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<title>15.2 md5 -- MD5 message digest algorithm
</title>
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<H1><A NAME=
"SECTION0017200000000000000000">
15.2 <tt class=
"module">md5
</tt> --
MD5 message digest algorithm
</A>
<A NAME=
"module-md5"></A>
This module implements the interface to RSA's MD5 message digest
<a id='l2h-
4820' xml:id='l2h-
4820'
></a>
algorithm (see also Internet
<a class=
"rfc" id='rfcref-
92073' xml:id='rfcref-
92073'
href=
"http://www.faqs.org/rfcs/rfc1321.html">RFC
1321</a>). Its use is quite
straightforward: use
<tt class=
"function">new()
</tt> to create an md5 object.
You can now feed this object with arbitrary strings using the
<tt class=
"method">update()
</tt> method, and at any point you can ask it for the
<i class=
"dfn">digest
</i> (a strong kind of
128-bit checksum,
a.k.a. ``fingerprint'') of the concatenation of the strings fed to it
so far using the
<tt class=
"method">digest()
</tt> method.
<a id='l2h-
4821' xml:id='l2h-
4821'
></a>
For example, to obtain the digest of the string
<code>'Nobody inspects
the spammish repetition'
</code>:
<div class=
"verbatim"><pre>
>>> m = md5.new()
>>> m.update(
"Nobody inspects")
>>> m.update(
" the spammish repetition")
'\xbbd\x9c\x83\xdd\x1e\xa5\xc9\xd9\xde\xc9\xa1\x8d\xf0\xff\xe9'
<div class=
"verbatim"><pre>
>>> 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
<tt class=
"function">new()
</tt>:
<dl><dt><b><tt id='l2h-
4813' xml:id='l2h-
4813'
>digest_size
</tt></b></dt>
The size of the resulting digest in bytes. This is always
md5 objects support the following methods:
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4814' xml:id='l2h-
4814'
class=
"function">new
</tt></b>(
</nobr></td>
<td><var></var><big>[
</big><var>arg
</var><big>]
</big><var></var>)
</td></tr></table></dt>
Return a new md5 object. If
<var>arg
</var> is present, the method call
<code>update(
<var>arg
</var>)
</code> is made.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4815' xml:id='l2h-
4815'
class=
"function">md5
</tt></b>(
</nobr></td>
<td><var></var><big>[
</big><var>arg
</var><big>]
</big><var></var>)
</td></tr></table></dt>
For backward compatibility reasons, this is an alternative name for the
<tt class=
"function">new()
</tt> function.
An md5 object has the following methods:
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4816' xml:id='l2h-
4816'
class=
"method">update
</tt></b>(
</nobr></td>
<td><var>arg
</var>)
</td></tr></table></dt>
Update the md5 object with the string
<var>arg
</var>. Repeated calls are
equivalent to a single call with the concatenation of all the
arguments:
<code>m.update(a); m.update(b)
</code> is equivalent to
<code>m.update(a+b)
</code>.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4817' xml:id='l2h-
4817'
class=
"method">digest
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Return the digest of the strings passed to the
<tt class=
"method">update()
</tt>
method so far. This is a
16-byte string which may contain
non-ASCII characters, including null bytes.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4818' xml:id='l2h-
4818'
class=
"method">hexdigest
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Like
<tt class=
"method">digest()
</tt> 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
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4819' xml:id='l2h-
4819'
class=
"method">copy
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Return a copy (``clone'') of the md5 object. This can be used to
efficiently compute the digests of strings that share a common initial
<p class=
"heading">See Also:
</p>
<dl compact=
"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-sha.html">sha
</a></tt>:
</b>
<dd>Similar module implementing the Secure Hash
Algorithm (SHA). The SHA algorithm is considered a
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<span class=
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2.4.2, documentation updated on
28 September
2005.
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