Re: [Tcpcrypt] Initial questions

Stephen Farrell <stephen.farrell@cs.tcd.ie> Wed, 25 June 2014 11:07 UTC

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Date: Wed, 25 Jun 2014 12:04:35 +0100
From: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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To: Sandy Harris <sandyinchina@gmail.com>, tcpcrypt@ietf.org
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Subject: Re: [Tcpcrypt] Initial questions
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Sorry, I omitted the link to the saag discussion about
algorithm agility (thanks Marcelo for spotting that).

The initial thread starts at [1], and iang's disagreement
at [2].

S.

[1] https://www.ietf.org/mail-archive/web/saag/current/msg04844.html
[2] https://www.ietf.org/mail-archive/web/saag/current/msg04960.html

On 25/06/14 01:17, Stephen Farrell wrote:
> 
> Hiya,
> 
> On 24/06/14 21:22, Sandy Harris wrote:
>>>> I can say that failure to accommodate alg agility will almost certainly
>>>> cause the IESG to reject this as a standard, based on precedents
>>>> for some time.
>>
>> OK, we need some agility, both because it is a good safety measure
>> and because IESG will likely insist.
> 
> Planning for what to do on the basis of what the IESG might
> conclude at this level of detail is not a great plan. For
> example, by the time the spec reaches the IESG the relevant
> folks may have changed (I'm one of 'em for now btw) and/or
> opinions as to the desirable mechanisms for algorithm
> agility could have changed somewhat.
> 
>>
>> BUT the fewer choices there are, the simpler the protocol can be.
>> That has costs in "design, implementation, testing & auditing" &
>> extra options may mean a risk of downgrade attacks.
> 
> There is a separate (sporadic) discussion on the saag list about
> this. [1] Russ has written a draft trying to capture algorithm
> agility in the form of a BCP. iang isn't keen but may so far be
> in the rough. OTOH, we do have issues - its just dumb that there
> are 300+ TLS ciphersuites, even with the combinatoric explosion,
> and then there's vanity/national crypto as well that might also
> be thought of differently here, or not, we'll see.
> 
> So basically, I'd say leave this one until the WG which I hope
> will be formed very shortly gets to discussing its protocol
> details. And at that point I hope we see an argument about what's
> the right thing to do.
> 
> S.
> 
> 
> 
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