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/Doc/library/md5.rst

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 1
 2:mod:`md5` --- MD5 message digest algorithm
 3===========================================
 4
 5.. module:: md5
 6   :synopsis: RSA's MD5 message digest algorithm.
 7   :deprecated:
 8
 9
10.. deprecated:: 2.5
11   Use the :mod:`hashlib` module instead.
12
13.. index::
14   single: message digest, MD5
15   single: checksum; MD5
16
17This module implements the interface to RSA's MD5 message digest  algorithm (see
18also Internet :rfc:`1321`).  Its use is quite straightforward: use :func:`new`
19to create an md5 object. You can now feed this object with arbitrary strings
20using the :meth:`update` method, and at any point you can ask it for the
21:dfn:`digest` (a strong kind of 128-bit checksum, a.k.a. "fingerprint") of the
22concatenation of the strings fed to it so far using the :meth:`digest` method.
23
24For example, to obtain the digest of the string ``'Nobody inspects the spammish
25repetition'``:
26
27   >>> import md5
28   >>> m = md5.new()
29   >>> m.update("Nobody inspects")
30   >>> m.update(" the spammish repetition")
31   >>> m.digest()
32   '\xbbd\x9c\x83\xdd\x1e\xa5\xc9\xd9\xde\xc9\xa1\x8d\xf0\xff\xe9'
33
34More condensed:
35
36   >>> md5.new("Nobody inspects the spammish repetition").digest()
37   '\xbbd\x9c\x83\xdd\x1e\xa5\xc9\xd9\xde\xc9\xa1\x8d\xf0\xff\xe9'
38
39The following values are provided as constants in the module and as attributes
40of the md5 objects returned by :func:`new`:
41
42
43.. data:: digest_size
44
45   The size of the resulting digest in bytes.  This is always ``16``.
46
47The md5 module provides the following functions:
48
49
50.. function:: new([arg])
51
52   Return a new md5 object.  If *arg* is present, the method call ``update(arg)``
53   is made.
54
55
56.. function:: md5([arg])
57
58   For backward compatibility reasons, this is an alternative name for the
59   :func:`new` function.
60
61An md5 object has the following methods:
62
63
64.. method:: md5.update(arg)
65
66   Update the md5 object with the string *arg*.  Repeated calls are equivalent to a
67   single call with the concatenation of all the arguments: ``m.update(a);
68   m.update(b)`` is equivalent to ``m.update(a+b)``.
69
70
71.. method:: md5.digest()
72
73   Return the digest of the strings passed to the :meth:`update` method so far.
74   This is a 16-byte string which may contain non-ASCII characters, including null
75   bytes.
76
77
78.. method:: md5.hexdigest()
79
80   Like :meth:`digest` except the digest is returned as a string of length 32,
81   containing only hexadecimal digits.  This may  be used to exchange the value
82   safely in email or other non-binary environments.
83
84
85.. method:: md5.copy()
86
87   Return a copy ("clone") of the md5 object.  This can be used to efficiently
88   compute the digests of strings that share a common initial substring.
89
90
91.. seealso::
92
93   Module :mod:`sha`
94      Similar module implementing the Secure Hash Algorithm (SHA).  The SHA algorithm
95      is considered a more secure hash.
96