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Diffstat (limited to 'frozen_deps/Crypto/Cipher/DES3.py')
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diff --git a/frozen_deps/Crypto/Cipher/DES3.py b/frozen_deps/Crypto/Cipher/DES3.py new file mode 100644 index 0000000..7fedac8 --- /dev/null +++ b/frozen_deps/Crypto/Cipher/DES3.py @@ -0,0 +1,133 @@ +# -*- 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. +# =================================================================== +"""Triple DES symmetric cipher + +`Triple DES`__ (or TDES or TDEA or 3DES) is a symmetric block cipher standardized by NIST_. +It has a fixed data block size of 8 bytes. Its keys are 128 (*Option 1*) or 192 +bits (*Option 2*) long. +However, 1 out of 8 bits is used for redundancy and do not contribute to +security. The effective key length is respectively 112 or 168 bits. + +TDES consists of the concatenation of 3 simple `DES` ciphers. + +The plaintext is first DES encrypted with *K1*, then decrypted with *K2*, +and finally encrypted again with *K3*. The ciphertext is decrypted in the reverse manner. + +The 192 bit key is a bundle of three 64 bit independent subkeys: *K1*, *K2*, and *K3*. + +The 128 bit key is split into *K1* and *K2*, whereas *K1=K3*. + +It is important that all subkeys are different, otherwise TDES would degrade to +single `DES`. + +TDES is cryptographically secure, even though it is neither as secure nor as fast +as `AES`. + +As an example, encryption can be done as follows: + + >>> from Crypto.Cipher import DES + >>> from Crypto import Random + >>> from Crypto.Util import Counter + >>> + >>> key = b'-8B key-' + >>> nonce = Random.new().read(DES.block_size/2) + >>> ctr = Counter.new(DES.block_size*8/2, prefix=nonce) + >>> cipher = DES.new(key, DES.MODE_CTR, counter=ctr) + >>> plaintext = b'We are no longer the knights who say ni!' + >>> msg = nonce + cipher.encrypt(plaintext) + +.. __: http://en.wikipedia.org/wiki/Triple_DES +.. _NIST: http://csrc.nist.gov/publications/nistpubs/800-67/SP800-67.pdf + +:undocumented: __revision__, __package__ +""" + +__revision__ = "$Id$" + +from Crypto.Cipher import blockalgo +from Crypto.Cipher import _DES3 + +class DES3Cipher(blockalgo.BlockAlgo): + """TDES cipher object""" + + def __init__(self, key, *args, **kwargs): + """Initialize a TDES cipher object + + See also `new()` at the module level.""" + blockalgo.BlockAlgo.__init__(self, _DES3, key, *args, **kwargs) + +def new(key, *args, **kwargs): + """Create a new TDES cipher + + :Parameters: + key : byte string + The secret key to use in the symmetric cipher. + It must be 16 or 24 bytes long. The parity bits will be ignored. + :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. + + :Attention: it is important that all 8 byte subkeys are different, + otherwise TDES would degrade to single `DES`. + :Return: an `DES3Cipher` object + """ + return DES3Cipher(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 = ( 16, 24 ) |