1<!-- 2 - Copyright (C) 2004-2015 Internet Systems Consortium, Inc. ("ISC") 3 - Copyright (C) 2000-2003 Internet Software Consortium. 4 - 5 - Permission to use, copy, modify, and/or distribute this software for any 6 - purpose with or without fee is hereby granted, provided that the above 7 - copyright notice and this permission notice appear in all copies. 8 - 9 - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 10 - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 11 - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 12 - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 13 - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 14 - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 15 - PERFORMANCE OF THIS SOFTWARE. 16--> 17<!-- $Id: man.isc-hmac-fixup.html,v 1.5 2015/09/03 07:33:34 christos Exp $ --> 18<html> 19<head> 20<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 21<title>isc-hmac-fixup</title> 22<meta name="generator" content="DocBook XSL Stylesheets V1.71.1"> 23<link rel="start" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual"> 24<link rel="up" href="Bv9ARM.ch13.html" title="Manual pages"> 25<link rel="prev" href="man.genrandom.html" title="genrandom"> 26<link rel="next" href="man.nsec3hash.html" title="nsec3hash"> 27</head> 28<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 29<div class="navheader"> 30<table width="100%" summary="Navigation header"> 31<tr><th colspan="3" align="center"><span class="application">isc-hmac-fixup</span></th></tr> 32<tr> 33<td width="20%" align="left"> 34<a accesskey="p" href="man.genrandom.html">Prev</a>�</td> 35<th width="60%" align="center">Manual pages</th> 36<td width="20%" align="right">�<a accesskey="n" href="man.nsec3hash.html">Next</a> 37</td> 38</tr> 39</table> 40<hr> 41</div> 42<div class="refentry" lang="en"> 43<a name="man.isc-hmac-fixup"></a><div class="titlepage"></div> 44<div class="refnamediv"> 45<h2>Name</h2> 46<p><span class="application">isc-hmac-fixup</span> — fixes HMAC keys generated by older versions of BIND</p> 47</div> 48<div class="refsynopsisdiv"> 49<h2>Synopsis</h2> 50<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> 51</div> 52<div class="refsect1" lang="en"> 53<a name="id2665763"></a><h2>DESCRIPTION</h2> 54<p> 55 Versions of BIND 9 up to and including BIND 9.6 had a bug causing 56 HMAC-SHA* TSIG keys which were longer than the digest length of the 57 hash algorithm (i.e., SHA1 keys longer than 160 bits, SHA256 keys 58 longer than 256 bits, etc) to be used incorrectly, generating a 59 message authentication code that was incompatible with other DNS 60 implementations. 61 </p> 62<p> 63 This bug has been fixed in BIND 9.7. However, the fix may 64 cause incompatibility between older and newer versions of 65 BIND, when using long keys. <span><strong class="command">isc-hmac-fixup</strong></span> 66 modifies those keys to restore compatibility. 67 </p> 68<p> 69 To modify a key, run <span><strong class="command">isc-hmac-fixup</strong></span> and 70 specify the key's algorithm and secret on the command line. If the 71 secret is longer than the digest length of the algorithm (64 bytes 72 for SHA1 through SHA256, or 128 bytes for SHA384 and SHA512), then a 73 new secret will be generated consisting of a hash digest of the old 74 secret. (If the secret did not require conversion, then it will be 75 printed without modification.) 76 </p> 77</div> 78<div class="refsect1" lang="en"> 79<a name="id2665790"></a><h2>SECURITY CONSIDERATIONS</h2> 80<p> 81 Secrets that have been converted by <span><strong class="command">isc-hmac-fixup</strong></span> 82 are shortened, but as this is how the HMAC protocol works in 83 operation anyway, it does not affect security. RFC 2104 notes, 84 "Keys longer than [the digest length] are acceptable but the 85 extra length would not significantly increase the function 86 strength." 87 </p> 88</div> 89<div class="refsect1" lang="en"> 90<a name="id2665806"></a><h2>SEE ALSO</h2> 91<p> 92 <em class="citetitle">BIND 9 Administrator Reference Manual</em>, 93 <em class="citetitle">RFC 2104</em>. 94 </p> 95</div> 96<div class="refsect1" lang="en"> 97<a name="id2665892"></a><h2>AUTHOR</h2> 98<p><span class="corpauthor">Internet Systems Consortium</span> 99 </p> 100</div> 101</div> 102<div class="navfooter"> 103<hr> 104<table width="100%" summary="Navigation footer"> 105<tr> 106<td width="40%" align="left"> 107<a accesskey="p" href="man.genrandom.html">Prev</a>�</td> 108<td width="20%" align="center"><a accesskey="u" href="Bv9ARM.ch13.html">Up</a></td> 109<td width="40%" align="right">�<a accesskey="n" href="man.nsec3hash.html">Next</a> 110</td> 111</tr> 112<tr> 113<td width="40%" align="left" valign="top"> 114<span class="application">genrandom</span>�</td> 115<td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td> 116<td width="40%" align="right" valign="top">�<span class="application">nsec3hash</span> 117</td> 118</tr> 119</table> 120</div> 121<p style="text-align: center;">BIND 9.10.2-P4</p> 122</body> 123</html> 124