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"""Hashing algorithms

Hash functions take arbitrary binary strings as input, and produce a random-like output
of fixed size that is dependent on the input; it should be practically infeasible 
to derive the original input data given only the hash function's
output. In other words, the hash function is *one-way*.

It should also not be practically feasible to find a second piece of data
(a *second pre-image*) whose hash is the same as the original message
(*weak collision resistance*).

Finally, it should not be feasible to find two arbitrary messages with the
same hash (*strong collision resistance*).

The output of the hash function is called the *digest* of the input message.
In general, the security of a hash function is related to the length of the
digest. If the digest is *n* bits long, its security level is roughly comparable
to the the one offered by an *n/2* bit encryption algorithm.

Hash functions can be used simply as a integrity check, or, in
association with a public-key algorithm, can be used to implement
digital signatures.

The hashing modules here all support the interface described in `PEP
247`_ , "API for Cryptographic Hash Functions". 

.. _`PEP 247` : http://www.python.org/dev/peps/pep-0247/

:undocumented: _MD2, _MD4, _RIPEMD160, _SHA224, _SHA256, _SHA384, _SHA512
"""

__all__ = ['HMAC', 'MD2', 'MD4', 'MD5', 'RIPEMD', 'SHA',
           'SHA224', 'SHA256', 'SHA384', 'SHA512']
__revision__ = "$Id$"