Subject: [Emu] NIST KDF & EAP-GPSK

From: "Tschofenig, Hannes" <[email-masked]>
Date: Thu, 16 Nov 2006 09:54:15 +0100

Hi all, 

at the EMU working group meeting we received some feedback regarding the
usage of the NIST KDF in EAP-GPSK. 
In order to make progress with the document we would like to get some
more information about the suggested change to the document. 
Some NIST documents have been mentioned. Could someone point us to them?

Ciao
Hannes

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From: Charles Clancy <[email-masked]>
Date: Thu, 16 Nov 2006 09:42:32 -0500

The one mentioned during the session was SP 800-56A, if I recall 
correctly.  See:

http://csrc.nist.gov/publications/nistpubs/800-56A/sp800-56A_May-3-06.pdf

The title, "Recommendation for Pair-Wise Key Establishment Schemes Using 
Discrete Logarithm Cryptography", seems to indicate applicability might 
be limited; however, section 5.8 addresses KDFs based on shared secrets.

Two KDFs are presented in the document, along with some requirements on 
how keys are handled and how a keying hierarchy should be implemented. 
I think the KDF in section 5.8.1 seems appropriate.  It requires the use 
of a hash function, and not a MAC function, so only our HMAC-SHA256 
ciphersuite would be compliant, provided we tweaked the KDF.

For the AES ciphersuite, we could always define the KDF as a "key push" 
distribution system using AES keywrap, if we were super-worried about 
FIPS 140-2 compliance.  (I think this is a bad idea, but I'm just 
throwing it out there.)

-- 
t. charles clancy, ph.d.  <>  [email-masked]  <>  www.cs.umd.edu/~clancy

Tschofenig, Hannes wrote:
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