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Diffstat (limited to 'frozen_deps/Crypto/Cipher/ARC2.py')
| -rw-r--r-- | frozen_deps/Crypto/Cipher/ARC2.py | 130 |
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diff --git a/frozen_deps/Crypto/Cipher/ARC2.py b/frozen_deps/Crypto/Cipher/ARC2.py new file mode 100644 index 0000000..b5234e6 --- /dev/null +++ b/frozen_deps/Crypto/Cipher/ARC2.py @@ -0,0 +1,130 @@ +# -*- 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. + +New designs should not use RC2. + +As an example, encryption can be done as follows: + + >>> from Crypto.Cipher import ARC2 + >>> from Crypto import Random + >>> + >>> key = b'Sixteen byte key' + >>> iv = Random.new().read(ARC2.block_size) + >>> cipher = ARC2.new(key, ARC2.MODE_CFB, iv) + >>> msg = iv + cipher.encrypt(b'Attack at dawn') + +.. _RC2: http://en.wikipedia.org/wiki/RC2 +.. _RFC2268: http://tools.ietf.org/html/rfc2268 + +:undocumented: __revision__, __package__ +""" + +__revision__ = "$Id$" + +from Crypto.Cipher import blockalgo +from Crypto.Cipher import _ARC2 + +class RC2Cipher (blockalgo.BlockAlgo): + """RC2 cipher object""" + + def __init__(self, key, *args, **kwargs): + """Initialize an ARC2 cipher object + + See also `new()` at the module level.""" + blockalgo.BlockAlgo.__init__(self, _ARC2, key, *args, **kwargs) + +def new(key, *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 1 to 128 bytes. + :Keywords: + mode : a *MODE_** constant + The chaining mode to use for encryption or decryption. + Default is `MODE_ECB`. + IV : byte string + The initialization vector to use for encryption or decryption. + + It is ignored for `MODE_ECB` and `MODE_CTR`. + + For `MODE_OPENPGP`, IV must be `block_size` bytes long for encryption + and `block_size` +2 bytes for decryption (in the latter case, it is + actually the *encrypted* IV which was prefixed to the ciphertext). + It is mandatory. + + For all other modes, it must be `block_size` bytes longs. It is optional and + when not present it will be given a default value of all zeroes. + counter : callable + (*Only* `MODE_CTR`). A stateful function that returns the next + *counter block*, which is a byte string of `block_size` bytes. + For better performance, use `Crypto.Util.Counter`. + 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 0 or not specified, it will be assumed to be 8. + effective_keylen : integer + Maximum cryptographic strength of the key, in bits. + It can vary from 0 to 1024. The default value is 1024. + + :Return: an `RC2Cipher` object + """ + return RC2Cipher(key, *args, **kwargs) + +#: Electronic Code Book (ECB). See `blockalgo.MODE_ECB`. +MODE_ECB = 1 +#: Cipher-Block Chaining (CBC). See `blockalgo.MODE_CBC`. +MODE_CBC = 2 +#: Cipher FeedBack (CFB). See `blockalgo.MODE_CFB`. +MODE_CFB = 3 +#: This mode should not be used. +MODE_PGP = 4 +#: Output FeedBack (OFB). See `blockalgo.MODE_OFB`. +MODE_OFB = 5 +#: CounTer Mode (CTR). See `blockalgo.MODE_CTR`. +MODE_CTR = 6 +#: OpenPGP Mode. See `blockalgo.MODE_OPENPGP`. +MODE_OPENPGP = 7 +#: Size of a data block (in bytes) +block_size = 8 +#: Size of a key (in bytes) +key_size = range(1,16+1) + |