/usr/lib/python3/dist-packages/cryptography/hazmat/backends/commoncrypto/backend.py is in python3-cryptography 1.2.3-1.
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# 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
from collections import namedtuple
from cryptography import utils
from cryptography.exceptions import InternalError
from cryptography.hazmat.backends.commoncrypto.ciphers import (
_CipherContext, _GCMCipherContext
)
from cryptography.hazmat.backends.commoncrypto.hashes import _HashContext
from cryptography.hazmat.backends.commoncrypto.hmac import _HMACContext
from cryptography.hazmat.backends.interfaces import (
CipherBackend, HMACBackend, HashBackend, PBKDF2HMACBackend
)
from cryptography.hazmat.bindings.commoncrypto.binding import Binding
from cryptography.hazmat.primitives.ciphers.algorithms import (
AES, ARC4, Blowfish, CAST5, TripleDES
)
from cryptography.hazmat.primitives.ciphers.modes import (
CBC, CFB, CFB8, CTR, ECB, GCM, OFB
)
HashMethods = namedtuple(
"HashMethods", ["ctx", "hash_init", "hash_update", "hash_final"]
)
@utils.register_interface(CipherBackend)
@utils.register_interface(HashBackend)
@utils.register_interface(HMACBackend)
@utils.register_interface(PBKDF2HMACBackend)
class Backend(object):
"""
CommonCrypto API wrapper.
"""
name = "commoncrypto"
def __init__(self):
self._binding = Binding()
self._ffi = self._binding.ffi
self._lib = self._binding.lib
self._cipher_registry = {}
self._register_default_ciphers()
self._hash_mapping = {
"md5": HashMethods(
"CC_MD5_CTX *", self._lib.CC_MD5_Init,
self._lib.CC_MD5_Update, self._lib.CC_MD5_Final
),
"sha1": HashMethods(
"CC_SHA1_CTX *", self._lib.CC_SHA1_Init,
self._lib.CC_SHA1_Update, self._lib.CC_SHA1_Final
),
"sha224": HashMethods(
"CC_SHA256_CTX *", self._lib.CC_SHA224_Init,
self._lib.CC_SHA224_Update, self._lib.CC_SHA224_Final
),
"sha256": HashMethods(
"CC_SHA256_CTX *", self._lib.CC_SHA256_Init,
self._lib.CC_SHA256_Update, self._lib.CC_SHA256_Final
),
"sha384": HashMethods(
"CC_SHA512_CTX *", self._lib.CC_SHA384_Init,
self._lib.CC_SHA384_Update, self._lib.CC_SHA384_Final
),
"sha512": HashMethods(
"CC_SHA512_CTX *", self._lib.CC_SHA512_Init,
self._lib.CC_SHA512_Update, self._lib.CC_SHA512_Final
),
}
self._supported_hmac_algorithms = {
"md5": self._lib.kCCHmacAlgMD5,
"sha1": self._lib.kCCHmacAlgSHA1,
"sha224": self._lib.kCCHmacAlgSHA224,
"sha256": self._lib.kCCHmacAlgSHA256,
"sha384": self._lib.kCCHmacAlgSHA384,
"sha512": self._lib.kCCHmacAlgSHA512,
}
self._supported_pbkdf2_hmac_algorithms = {
"sha1": self._lib.kCCPRFHmacAlgSHA1,
"sha224": self._lib.kCCPRFHmacAlgSHA224,
"sha256": self._lib.kCCPRFHmacAlgSHA256,
"sha384": self._lib.kCCPRFHmacAlgSHA384,
"sha512": self._lib.kCCPRFHmacAlgSHA512,
}
def hash_supported(self, algorithm):
return algorithm.name in self._hash_mapping
def hmac_supported(self, algorithm):
return algorithm.name in self._supported_hmac_algorithms
def create_hash_ctx(self, algorithm):
return _HashContext(self, algorithm)
def create_hmac_ctx(self, key, algorithm):
return _HMACContext(self, key, algorithm)
def cipher_supported(self, cipher, mode):
return (type(cipher), type(mode)) in self._cipher_registry
def create_symmetric_encryption_ctx(self, cipher, mode):
if isinstance(mode, GCM):
return _GCMCipherContext(
self, cipher, mode, self._lib.kCCEncrypt
)
else:
return _CipherContext(self, cipher, mode, self._lib.kCCEncrypt)
def create_symmetric_decryption_ctx(self, cipher, mode):
if isinstance(mode, GCM):
return _GCMCipherContext(
self, cipher, mode, self._lib.kCCDecrypt
)
else:
return _CipherContext(self, cipher, mode, self._lib.kCCDecrypt)
def pbkdf2_hmac_supported(self, algorithm):
return algorithm.name in self._supported_pbkdf2_hmac_algorithms
def derive_pbkdf2_hmac(self, algorithm, length, salt, iterations,
key_material):
alg_enum = self._supported_pbkdf2_hmac_algorithms[algorithm.name]
buf = self._ffi.new("char[]", length)
res = self._lib.CCKeyDerivationPBKDF(
self._lib.kCCPBKDF2,
key_material,
len(key_material),
salt,
len(salt),
alg_enum,
iterations,
buf,
length
)
self._check_cipher_response(res)
return self._ffi.buffer(buf)[:]
def _register_cipher_adapter(self, cipher_cls, cipher_const, mode_cls,
mode_const):
if (cipher_cls, mode_cls) in self._cipher_registry:
raise ValueError("Duplicate registration for: {0} {1}.".format(
cipher_cls, mode_cls)
)
self._cipher_registry[cipher_cls, mode_cls] = (cipher_const,
mode_const)
def _register_default_ciphers(self):
for mode_cls, mode_const in [
(CBC, self._lib.kCCModeCBC),
(ECB, self._lib.kCCModeECB),
(CFB, self._lib.kCCModeCFB),
(CFB8, self._lib.kCCModeCFB8),
(OFB, self._lib.kCCModeOFB),
(CTR, self._lib.kCCModeCTR),
(GCM, self._lib.kCCModeGCM),
]:
self._register_cipher_adapter(
AES,
self._lib.kCCAlgorithmAES128,
mode_cls,
mode_const
)
for mode_cls, mode_const in [
(CBC, self._lib.kCCModeCBC),
(ECB, self._lib.kCCModeECB),
(CFB, self._lib.kCCModeCFB),
(CFB8, self._lib.kCCModeCFB8),
(OFB, self._lib.kCCModeOFB),
]:
self._register_cipher_adapter(
TripleDES,
self._lib.kCCAlgorithm3DES,
mode_cls,
mode_const
)
for mode_cls, mode_const in [
(CBC, self._lib.kCCModeCBC),
(ECB, self._lib.kCCModeECB),
(CFB, self._lib.kCCModeCFB),
(OFB, self._lib.kCCModeOFB)
]:
self._register_cipher_adapter(
Blowfish,
self._lib.kCCAlgorithmBlowfish,
mode_cls,
mode_const
)
for mode_cls, mode_const in [
(CBC, self._lib.kCCModeCBC),
(ECB, self._lib.kCCModeECB),
(CFB, self._lib.kCCModeCFB),
(OFB, self._lib.kCCModeOFB),
(CTR, self._lib.kCCModeCTR)
]:
self._register_cipher_adapter(
CAST5,
self._lib.kCCAlgorithmCAST,
mode_cls,
mode_const
)
self._register_cipher_adapter(
ARC4,
self._lib.kCCAlgorithmRC4,
type(None),
self._lib.kCCModeRC4
)
def _check_cipher_response(self, response):
if response == self._lib.kCCSuccess:
return
elif response == self._lib.kCCAlignmentError:
# This error is not currently triggered due to a bug filed as
# rdar://15589470
raise ValueError(
"The length of the provided data is not a multiple of "
"the block length."
)
else:
raise InternalError(
"The backend returned an unknown error, consider filing a bug."
" Code: {0}.".format(response),
response
)
def _release_cipher_ctx(self, ctx):
"""
Called by the garbage collector and used to safely dereference and
release the context.
"""
if ctx[0] != self._ffi.NULL:
res = self._lib.CCCryptorRelease(ctx[0])
self._check_cipher_response(res)
ctx[0] = self._ffi.NULL
backend = Backend()
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