<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>14.2. hmac — Keyed-Hashing for Message Authentication — Python v2.6.6 documentation</title>
<link rel="stylesheet" href="../_static/default.css" type="text/css" />
<link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: '../',
VERSION: '2.6.6',
COLLAPSE_MODINDEX: false,
FILE_SUFFIX: '.html',
HAS_SOURCE: true
};
</script>
<script type="text/javascript" src="../_static/jquery.js"></script>
<script type="text/javascript" src="../_static/doctools.js"></script>
<link rel="search" type="application/opensearchdescription+xml"
title="Search within Python v2.6.6 documentation"
href="../_static/opensearch.xml"/>
<link rel="author" title="About these documents" href="../about.html" />
<link rel="copyright" title="Copyright" href="../copyright.html" />
<link rel="top" title="Python v2.6.6 documentation" href="../index.html" />
<link rel="up" title="14. Cryptographic Services" href="crypto.html" />
<link rel="next" title="14.3. md5 — MD5 message digest algorithm" href="md5.html" />
<link rel="prev" title="14.1. hashlib — Secure hashes and message digests" href="hashlib.html" />
<link rel="shortcut icon" type="image/png" href="../_static/py.png" />
</head>
<body>
<div class="related">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
accesskey="I">index</a></li>
<li class="right" >
<a href="../modindex.html" title="Global Module Index"
accesskey="M">modules</a> |</li>
<li class="right" >
<a href="md5.html" title="14.3. md5 — MD5 message digest algorithm"
accesskey="N">next</a> |</li>
<li class="right" >
<a href="hashlib.html" title="14.1. hashlib — Secure hashes and message digests"
accesskey="P">previous</a> |</li>
<li><img src="../_static/py.png" alt=""
style="vertical-align: middle; margin-top: -1px"/></li>
<li><a href="../index.html">Python v2.6.6 documentation</a> »</li>
<li><a href="index.html" >The Python Standard Library</a> »</li>
<li><a href="crypto.html" accesskey="U">14. Cryptographic Services</a> »</li>
</ul>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body">
<div class="section" id="module-hmac">
<h1>14.2. <tt class="xref docutils literal"><span class="pre">hmac</span></tt> — Keyed-Hashing for Message Authentication<a class="headerlink" href="#module-hmac" title="Permalink to this headline">¶</a></h1>
<p class="versionadded">
<span class="versionmodified">New in version 2.2.</span></p>
<p>This module implements the HMAC algorithm as described by <span class="target" id="index-374"></span><a class="reference external" href="http://tools.ietf.org/html/rfc2104.html"><strong>RFC 2104</strong></a>.</p>
<dl class="function">
<dt id="hmac.new">
<tt class="descclassname">hmac.</tt><tt class="descname">new</tt><big>(</big><em>key</em><span class="optional">[</span>, <em>msg</em><span class="optional">[</span>, <em>digestmod</em><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#hmac.new" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a new hmac object. If <em>msg</em> is present, the method call <tt class="docutils literal"><span class="pre">update(msg)</span></tt>
is made. <em>digestmod</em> is the digest constructor or module for the HMAC object to
use. It defaults to the <tt class="xref docutils literal"><span class="pre">hashlib.md5()</span></tt> constructor.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">The md5 hash has known weaknesses but remains the default for backwards
compatibility. Choose a better one for your application.</p>
</div>
</dd></dl>
<p>An HMAC object has the following methods:</p>
<dl class="method">
<dt id="hmac.hmac.update">
<tt class="descclassname">hmac.</tt><tt class="descname">update</tt><big>(</big><em>msg</em><big>)</big><a class="headerlink" href="#hmac.hmac.update" title="Permalink to this definition">¶</a></dt>
<dd>Update the hmac object with the string <em>msg</em>. Repeated calls are equivalent to
a single call with the concatenation of all the arguments: <tt class="docutils literal"><span class="pre">m.update(a);</span>
<span class="pre">m.update(b)</span></tt> is equivalent to <tt class="docutils literal"><span class="pre">m.update(a</span> <span class="pre">+</span> <span class="pre">b)</span></tt>.</dd></dl>
<dl class="method">
<dt id="hmac.hmac.digest">
<tt class="descclassname">hmac.</tt><tt class="descname">digest</tt><big>(</big><big>)</big><a class="headerlink" href="#hmac.hmac.digest" title="Permalink to this definition">¶</a></dt>
<dd>Return the digest of the strings passed to the <a title="hmac.hmac.update" class="reference internal" href="#hmac.hmac.update"><tt class="xref docutils literal"><span class="pre">update()</span></tt></a> method so far.
This string will be the same length as the <em>digest_size</em> of the digest given to
the constructor. It may contain non-ASCII characters, including NUL bytes.</dd></dl>
<dl class="method">
<dt id="hmac.hmac.hexdigest">
<tt class="descclassname">hmac.</tt><tt class="descname">hexdigest</tt><big>(</big><big>)</big><a class="headerlink" href="#hmac.hmac.hexdigest" title="Permalink to this definition">¶</a></dt>
<dd>Like <a title="hmac.hmac.digest" class="reference internal" href="#hmac.hmac.digest"><tt class="xref docutils literal"><span class="pre">digest()</span></tt></a> except the digest is returned as a string twice the length
containing only hexadecimal digits. This may be used to exchange the value
safely in email or other non-binary environments.</dd></dl>
<dl class="method">
<dt id="hmac.hmac.copy">
<tt class="descclassname">hmac.</tt><tt class="descname">copy</tt><big>(</big><big>)</big><a class="headerlink" href="#hmac.hmac.copy" title="Permalink to this definition">¶</a></dt>
<dd>Return a copy (“clone”) of the hmac object. This can be used to efficiently
compute the digests of strings that share a common initial substring.</dd></dl>
<div class="admonition-see-also admonition seealso">
<p class="first admonition-title">See also</p>
<dl class="last docutils">
<dt>Module <a title="Secure hash and message digest algorithms." class="reference external" href="hashlib.html#module-hashlib"><tt class="xref docutils literal"><span class="pre">hashlib</span></tt></a></dt>
<dd>The Python module providing secure hash functions.</dd>
</dl>
</div>
</div>
</div>
</div>
</div>
<div class="sphinxsidebar">
<div class="sphinxsidebarwrapper">
<h4>Previous topic</h4>
<p class="topless"><a href="hashlib.html"
title="previous chapter">14.1. <tt class="docutils literal docutils literal docutils literal"><span class="pre">hashlib</span></tt> — Secure hashes and message digests</a></p>
<h4>Next topic</h4>
<p class="topless"><a href="md5.html"
title="next chapter">14.3. <tt class="docutils literal"><span class="pre">md5</span></tt> — MD5 message digest algorithm</a></p>
<h3>This Page</h3>
<ul class="this-page-menu">
<li><a href="../bugs.html">Report a Bug</a></li>
<li><a href="../_sources/library/hmac.txt"
rel="nofollow">Show Source</a></li>
</ul>
<div id="searchbox" style="display: none">
<h3>Quick search</h3>
<form class="search" action="../search.html" method="get">
<input type="text" name="q" size="18" />
<input type="submit" value="Go" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
<p class="searchtip" style="font-size: 90%">
Enter search terms or a module, class or function name.
</p>
</div>
<script type="text/javascript">$('#searchbox').show(0);</script>
</div>
</div>
<div class="clearer"></div>
</div>
<div class="related">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
>index</a></li>
<li class="right" >
<a href="../modindex.html" title="Global Module Index"
>modules</a> |</li>
<li class="right" >
<a href="md5.html" title="14.3. md5 — MD5 message digest algorithm"
>next</a> |</li>
<li class="right" >
<a href="hashlib.html" title="14.1. hashlib — Secure hashes and message digests"
>previous</a> |</li>
<li><img src="../_static/py.png" alt=""
style="vertical-align: middle; margin-top: -1px"/></li>
<li><a href="../index.html">Python v2.6.6 documentation</a> »</li>
<li><a href="index.html" >The Python Standard Library</a> »</li>
<li><a href="crypto.html" >14. Cryptographic Services</a> »</li>
</ul>
</div>
<div class="footer">
© <a href="../copyright.html">Copyright</a> 1990-2011, Python Software Foundation.
<br />
The Python Software Foundation is a non-profit corporation.
<a href="http://www.python.org/psf/donations/">Please donate.</a>
<br />
Last updated on Jul 20, 2011.
<a href="../bugs.html">Found a bug</a>?
<br />
Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 0.6.6.
</div>
</body>
</html>
Copyright 2K16 - 2K18 Indonesian Hacker Rulez