folder reorganization
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cttynul
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# -*- coding: ascii -*-
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#
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# Util/Counter.py : Fast counter for use with CTR-mode ciphers
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#
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# Written in 2008 by Dwayne C. Litzenberger <dlitz@dlitz.net>
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#
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# ===================================================================
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# The contents of this file are dedicated to the public domain. To
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# the extent that dedication to the public domain is not available,
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# everyone is granted a worldwide, perpetual, royalty-free,
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# non-exclusive license to exercise all rights associated with the
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# contents of this file for any purpose whatsoever.
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# No rights are reserved.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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# ===================================================================
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"""Fast counter functions for CTR cipher modes.
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CTR is a chaining mode for symmetric block encryption or decryption.
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Messages are divideded into blocks, and the cipher operation takes
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place on each block using the secret key and a unique *counter block*.
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The most straightforward way to fulfil the uniqueness property is
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to start with an initial, random *counter block* value, and increment it as
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the next block is processed.
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The block ciphers from `Crypto.Cipher` (when configured in *MODE_CTR* mode)
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invoke a callable object (the *counter* parameter) to get the next *counter block*.
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Unfortunately, the Python calling protocol leads to major performance degradations.
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The counter functions instantiated by this module will be invoked directly
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by the ciphers in `Crypto.Cipher`. The fact that the Python layer is bypassed
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lead to more efficient (and faster) execution of CTR cipher modes.
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An example of usage is the following:
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>>> from Crypto.Cipher import AES
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>>> from Crypto.Util import Counter
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>>>
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>>> pt = b'\x00'*1000000
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>>> ctr = Counter.new(128)
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>>> cipher = AES.new(b'\x00'*16, AES.MODE_CTR, counter=ctr)
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>>> ct = cipher.encrypt(pt)
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:undocumented: __package__
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"""
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import sys
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if sys.version_info[0] == 2 and sys.version_info[1] == 1:
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from Crypto.Util.py21compat import *
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from Crypto.Util.py3compat import *
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from Crypto.Util import _counter
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import struct
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# Factory function
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def new(nbits, prefix=b(""), suffix=b(""), initial_value=1, overflow=0, little_endian=False, allow_wraparound=False, disable_shortcut=False):
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"""Create a stateful counter block function suitable for CTR encryption modes.
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Each call to the function returns the next counter block.
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Each counter block is made up by three parts::
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prefix || counter value || postfix
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The counter value is incremented by one at each call.
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:Parameters:
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nbits : integer
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Length of the desired counter, in bits. It must be a multiple of 8.
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prefix : byte string
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The constant prefix of the counter block. By default, no prefix is
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used.
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suffix : byte string
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The constant postfix of the counter block. By default, no suffix is
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used.
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initial_value : integer
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The initial value of the counter. Default value is 1.
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little_endian : boolean
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If True, the counter number will be encoded in little endian format.
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If False (default), in big endian format.
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allow_wraparound : boolean
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If True, the function will raise an *OverflowError* exception as soon
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as the counter wraps around. If False (default), the counter will
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simply restart from zero.
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disable_shortcut : boolean
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If True, do not make ciphers from `Crypto.Cipher` bypass the Python
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layer when invoking the counter block function.
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If False (default), bypass the Python layer.
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:Returns:
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The counter block function.
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"""
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# Sanity-check the message size
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(nbytes, remainder) = divmod(nbits, 8)
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if remainder != 0:
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# In the future, we might support arbitrary bit lengths, but for now we don't.
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raise ValueError("nbits must be a multiple of 8; got %d" % (nbits,))
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if nbytes < 1:
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raise ValueError("nbits too small")
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elif nbytes > 0xffff:
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raise ValueError("nbits too large")
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initval = _encode(initial_value, nbytes, little_endian)
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if little_endian:
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return _counter._newLE(bstr(prefix), bstr(suffix), initval, allow_wraparound=allow_wraparound, disable_shortcut=disable_shortcut)
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else:
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return _counter._newBE(bstr(prefix), bstr(suffix), initval, allow_wraparound=allow_wraparound, disable_shortcut=disable_shortcut)
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def _encode(n, nbytes, little_endian=False):
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retval = []
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n = long(n)
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for i in range(nbytes):
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if little_endian:
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retval.append(bchr(n & 0xff))
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else:
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retval.insert(0, bchr(n & 0xff))
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n >>= 8
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return b("").join(retval)
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# vim:set ts=4 sw=4 sts=4 expandtab:
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@@ -0,0 +1,37 @@
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# -*- coding: utf-8 -*-
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#
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# ===================================================================
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# The contents of this file are dedicated to the public domain. To
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# the extent that dedication to the public domain is not available,
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# everyone is granted a worldwide, perpetual, royalty-free,
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# non-exclusive license to exercise all rights associated with the
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# contents of this file for any purpose whatsoever.
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# No rights are reserved.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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# ===================================================================
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"""Miscellaneous modules
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Contains useful modules that don't belong into any of the
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other Crypto.* subpackages.
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Crypto.Util.number Number-theoretic functions (primality testing, etc.)
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Crypto.Util.randpool Random number generation
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Crypto.Util.RFC1751 Converts between 128-bit keys and human-readable
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strings of words.
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Crypto.Util.asn1 Minimal support for ASN.1 DER encoding
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"""
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__all__ = ['randpool', 'RFC1751', 'number', 'strxor', 'asn1' ]
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__revision__ = "$Id$"
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Binary file not shown.
@@ -0,0 +1,107 @@
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# -*- coding: utf-8 -*-
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#
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# Util/py3compat.py : Compatibility code for handling Py3k / Python 2.x
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#
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# Written in 2010 by Thorsten Behrens
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#
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# ===================================================================
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# The contents of this file are dedicated to the public domain. To
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# the extent that dedication to the public domain is not available,
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# everyone is granted a worldwide, perpetual, royalty-free,
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# non-exclusive license to exercise all rights associated with the
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# contents of this file for any purpose whatsoever.
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# No rights are reserved.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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# ===================================================================
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"""Compatibility code for handling string/bytes changes from Python 2.x to Py3k
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In Python 2.x, strings (of type ''str'') contain binary data, including encoded
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Unicode text (e.g. UTF-8). The separate type ''unicode'' holds Unicode text.
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Unicode literals are specified via the u'...' prefix. Indexing or slicing
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either type always produces a string of the same type as the original.
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Data read from a file is always of '''str'' type.
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In Python 3.x, strings (type ''str'') may only contain Unicode text. The u'...'
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prefix and the ''unicode'' type are now redundant. A new type (called
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''bytes'') has to be used for binary data (including any particular
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''encoding'' of a string). The b'...' prefix allows one to specify a binary
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literal. Indexing or slicing a string produces another string. Slicing a byte
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string produces another byte string, but the indexing operation produces an
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integer. Data read from a file is of '''str'' type if the file was opened in
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text mode, or of ''bytes'' type otherwise.
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Since PyCrypto aims at supporting both Python 2.x and 3.x, the following helper
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functions are used to keep the rest of the library as independent as possible
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from the actual Python version.
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In general, the code should always deal with binary strings, and use integers
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instead of 1-byte character strings.
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b(s)
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Take a text string literal (with no prefix or with u'...' prefix) and
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make a byte string.
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bchr(c)
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Take an integer and make a 1-character byte string.
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bord(c)
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Take the result of indexing on a byte string and make an integer.
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tobytes(s)
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Take a text string, a byte string, or a sequence of character taken from
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a byte string and make a byte string.
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"""
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__revision__ = "$Id$"
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import sys
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if sys.version_info[0] == 2:
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def b(s):
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return s
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def bchr(s):
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return chr(s)
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def bstr(s):
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return str(s)
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def bord(s):
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return ord(s)
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if sys.version_info[1] == 1:
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def tobytes(s):
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try:
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return s.encode('latin-1')
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except:
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return ''.join(s)
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else:
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def tobytes(s):
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if isinstance(s, unicode):
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return s.encode("latin-1")
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else:
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return ''.join(s)
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else:
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def b(s):
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return s.encode("latin-1") # utf-8 would cause some side-effects we don't want
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def bchr(s):
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return bytes([s])
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def bstr(s):
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if isinstance(s,str):
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return bytes(s,"latin-1")
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else:
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return bytes(s)
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def bord(s):
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return s
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def tobytes(s):
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if isinstance(s,bytes):
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return s
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else:
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if isinstance(s,str):
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return s.encode("latin-1")
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else:
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return bytes(s)
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# vim:set ts=4 sw=4 sts=4 expandtab:
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