cpython/Doc/library/md5.rst

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:mod:`md5` --- MD5 message digest algorithm
===========================================
.. module:: md5
:synopsis: RSA's MD5 message digest algorithm.
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:deprecated:
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.. deprecated:: 2.5
Use the :mod:`hashlib` module instead.
.. index::
single: message digest, MD5
single: checksum; MD5
This module implements the interface to RSA's MD5 message digest algorithm (see
also Internet :rfc:`1321`). Its use is quite straightforward: use :func:`new`
to create an md5 object. You can now feed this object with arbitrary strings
using the :meth:`update` method, and at any point you can ask it for the
:dfn:`digest` (a strong kind of 128-bit checksum, a.k.a. "fingerprint") of the
concatenation of the strings fed to it so far using the :meth:`digest` method.
For example, to obtain the digest of the string ``'Nobody inspects the spammish
repetition'``::
>>> import md5
>>> m = md5.new()
>>> m.update("Nobody inspects")
>>> m.update(" the spammish repetition")
>>> m.digest()
'\xbbd\x9c\x83\xdd\x1e\xa5\xc9\xd9\xde\xc9\xa1\x8d\xf0\xff\xe9'
More condensed::
>>> md5.new("Nobody inspects the spammish repetition").digest()
'\xbbd\x9c\x83\xdd\x1e\xa5\xc9\xd9\xde\xc9\xa1\x8d\xf0\xff\xe9'
The following values are provided as constants in the module and as attributes
of the md5 objects returned by :func:`new`:
.. data:: digest_size
The size of the resulting digest in bytes. This is always ``16``.
The md5 module provides the following functions:
.. function:: new([arg])
Return a new md5 object. If *arg* is present, the method call ``update(arg)``
is made.
.. function:: md5([arg])
For backward compatibility reasons, this is an alternative name for the
:func:`new` function.
An md5 object has the following methods:
.. method:: md5.update(arg)
Update the md5 object with the string *arg*. Repeated calls are equivalent to a
single call with the concatenation of all the arguments: ``m.update(a);
m.update(b)`` is equivalent to ``m.update(a+b)``.
.. method:: md5.digest()
Return the digest of the strings passed to the :meth:`update` method so far.
This is a 16-byte string which may contain non-ASCII characters, including null
bytes.
.. method:: md5.hexdigest()
Like :meth:`digest` except the digest is returned as a string of length 32,
containing only hexadecimal digits. This may be used to exchange the value
safely in email or other non-binary environments.
.. method:: md5.copy()
Return a copy ("clone") of the md5 object. This can be used to efficiently
compute the digests of strings that share a common initial substring.
.. seealso::
Module :mod:`sha`
Similar module implementing the Secure Hash Algorithm (SHA). The SHA algorithm
is considered a more secure hash.