106 lines
3.9 KiB
Diff
106 lines
3.9 KiB
Diff
--- a/src/cryptography/hazmat/backends/openssl/backend.py
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+++ b/src/cryptography/hazmat/backends/openssl/backend.py
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@@ -9,7 +9,6 @@ import calendar
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import collections
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import contextlib
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import itertools
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-import sys
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from contextlib import contextmanager
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import six
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@@ -61,6 +60,7 @@ from cryptography.hazmat.primitives.ciph
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from cryptography.hazmat.primitives.ciphers.modes import (
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CBC, CFB, CFB8, CTR, ECB, GCM, OFB
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)
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+from cryptography.hazmat.primitives.kdf import scrypt
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_MemoryBIO = collections.namedtuple("_MemoryBIO", ["bio", "char_ptr"])
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@@ -1894,9 +1894,10 @@ class Backend(object):
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def derive_scrypt(self, key_material, salt, length, n, r, p):
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buf = self._ffi.new("unsigned char[]", length)
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- res = self._lib.EVP_PBE_scrypt(key_material, len(key_material), salt,
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- len(salt), n, r, p, sys.maxsize // 2,
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- buf, length)
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+ res = self._lib.EVP_PBE_scrypt(
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+ key_material, len(key_material), salt, len(salt), n, r, p,
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+ scrypt._MEM_LIMIT, buf, length
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+ )
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self.openssl_assert(res == 1)
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return self._ffi.buffer(buf)[:]
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--- a/src/cryptography/hazmat/primitives/kdf/scrypt.py
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+++ b/src/cryptography/hazmat/primitives/kdf/scrypt.py
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@@ -4,6 +4,8 @@
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from __future__ import absolute_import, division, print_function
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+import sys
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+
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from cryptography import utils
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from cryptography.exceptions import (
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AlreadyFinalized, InvalidKey, UnsupportedAlgorithm, _Reasons
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@@ -13,6 +15,11 @@ from cryptography.hazmat.primitives impo
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from cryptography.hazmat.primitives.kdf import KeyDerivationFunction
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+# This is used by the scrypt tests to skip tests that require more memory
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+# than the MEM_LIMIT
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+_MEM_LIMIT = sys.maxsize // 2
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+
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+
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@utils.register_interface(KeyDerivationFunction)
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class Scrypt(object):
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def __init__(self, salt, length, n, r, p, backend):
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--- a/tests/hazmat/primitives/test_scrypt.py
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+++ b/tests/hazmat/primitives/test_scrypt.py
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@@ -14,7 +14,7 @@ from cryptography.exceptions import (
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AlreadyFinalized, InvalidKey, UnsupportedAlgorithm
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)
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from cryptography.hazmat.backends.interfaces import ScryptBackend
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-from cryptography.hazmat.primitives.kdf.scrypt import Scrypt
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+from cryptography.hazmat.primitives.kdf.scrypt import Scrypt, _MEM_LIMIT
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from tests.utils import load_nist_vectors, load_vectors_from_file
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@@ -22,10 +22,30 @@ vectors = load_vectors_from_file(
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os.path.join("KDF", "scrypt.txt"), load_nist_vectors)
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+def _skip_if_memory_limited(memory_limit, params):
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+ # Memory calc adapted from OpenSSL (URL split over 2 lines, thanks PEP8)
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+ # https://github.com/openssl/openssl/blob/6286757141a8c6e14d647ec733634a
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+ # e0c83d9887/crypto/evp/scrypt.c#L189-L221
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+ blen = int(params["p"]) * 128 * int(params["r"])
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+ vlen = 32 * int(params["r"]) * (int(params["n"]) + 2) * 4
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+ memory_required = blen + vlen
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+ if memory_limit < memory_required:
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+ pytest.skip("Test exceeds Scrypt memory limit. "
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+ "This is likely a 32-bit platform.")
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+
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+
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+def test_memory_limit_skip():
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+ with pytest.raises(pytest.skip.Exception):
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+ _skip_if_memory_limited(1000, {"p": 16, "r": 64, "n": 1024})
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+
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+ _skip_if_memory_limited(2 ** 31, {"p": 16, "r": 64, "n": 1024})
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+
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+
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@pytest.mark.requires_backend_interface(interface=ScryptBackend)
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class TestScrypt(object):
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@pytest.mark.parametrize("params", vectors)
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def test_derive(self, backend, params):
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+ _skip_if_memory_limited(_MEM_LIMIT, params)
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password = params["password"]
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work_factor = int(params["n"])
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block_size = int(params["r"])
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@@ -77,6 +97,7 @@ class TestScrypt(object):
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@pytest.mark.parametrize("params", vectors)
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def test_verify(self, backend, params):
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+ _skip_if_memory_limited(_MEM_LIMIT, params)
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password = params["password"]
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work_factor = int(params["n"])
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block_size = int(params["r"])
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