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| # -*- coding: utf-8 -*- | |
| # | |
| # Cipher/DES3.py : DES3 | |
| # | |
| # =================================================================== | |
| # The contents of this file are dedicated to the public domain. To | |
| # the extent that dedication to the public domain is not available, | |
| # everyone is granted a worldwide, perpetual, royalty-free, | |
| # non-exclusive license to exercise all rights associated with the | |
| # contents of this file for any purpose whatsoever. | |
| # No rights are reserved. | |
| # | |
| # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | |
| # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF | |
| # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | |
| # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS | |
| # BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN | |
| # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN | |
| # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
| # SOFTWARE. | |
| # =================================================================== | |
| """ | |
| Module's constants for the modes of operation supported with Triple DES: | |
| :var MODE_ECB: :ref:`Electronic Code Book (ECB) <ecb_mode>` | |
| :var MODE_CBC: :ref:`Cipher-Block Chaining (CBC) <cbc_mode>` | |
| :var MODE_CFB: :ref:`Cipher FeedBack (CFB) <cfb_mode>` | |
| :var MODE_OFB: :ref:`Output FeedBack (OFB) <ofb_mode>` | |
| :var MODE_CTR: :ref:`CounTer Mode (CTR) <ctr_mode>` | |
| :var MODE_OPENPGP: :ref:`OpenPGP Mode <openpgp_mode>` | |
| :var MODE_EAX: :ref:`EAX Mode <eax_mode>` | |
| """ | |
| import sys | |
| from Crypto.Cipher import _create_cipher | |
| from Crypto.Util.py3compat import byte_string, bchr, bord, bstr | |
| from Crypto.Util._raw_api import (load_pycryptodome_raw_lib, | |
| VoidPointer, SmartPointer, | |
| c_size_t) | |
| _raw_des3_lib = load_pycryptodome_raw_lib( | |
| "Crypto.Cipher._raw_des3", | |
| """ | |
| int DES3_start_operation(const uint8_t key[], | |
| size_t key_len, | |
| void **pResult); | |
| int DES3_encrypt(const void *state, | |
| const uint8_t *in, | |
| uint8_t *out, | |
| size_t data_len); | |
| int DES3_decrypt(const void *state, | |
| const uint8_t *in, | |
| uint8_t *out, | |
| size_t data_len); | |
| int DES3_stop_operation(void *state); | |
| """) | |
| def adjust_key_parity(key_in): | |
| """Set the parity bits in a TDES key. | |
| :param key_in: the TDES key whose bits need to be adjusted | |
| :type key_in: byte string | |
| :returns: a copy of ``key_in``, with the parity bits correctly set | |
| :rtype: byte string | |
| :raises ValueError: if the TDES key is not 16 or 24 bytes long | |
| :raises ValueError: if the TDES key degenerates into Single DES | |
| """ | |
| def parity_byte(key_byte): | |
| parity = 1 | |
| for i in range(1, 8): | |
| parity ^= (key_byte >> i) & 1 | |
| return (key_byte & 0xFE) | parity | |
| if len(key_in) not in key_size: | |
| raise ValueError("Not a valid TDES key") | |
| key_out = b"".join([ bchr(parity_byte(bord(x))) for x in key_in ]) | |
| if key_out[:8] == key_out[8:16] or key_out[-16:-8] == key_out[-8:]: | |
| raise ValueError("Triple DES key degenerates to single DES") | |
| return key_out | |
| def _create_base_cipher(dict_parameters): | |
| """This method instantiates and returns a handle to a low-level base cipher. | |
| It will absorb named parameters in the process.""" | |
| try: | |
| key_in = dict_parameters.pop("key") | |
| except KeyError: | |
| raise TypeError("Missing 'key' parameter") | |
| key = adjust_key_parity(bstr(key_in)) | |
| start_operation = _raw_des3_lib.DES3_start_operation | |
| stop_operation = _raw_des3_lib.DES3_stop_operation | |
| cipher = VoidPointer() | |
| result = start_operation(key, | |
| c_size_t(len(key)), | |
| cipher.address_of()) | |
| if result: | |
| raise ValueError("Error %X while instantiating the TDES cipher" | |
| % result) | |
| return SmartPointer(cipher.get(), stop_operation) | |
| def new(key, mode, *args, **kwargs): | |
| """Create a new Triple DES cipher. | |
| :param key: | |
| The secret key to use in the symmetric cipher. | |
| It must be 16 or 24 byte long. The parity bits will be ignored. | |
| :type key: bytes/bytearray/memoryview | |
| :param mode: | |
| The chaining mode to use for encryption or decryption. | |
| :type mode: One of the supported ``MODE_*`` constants | |
| :Keyword Arguments: | |
| * **iv** (*bytes*, *bytearray*, *memoryview*) -- | |
| (Only applicable for ``MODE_CBC``, ``MODE_CFB``, ``MODE_OFB``, | |
| and ``MODE_OPENPGP`` modes). | |
| The initialization vector to use for encryption or decryption. | |
| For ``MODE_CBC``, ``MODE_CFB``, and ``MODE_OFB`` it must be 8 bytes long. | |
| For ``MODE_OPENPGP`` mode only, | |
| it must be 8 bytes long for encryption | |
| and 10 bytes for decryption (in the latter case, it is | |
| actually the *encrypted* IV which was prefixed to the ciphertext). | |
| If not provided, a random byte string is generated (you must then | |
| read its value with the :attr:`iv` attribute). | |
| * **nonce** (*bytes*, *bytearray*, *memoryview*) -- | |
| (Only applicable for ``MODE_EAX`` and ``MODE_CTR``). | |
| A value that must never be reused for any other encryption done | |
| with this key. | |
| For ``MODE_EAX`` there are no | |
| restrictions on its length (recommended: **16** bytes). | |
| For ``MODE_CTR``, its length must be in the range **[0..7]**. | |
| If not provided for ``MODE_EAX``, a random byte string is generated (you | |
| can read it back via the ``nonce`` attribute). | |
| * **segment_size** (*integer*) -- | |
| (Only ``MODE_CFB``).The number of **bits** the plaintext and ciphertext | |
| are segmented in. It must be a multiple of 8. | |
| If not specified, it will be assumed to be 8. | |
| * **mac_len** : (*integer*) -- | |
| (Only ``MODE_EAX``) | |
| Length of the authentication tag, in bytes. | |
| It must be no longer than 8 (default). | |
| * **initial_value** : (*integer*) -- | |
| (Only ``MODE_CTR``). The initial value for the counter within | |
| the counter block. By default it is **0**. | |
| :Return: a Triple DES object, of the applicable mode. | |
| """ | |
| return _create_cipher(sys.modules[__name__], key, mode, *args, **kwargs) | |
| MODE_ECB = 1 | |
| MODE_CBC = 2 | |
| MODE_CFB = 3 | |
| MODE_OFB = 5 | |
| MODE_CTR = 6 | |
| MODE_OPENPGP = 7 | |
| MODE_EAX = 9 | |
| # Size of a data block (in bytes) | |
| block_size = 8 | |
| # Size of a key (in bytes) | |
| key_size = (16, 24) | |