test_shorthash.py

@@ -0,0 +1,136 @@
+# Copyright 2016 Donald Stufft and individual contributors
+#
+# 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 pytest
+
+from nacl.bindings import crypto_shorthash_siphash24
+
+HASHES = [
+    b"\x31\x0e\x0e\xdd\x47\xdb\x6f\x72",
+    b"\xfd\x67\xdc\x93\xc5\x39\xf8\x74",
+    b"\x5a\x4f\xa9\xd9\x09\x80\x6c\x0d",
+    b"\x2d\x7e\xfb\xd7\x96\x66\x67\x85",
+    b"\xb7\x87\x71\x27\xe0\x94\x27\xcf",
+    b"\x8d\xa6\x99\xcd\x64\x55\x76\x18",
+    b"\xce\xe3\xfe\x58\x6e\x46\xc9\xcb",
+    b"\x37\xd1\x01\x8b\xf5\x00\x02\xab",
+    b"\x62\x24\x93\x9a\x79\xf5\xf5\x93",
+    b"\xb0\xe4\xa9\x0b\xdf\x82\x00\x9e",
+    b"\xf3\xb9\xdd\x94\xc5\xbb\x5d\x7a",
+    b"\xa7\xad\x6b\x22\x46\x2f\xb3\xf4",
+    b"\xfb\xe5\x0e\x86\xbc\x8f\x1e\x75",
+    b"\x90\x3d\x84\xc0\x27\x56\xea\x14",
+    b"\xee\xf2\x7a\x8e\x90\xca\x23\xf7",
+    b"\xe5\x45\xbe\x49\x61\xca\x29\xa1",
+    b"\xdb\x9b\xc2\x57\x7f\xcc\x2a\x3f",
+    b"\x94\x47\xbe\x2c\xf5\xe9\x9a\x69",
+    b"\x9c\xd3\x8d\x96\xf0\xb3\xc1\x4b",
+    b"\xbd\x61\x79\xa7\x1d\xc9\x6d\xbb",
+    b"\x98\xee\xa2\x1a\xf2\x5c\xd6\xbe",
+    b"\xc7\x67\x3b\x2e\xb0\xcb\xf2\xd0",
+    b"\x88\x3e\xa3\xe3\x95\x67\x53\x93",
+    b"\xc8\xce\x5c\xcd\x8c\x03\x0c\xa8",
+    b"\x94\xaf\x49\xf6\xc6\x50\xad\xb8",
+    b"\xea\xb8\x85\x8a\xde\x92\xe1\xbc",
+    b"\xf3\x15\xbb\x5b\xb8\x35\xd8\x17",
+    b"\xad\xcf\x6b\x07\x63\x61\x2e\x2f",
+    b"\xa5\xc9\x1d\xa7\xac\xaa\x4d\xde",
+    b"\x71\x65\x95\x87\x66\x50\xa2\xa6",
+    b"\x28\xef\x49\x5c\x53\xa3\x87\xad",
+    b"\x42\xc3\x41\xd8\xfa\x92\xd8\x32",
+    b"\xce\x7c\xf2\x72\x2f\x51\x27\x71",
+    b"\xe3\x78\x59\xf9\x46\x23\xf3\xa7",
+    b"\x38\x12\x05\xbb\x1a\xb0\xe0\x12",
+    b"\xae\x97\xa1\x0f\xd4\x34\xe0\x15",
+    b"\xb4\xa3\x15\x08\xbe\xff\x4d\x31",
+    b"\x81\x39\x62\x29\xf0\x90\x79\x02",
+    b"\x4d\x0c\xf4\x9e\xe5\xd4\xdc\xca",
+    b"\x5c\x73\x33\x6a\x76\xd8\xbf\x9a",
+    b"\xd0\xa7\x04\x53\x6b\xa9\x3e\x0e",
+    b"\x92\x59\x58\xfc\xd6\x42\x0c\xad",
+    b"\xa9\x15\xc2\x9b\xc8\x06\x73\x18",
+    b"\x95\x2b\x79\xf3\xbc\x0a\xa6\xd4",
+    b"\xf2\x1d\xf2\xe4\x1d\x45\x35\xf9",
+    b"\x87\x57\x75\x19\x04\x8f\x53\xa9",
+    b"\x10\xa5\x6c\xf5\xdf\xcd\x9a\xdb",
+    b"\xeb\x75\x09\x5c\xcd\x98\x6c\xd0",
+    b"\x51\xa9\xcb\x9e\xcb\xa3\x12\xe6",
+    b"\x96\xaf\xad\xfc\x2c\xe6\x66\xc7",
+    b"\x72\xfe\x52\x97\x5a\x43\x64\xee",
+    b"\x5a\x16\x45\xb2\x76\xd5\x92\xa1",
+    b"\xb2\x74\xcb\x8e\xbf\x87\x87\x0a",
+    b"\x6f\x9b\xb4\x20\x3d\xe7\xb3\x81",
+    b"\xea\xec\xb2\xa3\x0b\x22\xa8\x7f",
+    b"\x99\x24\xa4\x3c\xc1\x31\x57\x24",
+    b"\xbd\x83\x8d\x3a\xaf\xbf\x8d\xb7",
+    b"\x0b\x1a\x2a\x32\x65\xd5\x1a\xea",
+    b"\x13\x50\x79\xa3\x23\x1c\xe6\x60",
+    b"\x93\x2b\x28\x46\xe4\xd7\x06\x66",
+    b"\xe1\x91\x5f\x5c\xb1\xec\xa4\x6c",
+    b"\xf3\x25\x96\x5c\xa1\x6d\x62\x9f",
+    b"\x57\x5f\xf2\x8e\x60\x38\x1b\xe5",
+    b"\x72\x45\x06\xeb\x4c\x32\x8a\x95"
+]
+
+MESG = (
+    b"\x00\x01\x02\x03\x04\x05\x06\x07"
+    b"\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
+    b"\x10\x11\x12\x13\x14\x15\x16\x17"
+    b"\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"
+    b"\x20\x21\x22\x23\x24\x25\x26\x27"
+    b"\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f"
+    b"\x30\x31\x32\x33\x34\x35\x36\x37"
+    b"\x38\x39\x3a\x3b\x3c\x3d\x3e"
+)
+
+KEY = (
+    b"\x00\x01\x02\x03\x04\x05\x06\x07"
+    b"\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
+)
+
+
+def sip24_vectors():
+    """Generate test vectors using data from the reference implementation's
+    test defined in  https://github.com/veorq/SipHash/blob/master/main.c
+
+    The key, the messages sequence and the expected hashes are all coming
+    from that file's definitions.
+    """
+    vectors = []
+    for i, expected in enumerate(HASHES):
+        mesg = MESG[0:i]
+        vectors.append((mesg, KEY, expected))
+    return vectors
+
+
+@pytest.mark.parametrize(("inp", "key", "expected"),
+                         sip24_vectors()
+                         )
+def test_crypto_shorthash_siphash24(inp, key, expected):
+    rs = crypto_shorthash_siphash24(inp, key)
+    assert rs == expected
+
+
+@pytest.mark.parametrize(("inp", "key", "expected"), [
+    (
+        b'\00',
+        b'\x00\x01\x02\x03\x04\x05\x06\x07',
+        b''
+    )
+])
+def test_shortened_key(inp, key, expected):
+    with pytest.raises(ValueError):
+        crypto_shorthash_siphash24(inp, key)