Subject: [Roll] AES-CCM not AES-CCM*

From: Robert Cragie <[email-masked]>
Date: Thu, 02 Sep 2010 16:56:25 +0100

I think we should be specifying AES-CCM not AES-CCM* in the RPL 
specification. There is some IPR surrounding AES-CCM* (US 2005/0154882), 
plus only AES-CCM itself is referenced in FIPS 140-2.

The only real difference between AES-CCM* and AES-CCM is the encrypt 
only mode, which is illegal in AES-CCM. However, encrypt only is not 
used in RPL. Authentication only can be achieved in AES-CCM by setting 
the A data to the header concatenated with the payload and the payload 
to be encrypted to the null string and Plen to 0 (see 
http://csrc.nist.gov/publications/nistpubs/800-38C/SP800-38C_updated-July20_2007.pdf). 
In practice, this makes no difference to the RPL specification.

Robert
-- 

Robert Cragie (Pacific Gas & Electric)

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