219 lines
8 KiB
Python
219 lines
8 KiB
Python
|
# -*- coding: utf-8 -*-
|
||
|
#
|
||
|
# Cipher/ARC2.py : ARC2.py
|
||
|
#
|
||
|
# ===================================================================
|
||
|
# 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.
|
||
|
# ===================================================================
|
||
|
"""RC2 symmetric cipher
|
||
|
|
||
|
RC2_ (Rivest's Cipher version 2) is a symmetric block cipher designed
|
||
|
by Ron Rivest in 1987. The cipher started as a proprietary design,
|
||
|
that was reverse engineered and anonymously posted on Usenet in 1996.
|
||
|
For this reason, the algorithm was first called *Alleged* RC2 (ARC2),
|
||
|
since the company that owned RC2 (RSA Data Inc.) did not confirm whether
|
||
|
the details leaked into public domain were really correct.
|
||
|
|
||
|
The company eventually published its full specification in RFC2268_.
|
||
|
|
||
|
RC2 has a fixed data block size of 8 bytes. Length of its keys can vary from
|
||
|
8 to 128 bits. One particular property of RC2 is that the actual
|
||
|
cryptographic strength of the key (*effective key length*) can be reduced
|
||
|
via a parameter.
|
||
|
|
||
|
Even though RC2 is not cryptographically broken, it has not been analyzed as
|
||
|
thoroughly as AES, which is also faster than RC2.
|
||
|
|
||
|
**Use AES, not ARC2. This module is only provided for legacy purposes.**
|
||
|
|
||
|
As an example, encryption can be done as follows:
|
||
|
|
||
|
>>> from Crypto.Cipher import ARC2
|
||
|
>>>
|
||
|
>>> key = b'Sixteen byte key'
|
||
|
>>> cipher = ARC2.new(key, ARC2.MODE_CFB)
|
||
|
>>> msg = cipher.iv + cipher.encrypt(b'Attack at dawn')
|
||
|
|
||
|
.. _RC2: http://en.wikipedia.org/wiki/RC2
|
||
|
.. _RFC2268: http://tools.ietf.org/html/rfc2268
|
||
|
|
||
|
:undocumented: __package__
|
||
|
"""
|
||
|
|
||
|
import sys
|
||
|
|
||
|
from Crypto.Cipher import _create_cipher
|
||
|
from Crypto.Util.py3compat import byte_string
|
||
|
from Crypto.Util._raw_api import (load_pycryptodome_raw_lib,
|
||
|
VoidPointer, SmartPointer,
|
||
|
c_size_t, expect_byte_string)
|
||
|
|
||
|
_raw_arc2_lib = load_pycryptodome_raw_lib(
|
||
|
"Crypto.Cipher._raw_arc2",
|
||
|
"""
|
||
|
int ARC2_start_operation(const uint8_t key[],
|
||
|
size_t key_len,
|
||
|
size_t effective_key_len,
|
||
|
void **pResult);
|
||
|
int ARC2_encrypt(const void *state,
|
||
|
const uint8_t *in,
|
||
|
uint8_t *out,
|
||
|
size_t data_len);
|
||
|
int ARC2_decrypt(const void *state,
|
||
|
const uint8_t *in,
|
||
|
uint8_t *out,
|
||
|
size_t data_len);
|
||
|
int ARC2_stop_operation(void *state);
|
||
|
"""
|
||
|
)
|
||
|
|
||
|
|
||
|
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 = dict_parameters.pop("key")
|
||
|
except KeyError:
|
||
|
raise TypeError("Missing 'key' parameter")
|
||
|
|
||
|
effective_keylen = dict_parameters.pop("effective_keylen", 1024)
|
||
|
|
||
|
expect_byte_string(key)
|
||
|
|
||
|
if len(key) not in key_size:
|
||
|
raise ValueError("Incorrect ARC2 key length (%d bytes)" % len(key))
|
||
|
|
||
|
if not (40 < effective_keylen <= 1024):
|
||
|
raise ValueError("'effective_key_len' must be no larger than 1024 "
|
||
|
"(not %d)" % effective_keylen)
|
||
|
|
||
|
start_operation = _raw_arc2_lib.ARC2_start_operation
|
||
|
stop_operation = _raw_arc2_lib.ARC2_stop_operation
|
||
|
|
||
|
cipher = VoidPointer()
|
||
|
result = start_operation(key,
|
||
|
c_size_t(len(key)),
|
||
|
c_size_t(effective_keylen),
|
||
|
cipher.address_of())
|
||
|
if result:
|
||
|
raise ValueError("Error %X while instantiating the ARC2 cipher"
|
||
|
% result)
|
||
|
|
||
|
return SmartPointer(cipher.get(), stop_operation)
|
||
|
|
||
|
|
||
|
def new(key, mode, *args, **kwargs):
|
||
|
"""Create a new RC2 cipher
|
||
|
|
||
|
:Parameters:
|
||
|
key : byte string
|
||
|
The secret key to use in the symmetric cipher.
|
||
|
Its length can vary from 5 to 128 bytes.
|
||
|
|
||
|
mode : a *MODE_** constant
|
||
|
The chaining mode to use for encryption or decryption.
|
||
|
|
||
|
:Keywords:
|
||
|
iv : byte string
|
||
|
(*Only* `MODE_CBC`, `MODE_CFB`, `MODE_OFB`, `MODE_OPENPGP`).
|
||
|
|
||
|
The initialization vector to use for encryption or decryption.
|
||
|
|
||
|
For `MODE_OPENPGP`, IV 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).
|
||
|
|
||
|
For all other modes, it must be 8 bytes long.
|
||
|
|
||
|
If not provided, a random byte string will be generated (you
|
||
|
must read it back via the ``iv`` attribute of the cipher).
|
||
|
|
||
|
nonce : byte string
|
||
|
(*Only* `MODE_EAX` and `MODE_CTR`).
|
||
|
A value that must never be reused for any other encryption done with
|
||
|
this key.
|
||
|
|
||
|
For `MODE_CTR`, its length must be in the range ``[0..7]``.
|
||
|
|
||
|
For `MODE_EAX`, there are no restrictions, but it is recommended to
|
||
|
use at least 16 bytes.
|
||
|
|
||
|
If not provided for `MODE_EAX`, a random byte string will be
|
||
|
generated (you must read it back via the ``nonce`` attribute
|
||
|
of the cipher).
|
||
|
|
||
|
mac_len : integer
|
||
|
(*Only* `MODE_EAX`). Length of the authentication tag, in bytes.
|
||
|
It must be no larger than 8 (which is the default).
|
||
|
|
||
|
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.
|
||
|
|
||
|
initial_value : integer
|
||
|
(*Only* `MODE_CTR`). The initial value for the counter within
|
||
|
the counter block. By default it is 0.
|
||
|
|
||
|
effective_keylen : integer
|
||
|
Maximum cryptographic strength of the key, in **bits**.
|
||
|
It can vary from 40 to 1024. The default value is 1024.
|
||
|
|
||
|
:Return: an RC2 cipher object, of the applicable mode:
|
||
|
|
||
|
- CBC_ mode
|
||
|
- CFB_ mode
|
||
|
- CTR_ mode
|
||
|
- EAX_ mode
|
||
|
- ECB_ mode
|
||
|
- OFB_ mode
|
||
|
- OpenPgp_ mode
|
||
|
|
||
|
.. _CBC: Crypto.Cipher._mode_cbc.CbcMode-class.html
|
||
|
.. _CFB: Crypto.Cipher._mode_cfb.CfbMode-class.html
|
||
|
.. _CTR: Crypto.Cipher._mode_ctr.CtrMode-class.html
|
||
|
.. _EAX: Crypto.Cipher._mode_eax.EaxMode-class.html
|
||
|
.. _ECB: Crypto.Cipher._mode_ecb.EcbMode-class.html
|
||
|
.. _OFB: Crypto.Cipher._mode_ofb.OfbMode-class.html
|
||
|
.. _OpenPgp: Crypto.Cipher._mode_openpgp.OpenPgpMode-class.html
|
||
|
|
||
|
"""
|
||
|
|
||
|
return _create_cipher(sys.modules[__name__], key, mode, *args, **kwargs)
|
||
|
|
||
|
#: Electronic Code Book (ECB). See `Crypto.Cipher._mode_ecb.EcbMode`.
|
||
|
MODE_ECB = 1
|
||
|
#: Cipher-Block Chaining (CBC). See `Crypto.Cipher._mode_cbc.CbcMode`.
|
||
|
MODE_CBC = 2
|
||
|
#: Cipher FeedBack (CFB). See `Crypto.Cipher._mode_cfb.CfbMode`.
|
||
|
MODE_CFB = 3
|
||
|
#: Output FeedBack (OFB). See `Crypto.Cipher._mode_ofb.OfbMode`.
|
||
|
MODE_OFB = 5
|
||
|
#: CounTer Mode (CTR). See `Crypto.Cipher._mode_ctr.CtrMode`.
|
||
|
MODE_CTR = 6
|
||
|
#: OpenPGP Mode. See `Crypto.Cipher._mode_openpgp.OpenPgpMode`.
|
||
|
MODE_OPENPGP = 7
|
||
|
#: EAX Mode. See `Crypto.Cipher._mode_eax.EaxMode`.
|
||
|
MODE_EAX = 9
|
||
|
|
||
|
#: Size of a data block (in bytes)
|
||
|
block_size = 8
|
||
|
#: Size of a key (in bytes)
|
||
|
key_size = range(5, 128 + 1)
|