Current File : //var/opt/nydus/ops/oscrypto/_win/symmetric.py
# coding: utf-8
from __future__ import unicode_literals, division, absolute_import, print_function
from .._errors import pretty_message
from .._ffi import (
buffer_from_bytes,
bytes_from_buffer,
deref,
new,
null,
pointer_set,
struct,
struct_bytes,
unwrap,
write_to_buffer,
)
from .util import rand_bytes
from .. import backend
from .._types import type_name, byte_cls
_backend = backend()
if _backend == 'winlegacy':
from ._advapi32 import advapi32, Advapi32Const, handle_error, open_context_handle, close_context_handle
else:
from ._cng import bcrypt, BcryptConst, handle_error, open_alg_handle, close_alg_handle
__all__ = [
'aes_cbc_no_padding_decrypt',
'aes_cbc_no_padding_encrypt',
'aes_cbc_pkcs7_decrypt',
'aes_cbc_pkcs7_encrypt',
'des_cbc_pkcs5_decrypt',
'des_cbc_pkcs5_encrypt',
'rc2_cbc_pkcs5_decrypt',
'rc2_cbc_pkcs5_encrypt',
'rc4_decrypt',
'rc4_encrypt',
'tripledes_cbc_pkcs5_decrypt',
'tripledes_cbc_pkcs5_encrypt',
]
def aes_cbc_no_padding_encrypt(key, data, iv):
"""
Encrypts plaintext using AES in CBC mode with a 128, 192 or 256 bit key and
no padding. This means the ciphertext must be an exact multiple of 16 bytes
long.
:param key:
The encryption key - a byte string either 16, 24 or 32 bytes long
:param data:
The plaintext - a byte string
:param iv:
The initialization vector - either a byte string 16-bytes long or None
to generate an IV
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A tuple of two byte strings (iv, ciphertext)
"""
if len(key) not in [16, 24, 32]:
raise ValueError(pretty_message(
'''
key must be either 16, 24 or 32 bytes (128, 192 or 256 bits)
long - is %s
''',
len(key)
))
if not iv:
iv = rand_bytes(16)
elif len(iv) != 16:
raise ValueError(pretty_message(
'''
iv must be 16 bytes long - is %s
''',
len(iv)
))
if len(data) % 16 != 0:
raise ValueError(pretty_message(
'''
data must be a multiple of 16 bytes long - is %s
''',
len(data)
))
return (iv, _encrypt('aes', key, data, iv, False))
def aes_cbc_no_padding_decrypt(key, data, iv):
"""
Decrypts AES ciphertext in CBC mode using a 128, 192 or 256 bit key and no
padding.
:param key:
The encryption key - a byte string either 16, 24 or 32 bytes long
:param data:
The ciphertext - a byte string
:param iv:
The initialization vector - a byte string 16-bytes long
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the plaintext
"""
if len(key) not in [16, 24, 32]:
raise ValueError(pretty_message(
'''
key must be either 16, 24 or 32 bytes (128, 192 or 256 bits)
long - is %s
''',
len(key)
))
if len(iv) != 16:
raise ValueError(pretty_message(
'''
iv must be 16 bytes long - is %s
''',
len(iv)
))
return _decrypt('aes', key, data, iv, False)
def aes_cbc_pkcs7_encrypt(key, data, iv):
"""
Encrypts plaintext using AES in CBC mode with a 128, 192 or 256 bit key and
PKCS#7 padding.
:param key:
The encryption key - a byte string either 16, 24 or 32 bytes long
:param data:
The plaintext - a byte string
:param iv:
The initialization vector - either a byte string 16-bytes long or None
to generate an IV
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A tuple of two byte strings (iv, ciphertext)
"""
if len(key) not in [16, 24, 32]:
raise ValueError(pretty_message(
'''
key must be either 16, 24 or 32 bytes (128, 192 or 256 bits)
long - is %s
''',
len(key)
))
if not iv:
iv = rand_bytes(16)
elif len(iv) != 16:
raise ValueError(pretty_message(
'''
iv must be 16 bytes long - is %s
''',
len(iv)
))
return (iv, _encrypt('aes', key, data, iv, True))
def aes_cbc_pkcs7_decrypt(key, data, iv):
"""
Decrypts AES ciphertext in CBC mode using a 128, 192 or 256 bit key
:param key:
The encryption key - a byte string either 16, 24 or 32 bytes long
:param data:
The ciphertext - a byte string
:param iv:
The initialization vector - a byte string 16-bytes long
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the plaintext
"""
if len(key) not in [16, 24, 32]:
raise ValueError(pretty_message(
'''
key must be either 16, 24 or 32 bytes (128, 192 or 256 bits)
long - is %s
''',
len(key)
))
if len(iv) != 16:
raise ValueError(pretty_message(
'''
iv must be 16 bytes long - is %s
''',
len(iv)
))
return _decrypt('aes', key, data, iv, True)
def rc4_encrypt(key, data):
"""
Encrypts plaintext using RC4 with a 40-128 bit key
:param key:
The encryption key - a byte string 5-16 bytes long
:param data:
The plaintext - a byte string
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the ciphertext
"""
if len(key) < 5 or len(key) > 16:
raise ValueError(pretty_message(
'''
key must be 5 to 16 bytes (40 to 128 bits) long - is %s
''',
len(key)
))
return _encrypt('rc4', key, data, None, None)
def rc4_decrypt(key, data):
"""
Decrypts RC4 ciphertext using a 40-128 bit key
:param key:
The encryption key - a byte string 5-16 bytes long
:param data:
The ciphertext - a byte string
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the plaintext
"""
if len(key) < 5 or len(key) > 16:
raise ValueError(pretty_message(
'''
key must be 5 to 16 bytes (40 to 128 bits) long - is %s
''',
len(key)
))
return _decrypt('rc4', key, data, None, None)
def rc2_cbc_pkcs5_encrypt(key, data, iv):
"""
Encrypts plaintext using RC2 with a 64 bit key
:param key:
The encryption key - a byte string 8 bytes long
:param data:
The plaintext - a byte string
:param iv:
The 8-byte initialization vector to use - a byte string - set as None
to generate an appropriate one
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A tuple of two byte strings (iv, ciphertext)
"""
if len(key) < 5 or len(key) > 16:
raise ValueError(pretty_message(
'''
key must be 5 to 16 bytes (40 to 128 bits) long - is %s
''',
len(key)
))
if not iv:
iv = rand_bytes(8)
elif len(iv) != 8:
raise ValueError(pretty_message(
'''
iv must be 8 bytes long - is %s
''',
len(iv)
))
return (iv, _encrypt('rc2', key, data, iv, True))
def rc2_cbc_pkcs5_decrypt(key, data, iv):
"""
Decrypts RC2 ciphertext using a 64 bit key
:param key:
The encryption key - a byte string 8 bytes long
:param data:
The ciphertext - a byte string
:param iv:
The initialization vector used for encryption - a byte string
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the plaintext
"""
if len(key) < 5 or len(key) > 16:
raise ValueError(pretty_message(
'''
key must be 5 to 16 bytes (40 to 128 bits) long - is %s
''',
len(key)
))
if len(iv) != 8:
raise ValueError(pretty_message(
'''
iv must be 8 bytes long - is %s
''',
len(iv)
))
return _decrypt('rc2', key, data, iv, True)
def tripledes_cbc_pkcs5_encrypt(key, data, iv):
"""
Encrypts plaintext using 3DES in either 2 or 3 key mode
:param key:
The encryption key - a byte string 16 or 24 bytes long (2 or 3 key mode)
:param data:
The plaintext - a byte string
:param iv:
The 8-byte initialization vector to use - a byte string - set as None
to generate an appropriate one
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A tuple of two byte strings (iv, ciphertext)
"""
if len(key) != 16 and len(key) != 24:
raise ValueError(pretty_message(
'''
key must be 16 bytes (2 key) or 24 bytes (3 key) long - is %s
''',
len(key)
))
if not iv:
iv = rand_bytes(8)
elif len(iv) != 8:
raise ValueError(pretty_message(
'''
iv must be 8 bytes long - is %s
''',
len(iv)
))
cipher = 'tripledes_3key'
if len(key) == 16:
cipher = 'tripledes_2key'
return (iv, _encrypt(cipher, key, data, iv, True))
def tripledes_cbc_pkcs5_decrypt(key, data, iv):
"""
Decrypts 3DES ciphertext in either 2 or 3 key mode
:param key:
The encryption key - a byte string 16 or 24 bytes long (2 or 3 key mode)
:param data:
The ciphertext - a byte string
:param iv:
The initialization vector used for encryption - a byte string
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the plaintext
"""
if len(key) != 16 and len(key) != 24:
raise ValueError(pretty_message(
'''
key must be 16 bytes (2 key) or 24 bytes (3 key) long - is %s
''',
len(key)
))
if len(iv) != 8:
raise ValueError(pretty_message(
'''
iv must be 8 bytes long - is %s
''',
len(iv)
))
cipher = 'tripledes_3key'
if len(key) == 16:
cipher = 'tripledes_2key'
return _decrypt(cipher, key, data, iv, True)
def des_cbc_pkcs5_encrypt(key, data, iv):
"""
Encrypts plaintext using DES with a 56 bit key
:param key:
The encryption key - a byte string 8 bytes long (includes error
correction bits)
:param data:
The plaintext - a byte string
:param iv:
The 8-byte initialization vector to use - a byte string - set as None
to generate an appropriate one
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A tuple of two byte strings (iv, ciphertext)
"""
if len(key) != 8:
raise ValueError(pretty_message(
'''
key must be 8 bytes (56 bits + 8 parity bits) long - is %s
''',
len(key)
))
if not iv:
iv = rand_bytes(8)
elif len(iv) != 8:
raise ValueError(pretty_message(
'''
iv must be 8 bytes long - is %s
''',
len(iv)
))
return (iv, _encrypt('des', key, data, iv, True))
def des_cbc_pkcs5_decrypt(key, data, iv):
"""
Decrypts DES ciphertext using a 56 bit key
:param key:
The encryption key - a byte string 8 bytes long (includes error
correction bits)
:param data:
The ciphertext - a byte string
:param iv:
The initialization vector used for encryption - a byte string
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the plaintext
"""
if len(key) != 8:
raise ValueError(pretty_message(
'''
key must be 8 bytes (56 bits + 8 parity bits) long - is %s
''',
len(key)
))
if len(iv) != 8:
raise ValueError(pretty_message(
'''
iv must be 8 bytes long - is %s
''',
len(iv)
))
return _decrypt('des', key, data, iv, True)
def _advapi32_create_handles(cipher, key, iv):
"""
Creates an HCRYPTPROV and HCRYPTKEY for symmetric encryption/decryption. The
HCRYPTPROV must be released by close_context_handle() and the
HCRYPTKEY must be released by advapi32.CryptDestroyKey() when done.
:param cipher:
A unicode string of "aes", "des", "tripledes_2key", "tripledes_3key",
"rc2", "rc4"
:param key:
A byte string of the symmetric key
:param iv:
The initialization vector - a byte string - unused for RC4
:return:
A tuple of (HCRYPTPROV, HCRYPTKEY)
"""
context_handle = None
if cipher == 'aes':
algorithm_id = {
16: Advapi32Const.CALG_AES_128,
24: Advapi32Const.CALG_AES_192,
32: Advapi32Const.CALG_AES_256,
}[len(key)]
else:
algorithm_id = {
'des': Advapi32Const.CALG_DES,
'tripledes_2key': Advapi32Const.CALG_3DES_112,
'tripledes_3key': Advapi32Const.CALG_3DES,
'rc2': Advapi32Const.CALG_RC2,
'rc4': Advapi32Const.CALG_RC4,
}[cipher]
provider = Advapi32Const.MS_ENH_RSA_AES_PROV
context_handle = open_context_handle(provider, verify_only=False)
blob_header_pointer = struct(advapi32, 'BLOBHEADER')
blob_header = unwrap(blob_header_pointer)
blob_header.bType = Advapi32Const.PLAINTEXTKEYBLOB
blob_header.bVersion = Advapi32Const.CUR_BLOB_VERSION
blob_header.reserved = 0
blob_header.aiKeyAlg = algorithm_id
blob_struct_pointer = struct(advapi32, 'PLAINTEXTKEYBLOB')
blob_struct = unwrap(blob_struct_pointer)
blob_struct.hdr = blob_header
blob_struct.dwKeySize = len(key)
blob = struct_bytes(blob_struct_pointer) + key
flags = 0
if cipher in set(['rc2', 'rc4']) and len(key) == 5:
flags = Advapi32Const.CRYPT_NO_SALT
key_handle_pointer = new(advapi32, 'HCRYPTKEY *')
res = advapi32.CryptImportKey(
context_handle,
blob,
len(blob),
null(),
flags,
key_handle_pointer
)
handle_error(res)
key_handle = unwrap(key_handle_pointer)
if cipher == 'rc2':
buf = new(advapi32, 'DWORD *', len(key) * 8)
res = advapi32.CryptSetKeyParam(
key_handle,
Advapi32Const.KP_EFFECTIVE_KEYLEN,
buf,
0
)
handle_error(res)
if cipher != 'rc4':
res = advapi32.CryptSetKeyParam(
key_handle,
Advapi32Const.KP_IV,
iv,
0
)
handle_error(res)
buf = new(advapi32, 'DWORD *', Advapi32Const.CRYPT_MODE_CBC)
res = advapi32.CryptSetKeyParam(
key_handle,
Advapi32Const.KP_MODE,
buf,
0
)
handle_error(res)
buf = new(advapi32, 'DWORD *', Advapi32Const.PKCS5_PADDING)
res = advapi32.CryptSetKeyParam(
key_handle,
Advapi32Const.KP_PADDING,
buf,
0
)
handle_error(res)
return (context_handle, key_handle)
def _bcrypt_create_key_handle(cipher, key):
"""
Creates a BCRYPT_KEY_HANDLE for symmetric encryption/decryption. The
handle must be released by bcrypt.BCryptDestroyKey() when done.
:param cipher:
A unicode string of "aes", "des", "tripledes_2key", "tripledes_3key",
"rc2", "rc4"
:param key:
A byte string of the symmetric key
:return:
A BCRYPT_KEY_HANDLE
"""
alg_handle = None
alg_constant = {
'aes': BcryptConst.BCRYPT_AES_ALGORITHM,
'des': BcryptConst.BCRYPT_DES_ALGORITHM,
'tripledes_2key': BcryptConst.BCRYPT_3DES_112_ALGORITHM,
'tripledes_3key': BcryptConst.BCRYPT_3DES_ALGORITHM,
'rc2': BcryptConst.BCRYPT_RC2_ALGORITHM,
'rc4': BcryptConst.BCRYPT_RC4_ALGORITHM,
}[cipher]
try:
alg_handle = open_alg_handle(alg_constant)
blob_type = BcryptConst.BCRYPT_KEY_DATA_BLOB
blob_struct_pointer = struct(bcrypt, 'BCRYPT_KEY_DATA_BLOB_HEADER')
blob_struct = unwrap(blob_struct_pointer)
blob_struct.dwMagic = BcryptConst.BCRYPT_KEY_DATA_BLOB_MAGIC
blob_struct.dwVersion = BcryptConst.BCRYPT_KEY_DATA_BLOB_VERSION1
blob_struct.cbKeyData = len(key)
blob = struct_bytes(blob_struct_pointer) + key
if cipher == 'rc2':
buf = new(bcrypt, 'DWORD *', len(key) * 8)
res = bcrypt.BCryptSetProperty(
alg_handle,
BcryptConst.BCRYPT_EFFECTIVE_KEY_LENGTH,
buf,
4,
0
)
handle_error(res)
key_handle_pointer = new(bcrypt, 'BCRYPT_KEY_HANDLE *')
res = bcrypt.BCryptImportKey(
alg_handle,
null(),
blob_type,
key_handle_pointer,
null(),
0,
blob,
len(blob),
0
)
handle_error(res)
return unwrap(key_handle_pointer)
finally:
if alg_handle:
close_alg_handle(alg_handle)
def _encrypt(cipher, key, data, iv, padding):
"""
Encrypts plaintext
:param cipher:
A unicode string of "aes", "des", "tripledes_2key", "tripledes_3key",
"rc2", "rc4"
:param key:
The encryption key - a byte string 5-16 bytes long
:param data:
The plaintext - a byte string
:param iv:
The initialization vector - a byte string - unused for RC4
:param padding:
Boolean, if padding should be used - unused for RC4
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the ciphertext
"""
if not isinstance(key, byte_cls):
raise TypeError(pretty_message(
'''
key must be a byte string, not %s
''',
type_name(key)
))
if not isinstance(data, byte_cls):
raise TypeError(pretty_message(
'''
data must be a byte string, not %s
''',
type_name(data)
))
if cipher != 'rc4' and not isinstance(iv, byte_cls):
raise TypeError(pretty_message(
'''
iv must be a byte string, not %s
''',
type_name(iv)
))
if cipher != 'rc4' and not padding:
# AES in CBC mode can be allowed with no padding if
# the data is an exact multiple of the block size
if not (cipher == 'aes' and len(data) % 16 == 0):
raise ValueError('padding must be specified')
if _backend == 'winlegacy':
return _advapi32_encrypt(cipher, key, data, iv, padding)
return _bcrypt_encrypt(cipher, key, data, iv, padding)
def _advapi32_encrypt(cipher, key, data, iv, padding):
"""
Encrypts plaintext via CryptoAPI
:param cipher:
A unicode string of "aes", "des", "tripledes_2key", "tripledes_3key",
"rc2", "rc4"
:param key:
The encryption key - a byte string 5-16 bytes long
:param data:
The plaintext - a byte string
:param iv:
The initialization vector - a byte string - unused for RC4
:param padding:
Boolean, if padding should be used - unused for RC4
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the ciphertext
"""
context_handle = None
key_handle = None
try:
context_handle, key_handle = _advapi32_create_handles(cipher, key, iv)
out_len = new(advapi32, 'DWORD *', len(data))
res = advapi32.CryptEncrypt(
key_handle,
null(),
True,
0,
null(),
out_len,
0
)
handle_error(res)
buffer_len = deref(out_len)
buffer = buffer_from_bytes(buffer_len)
write_to_buffer(buffer, data)
pointer_set(out_len, len(data))
res = advapi32.CryptEncrypt(
key_handle,
null(),
True,
0,
buffer,
out_len,
buffer_len
)
handle_error(res)
output = bytes_from_buffer(buffer, deref(out_len))
# Remove padding when not required. CryptoAPI doesn't support this, so
# we just manually remove it.
if cipher == 'aes' and not padding and len(output) == len(data) + 16:
output = output[:-16]
return output
finally:
if key_handle:
advapi32.CryptDestroyKey(key_handle)
if context_handle:
close_context_handle(context_handle)
def _bcrypt_encrypt(cipher, key, data, iv, padding):
"""
Encrypts plaintext via CNG
:param cipher:
A unicode string of "aes", "des", "tripledes_2key", "tripledes_3key",
"rc2", "rc4"
:param key:
The encryption key - a byte string 5-16 bytes long
:param data:
The plaintext - a byte string
:param iv:
The initialization vector - a byte string - unused for RC4
:param padding:
Boolean, if padding should be used - unused for RC4
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the ciphertext
"""
key_handle = None
try:
key_handle = _bcrypt_create_key_handle(cipher, key)
if iv is None:
iv_len = 0
else:
iv_len = len(iv)
flags = 0
if padding is True:
flags = BcryptConst.BCRYPT_BLOCK_PADDING
out_len = new(bcrypt, 'ULONG *')
res = bcrypt.BCryptEncrypt(
key_handle,
data,
len(data),
null(),
null(),
0,
null(),
0,
out_len,
flags
)
handle_error(res)
buffer_len = deref(out_len)
buffer = buffer_from_bytes(buffer_len)
iv_buffer = buffer_from_bytes(iv) if iv else null()
res = bcrypt.BCryptEncrypt(
key_handle,
data,
len(data),
null(),
iv_buffer,
iv_len,
buffer,
buffer_len,
out_len,
flags
)
handle_error(res)
return bytes_from_buffer(buffer, deref(out_len))
finally:
if key_handle:
bcrypt.BCryptDestroyKey(key_handle)
def _decrypt(cipher, key, data, iv, padding):
"""
Decrypts AES/RC4/RC2/3DES/DES ciphertext
:param cipher:
A unicode string of "aes", "des", "tripledes_2key", "tripledes_3key",
"rc2", "rc4"
:param key:
The encryption key - a byte string 5-16 bytes long
:param data:
The ciphertext - a byte string
:param iv:
The initialization vector - a byte string - unused for RC4
:param padding:
Boolean, if padding should be used - unused for RC4
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the plaintext
"""
if not isinstance(key, byte_cls):
raise TypeError(pretty_message(
'''
key must be a byte string, not %s
''',
type_name(key)
))
if not isinstance(data, byte_cls):
raise TypeError(pretty_message(
'''
data must be a byte string, not %s
''',
type_name(data)
))
if cipher != 'rc4' and not isinstance(iv, byte_cls):
raise TypeError(pretty_message(
'''
iv must be a byte string, not %s
''',
type_name(iv)
))
if cipher not in set(['rc4', 'aes']) and not padding:
raise ValueError('padding must be specified')
if _backend == 'winlegacy':
return _advapi32_decrypt(cipher, key, data, iv, padding)
return _bcrypt_decrypt(cipher, key, data, iv, padding)
def _advapi32_decrypt(cipher, key, data, iv, padding):
"""
Decrypts AES/RC4/RC2/3DES/DES ciphertext via CryptoAPI
:param cipher:
A unicode string of "aes", "des", "tripledes_2key", "tripledes_3key",
"rc2", "rc4"
:param key:
The encryption key - a byte string 5-16 bytes long
:param data:
The ciphertext - a byte string
:param iv:
The initialization vector - a byte string - unused for RC4
:param padding:
Boolean, if padding should be used - unused for RC4
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the plaintext
"""
context_handle = None
key_handle = None
try:
context_handle, key_handle = _advapi32_create_handles(cipher, key, iv)
if cipher == 'aes' and not padding and len(data) % 16 != 0:
raise ValueError('Invalid data - ciphertext length must be a multiple of 16')
buffer = buffer_from_bytes(data)
out_len = new(advapi32, 'DWORD *', len(data))
res = advapi32.CryptDecrypt(
key_handle,
null(),
# To skip padding, we have to tell the API that this is not
# the final block
False if cipher == 'aes' and not padding else True,
0,
buffer,
out_len
)
handle_error(res)
return bytes_from_buffer(buffer, deref(out_len))
finally:
if key_handle:
advapi32.CryptDestroyKey(key_handle)
if context_handle:
close_context_handle(context_handle)
def _bcrypt_decrypt(cipher, key, data, iv, padding):
"""
Decrypts AES/RC4/RC2/3DES/DES ciphertext via CNG
:param cipher:
A unicode string of "aes", "des", "tripledes_2key", "tripledes_3key",
"rc2", "rc4"
:param key:
The encryption key - a byte string 5-16 bytes long
:param data:
The ciphertext - a byte string
:param iv:
The initialization vector - a byte string - unused for RC4
:param padding:
Boolean, if padding should be used - unused for RC4
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by the OS crypto library
:return:
A byte string of the plaintext
"""
key_handle = None
try:
key_handle = _bcrypt_create_key_handle(cipher, key)
if iv is None:
iv_len = 0
else:
iv_len = len(iv)
flags = 0
if padding is True:
flags = BcryptConst.BCRYPT_BLOCK_PADDING
out_len = new(bcrypt, 'ULONG *')
res = bcrypt.BCryptDecrypt(
key_handle,
data,
len(data),
null(),
null(),
0,
null(),
0,
out_len,
flags
)
handle_error(res)
buffer_len = deref(out_len)
buffer = buffer_from_bytes(buffer_len)
iv_buffer = buffer_from_bytes(iv) if iv else null()
res = bcrypt.BCryptDecrypt(
key_handle,
data,
len(data),
null(),
iv_buffer,
iv_len,
buffer,
buffer_len,
out_len,
flags
)
handle_error(res)
return bytes_from_buffer(buffer, deref(out_len))
finally:
if key_handle:
bcrypt.BCryptDestroyKey(key_handle)
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