1<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" 2 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" 3 [<!ENTITY mdash "—">]> 4<!-- 5 - Copyright (C) 2010, 2013, 2014 Internet Systems Consortium, Inc. ("ISC") 6 - 7 - Permission to use, copy, modify, and/or distribute this software for any 8 - purpose with or without fee is hereby granted, provided that the above 9 - copyright notice and this permission notice appear in all copies. 10 - 11 - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 12 - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 13 - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 14 - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 15 - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 16 - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 17 - PERFORMANCE OF THIS SOFTWARE. 18--> 19 20<refentry id="man.isc-hmac-fixup"> 21 <refentryinfo> 22 <date>April 28, 2013</date> 23 </refentryinfo> 24 25 <refmeta> 26 <refentrytitle><application>isc-hmac-fixup</application></refentrytitle> 27 <manvolnum>8</manvolnum> 28 <refmiscinfo>BIND9</refmiscinfo> 29 </refmeta> 30 31 <refnamediv> 32 <refname><application>isc-hmac-fixup</application></refname> 33 <refpurpose>fixes HMAC keys generated by older versions of BIND</refpurpose> 34 </refnamediv> 35 36 <docinfo> 37 <copyright> 38 <year>2010</year> 39 <year>2013</year> 40 <year>2014</year> 41 <holder>Internet Systems Consortium, Inc. ("ISC")</holder> 42 </copyright> 43 </docinfo> 44 45 <refsynopsisdiv> 46 <cmdsynopsis> 47 <command>isc-hmac-fixup</command> 48 <arg choice="req"><replaceable class="parameter">algorithm</replaceable></arg> 49 <arg choice="req"><replaceable class="parameter">secret</replaceable></arg> 50 </cmdsynopsis> 51 </refsynopsisdiv> 52 53 <refsect1> 54 <title>DESCRIPTION</title> 55 <para> 56 Versions of BIND 9 up to and including BIND 9.6 had a bug causing 57 HMAC-SHA* TSIG keys which were longer than the digest length of the 58 hash algorithm (i.e., SHA1 keys longer than 160 bits, SHA256 keys 59 longer than 256 bits, etc) to be used incorrectly, generating a 60 message authentication code that was incompatible with other DNS 61 implementations. 62 </para> 63 <para> 64 This bug has been fixed in BIND 9.7. However, the fix may 65 cause incompatibility between older and newer versions of 66 BIND, when using long keys. <command>isc-hmac-fixup</command> 67 modifies those keys to restore compatibility. 68 </para> 69 <para> 70 To modify a key, run <command>isc-hmac-fixup</command> and 71 specify the key's algorithm and secret on the command line. If the 72 secret is longer than the digest length of the algorithm (64 bytes 73 for SHA1 through SHA256, or 128 bytes for SHA384 and SHA512), then a 74 new secret will be generated consisting of a hash digest of the old 75 secret. (If the secret did not require conversion, then it will be 76 printed without modification.) 77 </para> 78 </refsect1> 79 80 <refsect1> 81 <title>SECURITY CONSIDERATIONS</title> 82 <para> 83 Secrets that have been converted by <command>isc-hmac-fixup</command> 84 are shortened, but as this is how the HMAC protocol works in 85 operation anyway, it does not affect security. RFC 2104 notes, 86 "Keys longer than [the digest length] are acceptable but the 87 extra length would not significantly increase the function 88 strength." 89 </para> 90 </refsect1> 91 92 <refsect1> 93 <title>SEE ALSO</title> 94 <para> 95 <citetitle>BIND 9 Administrator Reference Manual</citetitle>, 96 <citetitle>RFC 2104</citetitle>. 97 </para> 98 </refsect1> 99 100 <refsect1> 101 <title>AUTHOR</title> 102 <para><corpauthor>Internet Systems Consortium</corpauthor> 103 </para> 104 </refsect1> 105 106</refentry><!-- 107 - Local variables: 108 - mode: sgml 109 - End: 110--> 111