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Filename : MD5.py
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# -*- 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 
"""

_revision__ = "$Id$"

__all__ = ['new', 'digest_size', 'MD5Hash' ]

from Crypto.Util.py3compat import *
from Crypto.Hash.hashalgo import HashAlgo

try:
    # The md5 module is deprecated in Python 2.6, so use hashlib when possible.
    import hashlib
    hashFactory = hashlib.md5

except ImportError:
    import md5
    hashFactory = md5

class MD5Hash(HashAlgo):
    """Class that implements an MD5 hash
    
    :undocumented: block_size
    """

    #: ASN.1 Object identifier (OID)::
    #:
    #:  id-md5      OBJECT IDENTIFIER ::= {
    #:      iso(1) member-body(2) us(840) rsadsi(113549)
    #:       digestAlgorithm(2) 5
    #:  }
    #:
    #: This value uniquely identifies the MD5 algorithm.
    oid = b('\x06\x08\x2a\x86\x48\x86\xf7\x0d\x02\x05')

    digest_size = 16
    block_size = 64

    def __init__(self, data=None):
        HashAlgo.__init__(self, hashFactory, data)

    def new(self, data=None):
        return MD5Hash(data)

def new(data=None):
    """Return a fresh instance of the hash object.

    :Parameters:
       data : byte string
        The very first chunk of the message to hash.
        It is equivalent to an early call to `MD5Hash.update()`.
        Optional.

    :Return: A `MD5Hash` object
    """
    return MD5Hash().new(data)

#: The size of the resulting hash in bytes.
digest_size = MD5Hash.digest_size

#: The internal block size of the hash algorithm in bytes.
block_size = MD5Hash.block_size