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--- This message came from the IEEE 802.11 Working Group Reflector ---Since the A-MSDU header is part of the payload, the encrypted portion of the payload is different between the original and the "retransmission" (it really should be called something else, to distinguish it from a normal MAC-layer retransmission).
A different PN has to be used for the GCR "retransmission". --- Henry Ptasinski henry@xxxxxxxxxx On 04/26/2013 09:53 AM, Alex Ashley wrote:
--- This message came from the IEEE 802.11 Working Group Reflector --- When a frame is retransmitted by GCR, the original MSDU is encapsulated inside an A-MSDU and then transmitted to the GCR concealment address. The encapsulation is used so that the original destination group address is preserved. The frame is sent to the GCR concealment address so that legacy STAs don't receive the retransmission. Alex ----------------------------------------Date: Fri, 26 Apr 2013 15:13:43 +0000 From: dharkins@xxxxxxxxxxxxxxxxx Subject: Re: [STDS-802-11] CID 1109 from 11mc LB193 To: STDS-802-11@xxxxxxxxxxxxxxxxx --- This message came from the IEEE 802.11 Working Group Reflector --- That would only be true if the data being protected by CCMP differed. If CCMP protected data is just encapsulated in some different container then there would be no leakage. (Full disclosure: I don't really understand how GCR works) Dan. On 4/26/13 7:09 AM, "Henry Ptasinski" <henry@xxxxxxxxxx> wrote:--- This message came from the IEEE 802.11 Working Group Reflector --- If the payloads between the original transmission and the "retransmission" are different because of e.g. encapsulation changes, using the same PN breaks the 802.11 security design. At a minimum, it would leak information about the payload. --- Henry Ptasinski henry@xxxxxxxxxx On 04/20/2013 10:32 AM, Hamilton, Mark wrote:--- This message came from the IEEE 802.11 Working Group Reflector --- Henry, That sort of logic was our conclusion in Orlando discussions as well. However, note the unsolicited retry (non GCR-SP mode) uses the same sequence number as was used for the original transmission (despite the MSDU having been reframed into a different MPDU). So, we definitely have "special rules" at play. The question to the GCR experts is whether this was intended to extend to the PN. My personal opinion is that it can/should not cover the PN. The sequence number 'intentional replay' provides enough information to GCR-aware receivers to correctly understand the frames being sent, and to not confuse non-GCR-aware STAs. There is no reason to apply special rules to the PN, which would require 'pushing higher up the stack' special-case GCR-awareness. Mark -----Original Message----- From: *** IEEE stds-802-11 List *** [mailto:STDS-802-11@xxxxxxxx] On Behalf Of Henry Ptasinski Sent: Friday, April 19, 2013 5:58 PM To: STDS-802-11@xxxxxxxxxxxxxxxxx Subject: Re: [STDS-802-11] CID 1109 from 11mc LB193 --- This message came from the IEEE 802.11 Working Group Reflector --- If I understand clause 10.24.16.3.5 correctly, the payload of the retransmission may be different than the payload of the original frame (specifically, by the addition of A-MSDU framing in some cases). If that's true, the "retransmission" would need to use a different PN to avoid encrypting two different payloads with the same PN. --- Henry Ptasinski henry@xxxxxxxxxx On 04/19/2013 01:47 PM, Dan Harkins wrote:--- This message came from the IEEE 802.11 Working Group Reflector --- Hello, CID 1109 from LB193 concerns CCMP protection of multicast frames that get concealed with GCR, specifically is a different PN used when retransmitting using GCR? The 11mc group discussed this in Orlando and decided the discussion should go to the list. And here it is, on the list. The assumption in Orlando was that a different PN will be used for the retransmitted MSDU because it will be concealed inside a different MPDU. But that assumption was made by people (like me) who are not familiar with GCR and therefore the assumption might very well be wrong. Can anyone who is familiar with GCR please comment? If anyone has implemented GCR, please say what you did so this CID is resolved properly. thank you, Dan. ________________________________________________________________________ _______ If you wish to be removed from this reflector, do not send your request to this reflector - it will have no effect. Instead, go to http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11 and then press the LEAVE button. If there is no LEAVE button here, try http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-RO. Further information can be found at: http://www.ieee802.org/11/Email_Subscribe.html ________________________________________________________________________ ________________________________________________________________________________ ______ If you wish to be removed from this reflector, do not send your request to this reflector - it will have no effect. Instead, go to http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11 and then press the LEAVE button. If there is no LEAVE button here, try http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-RO. Further information can be found at: http://www.ieee802.org/11/Email_Subscribe.html _________________________________________________________________________ ______ _________________________________________________________________________ ______ If you wish to be removed from this reflector, do not send your request to this reflector - it will have no effect. Instead, go to http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11 and then press the LEAVE button. If there is no LEAVE button here, try http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-RO. Further information can be found at: http://www.ieee802.org/11/Email_Subscribe.html _________________________________________________________________________ ________________________________________________________________________________ _____ If you wish to be removed from this reflector, do not send your request to this reflector - it will have no effect. Instead, go to http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11 and then press the LEAVE button. If there is no LEAVE button here, try http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-RO. Further information can be found at: http://www.ieee802.org/11/Email_Subscribe.html __________________________________________________________________________ ____________________________________________________________________________________ If you wish to be removed from this reflector, do not send your request to this reflector - it will have no effect. Instead, go to http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11 and then press the LEAVE button. If there is no LEAVE button here, try http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-RO. Further information can be found at: http://www.ieee802.org/11/Email_Subscribe.html ______________________________________________________________________________________________________________________________________________________________ If you wish to be removed from this reflector, do not send your request to this reflector - it will have no effect. Instead, go to http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11 and then press the LEAVE button. If there is no LEAVE button here, try http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-RO. Further information can be found at: http://www.ieee802.org/11/Email_Subscribe.html _______________________________________________________________________________
_______________________________________________________________________________ If you wish to be removed from this reflector, do not send your request to this reflector - it will have no effect. Instead, go to http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11 and then press the LEAVE button. If there is no LEAVE button here, try http://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-RO. Further information can be found at: http://www.ieee802.org/11/Email_Subscribe.html _______________________________________________________________________________