Hi,
- make
sure no more than one CTR-encrypted PDU is in a given frame (or else the
scheme is insecure)
- the
counter (the AES (block) counter not the ROC), gets incremented whenever a
new AES plaintext block is processed (an AES plaintext block has 16 bytes
which is far less than a potential text size in a PDU)
- As
the last quoted sentence says when the frame number rolls from 0xffffff to
0x000000 the ROC should be incremented
Ilan Zohar
Intel
From: owner-stds-802-16-mobile@ieee.org [mailto:owner-stds-802-16-mobile@ieee.org] On Behalf Of venkateshwarlu.v
Sent: Wednesday, June 15, 2005
11:01 AM
To:
STDS-802-16-MOBILE@listserv.ieee.org
Subject: [STDS-802-16-MOBILE]
Please clarify section 7.8.4.1.1 from P80216e/D8
I have been looking at the P802.16e/d8 specifications and
got a doubt on Encryption notes given in the document, related to 8-bit
rollover counter functionality.
Copied from standard page Number- 234
NOTE—When we start to deal with a new PDU we
have a new frame number and therefore reinitialize the counter.
When the frame number reaches 0x000000 (from
0xFFFFFF), we increment ROC.
1- Whenever there is a new PDU, how it's possible to
have a new frame number?
2- If we re-initialize the counter for every PDU, when this
counter will be incremented?
3- When to increment the ROC.
I would really appeciate, if some one could clarify this.
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