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1N/A<
p><
span class="application">isc-hmac-fixup</
span> — fixes HMAC keys generated by older versions of BIND</
p>
1N/A<
div class="refsynopsisdiv">
1N/A<
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>
1N/A<
div class="refsect1" lang="en">
1N/A<
a name="id2625997"></
a><
h2>DESCRIPTION</
h2>
1N/A Versions of BIND 9 up to and including BIND 9.6 had a bug causing
1N/A HMAC-SHA* TSIG keys which were longer than the digest length of the
1N/A hash algorithm (
i.e., SHA1 keys longer than 160 bits, SHA256 keys
1N/A longer than 256 bits, etc) to be used incorrectly, generating a
1N/A message authentication code that was incompatible with other DNS
1N/A This bug has been fixed in BIND 9.7. However, the fix may
1N/A cause incompatibility between older and newer versions of
1N/A BIND, when using long keys. <
span><
strong class="command">isc-hmac-fixup</
strong></
span>
1N/A modifies those keys to restore compatibility.
1N/A To modify a key, run <
span><
strong class="command">isc-hmac-fixup</
strong></
span> and
1N/A specify the key's algorithm and secret on the command line. If the
1N/A secret is longer than the digest length of the algorithm (64 bytes
1N/A for SHA1 through SHA256, or 128 bytes for SHA384 and SHA512), then a
1N/A new secret will be generated consisting of a hash digest of the old
1N/A secret. (If the secret did not require conversion, then it will be
1N/A printed without modification.)
1N/A<
div class="refsect1" lang="en">
1N/A<
a name="id2670057"></
a><
h2>SECURITY CONSIDERATIONS</
h2>
1N/A Secrets that have been converted by <
span><
strong class="command">isc-hmac-fixup</
strong></
span>
1N/A are shortened, but as this is how the HMAC protocol works in
1N/A operation anyway, it does not affect security. RFC 2104 notes,
1N/A "Keys longer than [the digest length] are acceptable but the
1N/A extra length would not significantly increase the function
1N/A<
div class="refsect1" lang="en">
1N/A<
a name="id2670073"></
a><
h2>SEE ALSO</
h2>
1N/A <
em class="citetitle">BIND 9 Administrator Reference Manual</
em>,
1N/A <
em class="citetitle">RFC 2104</
em>.
1N/A<
div class="refsect1" lang="en">
1N/A<
a name="id2670090"></
a><
h2>AUTHOR</
h2>
1N/A<
p><
span class="corpauthor">Internet Systems Consortium</
span>
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