/contrib/bind9/doc/arm/man.isc-hmac-fixup.html
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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="id2653052"></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="id2653068"></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="id2653085"></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.ch10.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</body> 122</html>