man.isc-hmac-fixup.html revision 0eea9763d88e3edf9b6de585f7cfbb08de977124
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync<!--
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - Copyright (C) 2004-2015 Internet Systems Consortium, Inc. ("ISC")
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - Copyright (C) 2000-2003 Internet Software Consortium.
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync -
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - Permission to use, copy, modify, and/or distribute this software for any
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - purpose with or without fee is hereby granted, provided that the above
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - copyright notice and this permission notice appear in all copies.
e64031e20c39650a7bc902a3e1aba613b9415deevboxsync -
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync - PERFORMANCE OF THIS SOFTWARE.
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync-->
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync<!-- $Id$ -->
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync<html>
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync<head>
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync<title>isc-hmac-fixup</title>
6c91ce3517ab5d910faaf35a29fab35df44a201bvboxsync<meta name="generator" content="DocBook XSL Stylesheets V1.71.1">
<link rel="start" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual">
<link rel="up" href="Bv9ARM.ch13.html" title="Manual pages">
<link rel="prev" href="man.genrandom.html" title="genrandom">
<link rel="next" href="man.nsec3hash.html" title="nsec3hash">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<div class="navheader">
<table width="100%" summary="Navigation header">
<tr><th colspan="3" align="center"><span class="application">isc-hmac-fixup</span></th></tr>
<tr>
<td width="20%" align="left">
<a accesskey="p" href="man.genrandom.html">Prev</a>�</td>
<th width="60%" align="center">Manual pages</th>
<td width="20%" align="right">�<a accesskey="n" href="man.nsec3hash.html">Next</a>
</td>
</tr>
</table>
<hr>
</div>
<div class="refentry" lang="en">
<a name="man.isc-hmac-fixup"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2>Name</h2>
<p><span class="application">isc-hmac-fixup</span> &#8212; fixes HMAC keys generated by older versions of BIND</p>
</div>
<div class="refsynopsisdiv">
<h2>Synopsis</h2>
<div class="cmdsynopsis"><p><code class="command">isc-hmac-fixup</code> {<em class="replaceable"><code>algorithm</code></em>} {<em class="replaceable"><code>secret</code></em>}</p></div>
</div>
<div class="refsect1" lang="en">
<a name="id2623346"></a><h2>DESCRIPTION</h2>
<p>
Versions of BIND 9 up to and including BIND 9.6 had a bug causing
HMAC-SHA* TSIG keys which were longer than the digest length of the
hash algorithm (i.e., SHA1 keys longer than 160 bits, SHA256 keys
longer than 256 bits, etc) to be used incorrectly, generating a
message authentication code that was incompatible with other DNS
implementations.
</p>
<p>
This bug has been fixed in BIND 9.7. However, the fix may
cause incompatibility between older and newer versions of
BIND, when using long keys. <span><strong class="command">isc-hmac-fixup</strong></span>
modifies those keys to restore compatibility.
</p>
<p>
To modify a key, run <span><strong class="command">isc-hmac-fixup</strong></span> and
specify the key's algorithm and secret on the command line. If the
secret is longer than the digest length of the algorithm (64 bytes
for SHA1 through SHA256, or 128 bytes for SHA384 and SHA512), then a
new secret will be generated consisting of a hash digest of the old
secret. (If the secret did not require conversion, then it will be
printed without modification.)
</p>
</div>
<div class="refsect1" lang="en">
<a name="id2669795"></a><h2>SECURITY CONSIDERATIONS</h2>
<p>
Secrets that have been converted by <span><strong class="command">isc-hmac-fixup</strong></span>
are shortened, but as this is how the HMAC protocol works in
operation anyway, it does not affect security. RFC 2104 notes,
"Keys longer than [the digest length] are acceptable but the
extra length would not significantly increase the function
strength."
</p>
</div>
<div class="refsect1" lang="en">
<a name="id2669811"></a><h2>SEE ALSO</h2>
<p>
<em class="citetitle">BIND 9 Administrator Reference Manual</em>,
<em class="citetitle">RFC 2104</em>.
</p>
</div>
<div class="refsect1" lang="en">
<a name="id2669828"></a><h2>AUTHOR</h2>
<p><span class="corpauthor">Internet Systems Consortium</span>
</p>
</div>
</div>
<div class="navfooter">
<hr>
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left">
<a accesskey="p" href="man.genrandom.html">Prev</a>�</td>
<td width="20%" align="center"><a accesskey="u" href="Bv9ARM.ch13.html">Up</a></td>
<td width="40%" align="right">�<a accesskey="n" href="man.nsec3hash.html">Next</a>
</td>
</tr>
<tr>
<td width="40%" align="left" valign="top">
<span class="application">genrandom</span>�</td>
<td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td>
<td width="40%" align="right" valign="top">�<span class="application">nsec3hash</span>
</td>
</tr>
</table>
</div>
<p style="text-align: center;">BIND 9.11.0pre-alpha</p>
</body>
</html>