basic functionalty
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modules/Crypto/Hash/__init__.py
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176
modules/Crypto/Hash/__init__.py
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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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"""Hashing algorithms
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Hash functions take arbitrary binary strings as input, and produce a random-like output
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of fixed size that is dependent on the input; it should be practically infeasible
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to derive the original input data given only the hash function's
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output. In other words, the hash function is *one-way*.
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It should also not be practically feasible to find a second piece of data
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(a *second pre-image*) whose hash is the same as the original message
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(*weak collision resistance*).
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Finally, it should not be feasible to find two arbitrary messages with the
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same hash (*strong collision resistance*).
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The output of the hash function is called the *digest* of the input message.
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In general, the security of a hash function is related to the length of the
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digest. If the digest is *n* bits long, its security level is roughly comparable
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to the the one offered by an *n/2* bit encryption algorithm.
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Hash functions can be used simply as a integrity check, or, in
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association with a public-key algorithm, can be used to implement
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digital signatures.
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The hashing modules here all support the interface described in `PEP
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247`_ , "API for Cryptographic Hash Functions".
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.. _`PEP 247` : http://www.python.org/dev/peps/pep-0247/
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:undocumented: _MD2, _MD4, _RIPEMD160, _SHA224, _SHA256, _SHA384, _SHA512
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"""
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__all__ = ['HMAC', 'MD2', 'MD4', 'MD5', 'RIPEMD160', 'SHA1',
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'SHA224', 'SHA256', 'SHA384', 'SHA512', 'CMAC']
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__revision__ = "$Id$"
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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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def new(algo, *args):
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"""Initialize a new hash object.
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The first argument to this function may be an algorithm name or another
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hash object.
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This function has significant overhead. It's recommended that you instead
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import and use the individual hash modules directly.
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"""
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# Try just invoking algo.new()
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# We do this first so that this is the fastest.
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try:
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new_func = algo.new
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except AttributeError:
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pass
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else:
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return new_func(*args)
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# Try getting the algorithm name.
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if isinstance(algo, str):
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name = algo
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else:
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try:
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name = algo.name
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except AttributeError:
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raise ValueError("unsupported hash type %r" % (algo,))
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# Got the name. Let's see if we have a PyCrypto implementation.
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try:
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new_func = _new_funcs[name]
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except KeyError:
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# No PyCrypto implementation. Try hashlib.
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try:
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import hashlib
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except ImportError:
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# There is no hashlib.
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raise ValueError("unsupported hash type %s" % (name,))
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return hashlib.new(name, *args)
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else:
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# We have a PyCrypto implementation. Instantiate it.
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return new_func(*args)
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# This dict originally gets the following _*_new methods, but its members get
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# replaced with the real new() methods of the various hash modules as they are
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# used. We do it without locks to improve performance, which is safe in
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# CPython because dict access is atomic in CPython. This might break PyPI.
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_new_funcs = {}
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def _md2_new(*args):
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from Crypto.Hash import MD2
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_new_funcs['MD2'] = _new_funcs['md2'] = MD2.new
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return MD2.new(*args)
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_new_funcs['MD2'] = _new_funcs['md2'] = _md2_new
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del _md2_new
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def _md4_new(*args):
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from Crypto.Hash import MD4
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_new_funcs['MD4'] = _new_funcs['md4'] = MD4.new
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return MD4.new(*args)
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_new_funcs['MD4'] = _new_funcs['md4'] = _md4_new
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del _md4_new
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def _md5_new(*args):
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from Crypto.Hash import MD5
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_new_funcs['MD5'] = _new_funcs['md5'] = MD5.new
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return MD5.new(*args)
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_new_funcs['MD5'] = _new_funcs['md5'] = _md5_new
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del _md5_new
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def _ripemd160_new(*args):
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from Crypto.Hash import RIPEMD160
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_new_funcs['RIPEMD160'] = _new_funcs['ripemd160'] = \
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_new_funcs['RIPEMD'] = _new_funcs['ripemd'] = RIPEMD160.new
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return RIPEMD160.new(*args)
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_new_funcs['RIPEMD160'] = _new_funcs['ripemd160'] = \
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_new_funcs['RIPEMD'] = _new_funcs['ripemd'] = _ripemd160_new
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del _ripemd160_new
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def _sha1_new(*args):
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from Crypto.Hash import SHA1
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_new_funcs['SHA1'] = _new_funcs['sha1'] = \
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_new_funcs['SHA'] = _new_funcs['sha'] = SHA1.new
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return SHA1.new(*args)
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_new_funcs['SHA1'] = _new_funcs['sha1'] = \
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_new_funcs['SHA'] = _new_funcs['sha'] = _sha1_new
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del _sha1_new
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def _sha224_new(*args):
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from Crypto.Hash import SHA224
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_new_funcs['SHA224'] = _new_funcs['sha224'] = SHA224.new
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return SHA224.new(*args)
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_new_funcs['SHA224'] = _new_funcs['sha224'] = _sha224_new
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del _sha224_new
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def _sha256_new(*args):
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from Crypto.Hash import SHA256
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_new_funcs['SHA256'] = _new_funcs['sha256'] = SHA256.new
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return SHA256.new(*args)
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_new_funcs['SHA256'] = _new_funcs['sha256'] = _sha256_new
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del _sha256_new
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def _sha384_new(*args):
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from Crypto.Hash import SHA384
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_new_funcs['SHA384'] = _new_funcs['sha384'] = SHA384.new
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return SHA384.new(*args)
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_new_funcs['SHA384'] = _new_funcs['sha384'] = _sha384_new
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del _sha384_new
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def _sha512_new(*args):
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from Crypto.Hash import SHA512
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_new_funcs['SHA512'] = _new_funcs['sha512'] = SHA512.new
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return SHA512.new(*args)
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_new_funcs['SHA512'] = _new_funcs['sha512'] = _sha512_new
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del _sha512_new
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