Re: [dane] I-D Action: draft-ietf-dane-smime-04.txt

Viktor Dukhovni <viktor1dane@dukhovni.org> Thu, 09 January 2014 17:39 UTC

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Date: Thu, 9 Jan 2014 17:39:43 +0000
From: Viktor Dukhovni <viktor1dane@dukhovni.org>
To: dane@ietf.org
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References: <89AE05E1-BC6C-46BA-A4CC-A8F29070096D@vpnc.org> <CEF43EFD.F8FB%bdickson@verisign.com>
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Subject: Re: [dane] I-D Action: draft-ietf-dane-smime-04.txt
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On Thu, Jan 09, 2014 at 05:08:28PM +0000, Dickson, Brian wrote:

> So instead of "encoding" per se, what about using a hash function?

An intriguing suggestion.  If the hash is HMAC-SHA1(domain, username),
its hex representation is 40 octets which fits comfortably into a
DNS label.  Dictionary harvesting attacks by following NSEC records
are a bit harder, since HMAC with the domain as a key makes the
use of rainbow tables less useful.

-- 
	Viktor.