Re: [kitten] WGLC on draft-ietf-kitten-aes-cts-hmac-sha2-06

Nico Williams <nico@cryptonector.com> Fri, 17 April 2015 19:06 UTC

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Date: Fri, 17 Apr 2015 14:06:14 -0500
From: Nico Williams <nico@cryptonector.com>
To: Benjamin Kaduk <kaduk@MIT.EDU>
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Subject: Re: [kitten] WGLC on draft-ietf-kitten-aes-cts-hmac-sha2-06
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On Fri, Apr 17, 2015 at 02:35:42PM -0400, Benjamin Kaduk wrote:
> On Thu, 9 Apr 2015, Jeffrey Altman wrote:
> > raised are significant.   Do we have independent review from trusted
> > cryptographers?  I'm not one so will not try to review the math.
> 
> I don't believe there was explicit "independent cryptographer" review at
> the time you wrote this.  ("Does Nico count as a cryptographer?")

"Decidedly not."

However, we have authorities we can quote as to:

 - the safety of the confounded CTS construction (which isn't new here)

 - the safety of the HMAC truncation (which isn't new here)

 - the safety of encrypt-then-MAC (which is new here for Kerberos)

 - the safety of HMAC with SHA-2 functions (we need only that they be a
   good PRF) (which is new here, of course, for Kerberos anyways)

What controversies are there?

Nico
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