Re: [STDS-802-16] replay protection using CMAC PN
7.5.4.41
..
" The CMAC_PN_* is part of the CMAC security context and must be unique
for each MAC management message with the CMAC tuple or digest. Any tuple
value of {CMAC_PN_*, AK CMAC_KEY_*} shall not be used more than once.
The reauthentication process should be initiated (by BS or SS) to
establish a new AK before the CMAC_PN_* reaches the end of its number
space."
The spec states that it must be unique, that it starts at zero with a
new key and increments for each management message.
The spec does not contain specific receive processing rules that state
to retain the highest valid received PN and so be able to reject packets
with non monotonic PNs, but that is what is required.
This could be considered an omission.
----
David Johnston. dj.johnston@intel.com Cell: 503 380 5578, Desk: 503 712
4457
-----Original Message-----
From: T. Sundara Moorthy [mailto:sundaramoorthy@TATAELXSI.CO.IN]
Sent: Wednesday, September 12, 2007 4:19 AM
To: STDS-802-16@LISTSERV.IEEE.ORG
Subject: [STDS-802-16] replay protection using CMAC PN
Hi there,
802.16e specifies that CMAC_PN_* should be used to prevent replay attack
on
management connection, But it is not clearly mentioned how it should be
done.
Section 7.5.1.2.4: Receive Processing Rules, describes a mechanism for
replay
protection of data connection using PN of AES CCM Mode.
Is the same expected to be followed for Management connections(using
CMAC_PN_*) too?
Thanks,
T. Sundara Moorthy.