lib/Crypto/Hash/MD5.py

# -*- coding: utf-8 -*-
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"""MD5 cryptographic hash algorithm.

MD5 is specified in RFC1321_ and produces the 128 bit digest of a message.

    >>> from Crypto.Hash import MD5
    >>>
    >>> h = MD5.new()
    >>> h.update(b'Hello')
    >>> print h.hexdigest()

MD5 stand for Message Digest version 5, and it was invented by Rivest in 1991.

This algorithm is insecure. Do not use it for new designs.

.. _RFC1321: http://tools.ietf.org/html/rfc1321 
"""

from __future__ import nested_scopes

_revision__ = "$Id$"

__all__ = ['new', 'block_size', 'digest_size']

from Crypto.Util.py3compat import *
if sys.version_info[0] == 2 and sys.version_info[1] == 1:
    from Crypto.Util.py21compat import *

def __make_constructor():
    try:
        # The md5 module is deprecated in Python 2.6, so use hashlib when possible.
        from hashlib import md5 as _hash_new
    except ImportError:
        from md5 import new as _hash_new

    h = _hash_new()
    if hasattr(h, 'new') and hasattr(h, 'name') and hasattr(h, 'digest_size') and hasattr(h, 'block_size'):
        # The module from stdlib has the API that we need.  Just use it.
        return _hash_new
    else:
        # Wrap the hash object in something that gives us the expected API.
        _copy_sentinel = object()
        class _MD5(object):
            digest_size = 16
            block_size = 64
            name = "md5"
            def __init__(self, *args):
                if args and args[0] is _copy_sentinel:
                    self._h = args[1]
                else:
                    self._h = _hash_new(*args)
            def copy(self):
                return _MD5(_copy_sentinel, self._h.copy())
            def update(self, *args):
                f = self.update = self._h.update
                f(*args)
            def digest(self):
                f = self.digest = self._h.digest
                return f()
            def hexdigest(self):
                f = self.hexdigest = self._h.hexdigest
                return f()
        _MD5.new = _MD5
        return _MD5

new = __make_constructor()
del __make_constructor

#: The size of the resulting hash in bytes.
digest_size = new().digest_size

#: The internal block size of the hash algorithm in bytes.
block_size = new().block_size