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Re: [dane] Feature creep for draft-ietf-dane-smime

"Osterweil, Eric" <eosterweil@verisign.com> Thu, 13 February 2014 18:19 UTC

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From: "Osterweil, Eric" <eosterweil@verisign.com>
To: Viktor Dukhovni <viktor1dane@dukhovni.org>
Thread-Topic: [dane] Feature creep for draft-ietf-dane-smime
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Date: Thu, 13 Feb 2014 18:19:15 +0000
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References: <41938fd202ba460285b59132c29ac826@BY2PR09MB029.namprd09.prod.outlook.com> <20140206195322.GD278@mournblade.imrryr.org> <11698F58-B554-4CC8-872F-D2A3BF08986C@kirei.se> <20140206215742.GF278@mournblade.imrryr.org> <07a801cf23a1$a5b62c00$f1228400$@augustcellars.com> <E52467C0-3B6A-45D6-AFAB-6A103E587350@vpnc.org> <20140207020201.GJ278@mournblade.imrryr.org> <alpine.LFD.2.10.1402071258500.21252@bofh.nohats.ca> <20140207184155.GQ278@mournblade.imrryr.org> <66FEEA7D-D815-4536-A141-189F2CB705B9@vpnc.org> <20140207194933.GS278@mournblade.imrryr.org>
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Cc: "<dane@ietf.org>" <dane@ietf.org>
Subject: Re: [dane] Feature creep for draft-ietf-dane-smime
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On Feb 7, 2014, at 2:49 PM, Viktor Dukhovni <viktor1dane@dukhovni.org> wrote:

> On Fri, Feb 07, 2014 at 11:08:20AM -0800, Paul Hoffman wrote:
> 
>> Those existed 15 years ago, and still do. The proposal to make
>> it slightly harder for a harvester (and that's all we're suggesting)
>> adds complexity and no measurable value.
> 
> Yes, adding iterations would definitely add complexity.
> 
> Arguably HMAC(domain, localpart) is more complex than
> SHA(localpart@domain), I don't care which is used.
> 
> Either way of computing the hash of the full address, rather than
> just the local part adds no complexity, and makes off-line attacks
> more difficult (per site dictionaries, rather than global dictionaries).
> This is a free win.  There's simply no reason not to.

I have to say that I agree with Paul here.  I think the epsilon increase in security is nice, but not at the cost of the additional operational complexity.  However, the hashing-only approach has the nice side effect of fixing the label length.  That _does_ seem to solve a problem w/o some of the additional complexity.  My vote would be hashing-only approach over Base32 and HMAC.

Eric

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