Atalla Key Block (AKB)

From: Ernest Hammingweight (
Date: 07/13/04

Date: 13 Jul 2004 00:56:55 -0700


Are the details of the AKB for exchanging 3-DES keys publicly
available. Atalla marketing brochures make some claims about its
security but all I can see is that there's:
(1) An 8 byte header
(2) A comma
(3) A 24 byte encrypted block (CBC mode)
(4) A comma
(5) A MAC

In particular I don't understand the format of the header and am
unsure about the KEK used for the block; is the KEK a variant of some
other key?. And is the IV=0 or, maybe, derived from the header?

Is this supposed to be a proprietary (yuk) format; i.e. do I need to
buy an NSM to get the details? I seem to remember reading that the
ANSI X.9 committee is supposed to be evaluating AKB for adoption as a
standard? Anybody know if there's any truth in that?