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# 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
import binascii
import os
import pytest
from cryptography.exceptions import (
AlreadyFinalized, InvalidKey, UnsupportedAlgorithm
)
from cryptography.hazmat.backends.interfaces import ScryptBackend
from cryptography.hazmat.primitives.kdf.scrypt import Scrypt, _MEM_LIMIT
from tests.utils import load_nist_vectors, load_vectors_from_file
vectors = load_vectors_from_file(
os.path.join("KDF", "scrypt.txt"), load_nist_vectors)
def _skip_if_memory_limited(memory_limit, params):
# Memory calc adapted from OpenSSL (URL split over 2 lines, thanks PEP8)
# https://github.com/openssl/openssl/blob/6286757141a8c6e14d647ec733634a
# e0c83d9887/crypto/evp/scrypt.c#L189-L221
blen = int(params["p"]) * 128 * int(params["r"])
vlen = 32 * int(params["r"]) * (int(params["n"]) + 2) * 4
memory_required = blen + vlen
if memory_limit < memory_required:
pytest.skip("Test exceeds Scrypt memory limit. "
"This is likely a 32-bit platform.")
def test_memory_limit_skip():
with pytest.raises(pytest.skip.Exception):
_skip_if_memory_limited(1000, {"p": 16, "r": 64, "n": 1024})
_skip_if_memory_limited(2 ** 31, {"p": 16, "r": 64, "n": 1024})
@pytest.mark.requires_backend_interface(interface=ScryptBackend)
class TestScrypt(object):
@pytest.mark.parametrize("params", vectors)
def test_derive(self, backend, params):
_skip_if_memory_limited(_MEM_LIMIT, params)
password = params["password"]
work_factor = int(params["n"])
block_size = int(params["r"])
parallelization_factor = int(params["p"])
length = int(params["length"])
salt = params["salt"]
derived_key = params["derived_key"]
scrypt = Scrypt(salt, length, work_factor, block_size,
parallelization_factor, backend)
assert binascii.hexlify(scrypt.derive(password)) == derived_key
def test_unsupported_backend(self):
work_factor = 1024
block_size = 8
parallelization_factor = 16
length = 64
salt = b"NaCl"
backend = object()
with pytest.raises(UnsupportedAlgorithm):
Scrypt(salt, length, work_factor, block_size,
parallelization_factor, backend)
def test_salt_not_bytes(self, backend):
work_factor = 1024
block_size = 8
parallelization_factor = 16
length = 64
salt = 1
with pytest.raises(TypeError):
Scrypt(salt, length, work_factor, block_size,
parallelization_factor, backend)
def test_password_not_bytes(self, backend):
password = 1
work_factor = 1024
block_size = 8
parallelization_factor = 16
length = 64
salt = b"NaCl"
scrypt = Scrypt(salt, length, work_factor, block_size,
parallelization_factor, backend)
with pytest.raises(TypeError):
scrypt.derive(password)
@pytest.mark.parametrize("params", vectors)
def test_verify(self, backend, params):
_skip_if_memory_limited(_MEM_LIMIT, params)
password = params["password"]
work_factor = int(params["n"])
block_size = int(params["r"])
parallelization_factor = int(params["p"])
length = int(params["length"])
salt = params["salt"]
derived_key = params["derived_key"]
scrypt = Scrypt(salt, length, work_factor, block_size,
parallelization_factor, backend)
assert scrypt.verify(password, binascii.unhexlify(derived_key)) is None
def test_invalid_verify(self, backend):
password = b"password"
work_factor = 1024
block_size = 8
parallelization_factor = 16
length = 64
salt = b"NaCl"
derived_key = b"fdbabe1c9d3472007856e7190d01e9fe7c6ad7cbc8237830e773"
scrypt = Scrypt(salt, length, work_factor, block_size,
parallelization_factor, backend)
with pytest.raises(InvalidKey):
scrypt.verify(password, binascii.unhexlify(derived_key))
def test_already_finalized(self, backend):
password = b"password"
work_factor = 1024
block_size = 8
parallelization_factor = 16
length = 64
salt = b"NaCl"
scrypt = Scrypt(salt, length, work_factor, block_size,
parallelization_factor, backend)
scrypt.derive(password)
with pytest.raises(AlreadyFinalized):
scrypt.derive(password)
def test_invalid_n(self, backend):
# n is less than 2
with pytest.raises(ValueError):
Scrypt(b"NaCl", 64, 1, 8, 16, backend)
# n is not a power of 2
with pytest.raises(ValueError):
Scrypt(b"NaCl", 64, 3, 8, 16, backend)
def test_invalid_r(self, backend):
with pytest.raises(ValueError):
Scrypt(b"NaCl", 64, 2, 0, 16, backend)
def test_invalid_p(self, backend):
with pytest.raises(ValueError):
Scrypt(b"NaCl", 64, 2, 8, 0, backend)
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