84 lines
3.7 KiB
HTML
84 lines
3.7 KiB
HTML
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- Copyright (C) 2010 Internet Systems Consortium, Inc. ("ISC")
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<!-- $Id$ -->
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>isc-hmac-fixup</title>
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<meta name="generator" content="DocBook XSL Stylesheets V1.71.1">
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</head>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
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<a name="man.isc-hmac-fixup"></a><div class="titlepage"></div>
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<div class="refnamediv">
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<h2>Name</h2>
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<p><span class="application">isc-hmac-fixup</span> — fixes HMAC keys generated by older versions of BIND</p>
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</div>
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<div class="refsynopsisdiv">
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<h2>Synopsis</h2>
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<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>
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</div>
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<div class="refsect1" lang="en">
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<a name="id2543352"></a><h2>DESCRIPTION</h2>
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<p>
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Versions of BIND 9 up to and including BIND 9.6 had a bug causing
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HMAC-SHA* TSIG keys which were longer than the digest length of the
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hash algorithm (i.e., SHA1 keys longer than 160 bits, SHA256 keys
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longer than 256 bits, etc) to be used incorrectly, generating a
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message authentication code that was incompatible with other DNS
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implementations.
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</p>
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<p>
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This bug has been fixed in BIND 9.7. However, the fix may
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cause incompatibility between older and newer versions of
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BIND, when using long keys. <span><strong class="command">isc-hmac-fixup</strong></span>
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modifies those keys to restore compatibility.
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</p>
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<p>
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To modify a key, run <span><strong class="command">isc-hmac-fixup</strong></span> and
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specify the key's algorithm and secret on the command line. If the
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secret is longer than the digest length of the algorithm (64 bytes
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for SHA1 through SHA256, or 128 bytes for SHA384 and SHA512), then a
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new secret will be generated consisting of a hash digest of the old
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secret. (If the secret did not require conversion, then it will be
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printed without modification.)
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</p>
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</div>
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<div class="refsect1" lang="en">
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<a name="id2543376"></a><h2>SECURITY CONSIDERATIONS</h2>
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<p>
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Secrets that have been converted by <span><strong class="command">isc-hmac-fixup</strong></span>
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are shortened, but as this is how the HMAC protocol works in
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operation anyway, it does not affect security. RFC 2104 notes,
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"Keys longer than [the digest length] are acceptable but the
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extra length would not significantly increase the function
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strength."
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</p>
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</div>
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<div class="refsect1" lang="en">
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<a name="id2543389"></a><h2>SEE ALSO</h2>
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<p>
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<em class="citetitle">BIND 9 Administrator Reference Manual</em>,
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<em class="citetitle">RFC 2104</em>.
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</p>
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</div>
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<div class="refsect1" lang="en">
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<a name="id2543406"></a><h2>AUTHOR</h2>
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<p><span class="corpauthor">Internet Systems Consortium</span>
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</p>
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</div>
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</div></body>
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</html>
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