/Contents/Libraries/Shared/Crypto/Cipher/Blowfish.py
Python | 121 lines | 83 code | 0 blank | 38 comment | 0 complexity | a05c42d802329888ac6f5391ab223360 MD5 | raw file
- # -*- coding: utf-8 -*-
- #
- # Cipher/Blowfish.py : Blowfish
- #
- # ===================================================================
- # 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.
- # ===================================================================
- """Blowfish symmetric cipher
- Blowfish_ is a symmetric block cipher designed by Bruce Schneier.
- It has a fixed data block size of 8 bytes and its keys can vary in length
- from 32 to 448 bits (4 to 56 bytes).
- Blowfish is deemed secure and it is fast. However, its keys should be chosen
- to be big enough to withstand a brute force attack (e.g. at least 16 bytes).
- As an example, encryption can be done as follows:
- >>> from Crypto.Cipher import Blowfish
- >>> from Crypto import Random
- >>> from struct import pack
- >>>
- >>> bs = Blowfish.block_size
- >>> key = b'An arbitrarily long key'
- >>> iv = Random.new().read(bs)
- >>> cipher = Blowfish.new(key, Blowfish.MODE_CBC, iv)
- >>> plaintext = b'docendo discimus '
- >>> plen = bs - divmod(len(plaintext),bs)[1]
- >>> padding = [plen]*plen
- >>> padding = pack('b'*plen, *padding)
- >>> msg = iv + cipher.encrypt(plaintext + padding)
- .. _Blowfish: http://www.schneier.com/blowfish.html
- :undocumented: __revision__, __package__
- """
- __revision__ = "$Id$"
- from Crypto.Cipher import blockalgo
- from Crypto.Cipher import _Blowfish
- class BlowfishCipher (blockalgo.BlockAlgo):
- """Blowfish cipher object"""
- def __init__(self, key, *args, **kwargs):
- """Initialize a Blowfish cipher object
-
- See also `new()` at the module level."""
- blockalgo.BlockAlgo.__init__(self, _Blowfish, key, *args, **kwargs)
- def new(key, *args, **kwargs):
- """Create a new Blowfish cipher
- :Parameters:
- key : byte string
- The secret key to use in the symmetric cipher.
- Its length can vary from 4 to 56 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.
- :Return: a `BlowfishCipher` object
- """
- return BlowfishCipher(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 = xrange(4,56+1)