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Re: [STDS-802-11-TGBE] Discussion on CID 5360 (DCN 575r2)

Hi Yongho,

Given that there's no specification text for how this works in the draft, there's no agreement for how this works. 

This would also mean that everytime a STA would retry a MMPDU on another link, it would need to re-encrypt the frame. That is terribly inefficient and problematic since MPDUs are processed entirely differently from MMPDUs. Also, there would need to be adjustments to PN processing.

Cheers,

Mike



On Thu, May 5, 2022 at 5:15 PM Yongho Seok <yongho.seok@xxxxxxxxx> wrote:
Hi Mike, 
No, I think that it has been discussed in TGbe a long time ago. 
At least, I can provide one related document that was submitted by Guogang. Group didn't accept this document. 
https://mentor.ieee.org/802.11/dcn/21/11-21-0571-03-00be-pdt-mld-security-for-individual-management-frame.docx

Thanks, 
Yongho 

2022년 5월 5일 (목) 오후 2:08, M Montemurro <montemurro.michael@xxxxxxxxx>님이 작성:
Hi Yongho, 

I disagree and do not support that. It hasn’t been discussed nor is the text in the specification. 

Cheers,

Mike

On Thu, May 5, 2022 at 4:51 PM Yongho Seok <yongho.seok@xxxxxxxxx> wrote:
Hello Mark, 
Please see my response below. 
Thanks, 
Yongho 



2022년 5월 5일 (목) 오후 1:37, <mark.hamilton2152@xxxxxxxxx>님이 작성:

Yongho/all,

 

Apologies for dropping into this discussion late/in the middle, and perhaps this has been discussed and/or updated since last I knew.  But I thought:

  • Individually addressed Data frames are ‘generated’ by the AP MLD’s upper MAC (also where it came into the AP from the DS), and thus encrypted as described, agreed.
[YH: In the MAC header, A1 and A2 are set to the STA MAC address.
When constructing the AAD, A1 and A2 are changed to the MLD MAC addresses associated with the A1 and A2 of the MAC header.]  
  • Group addressed Data frames are passed from the AP MLD upper MAC to the affiliated AP’s upper MAC(s) for transmission, and are encrypted using link-specific group keys.  I believe we’re still agreed.
  • But, individually addressed Management frames could be generated within the AP MLD’s upper MAC, and directed to a specific non-AP MLD peer.  Such MMPDUs (and hence their “MPDU”) would have A1 and A2 set to the MLD addresses of the RXr and TXr MLDs, respectively. 
[YH: In the MAC header, A1 and A2 are set to the STA MAC address. (Always Address fields in the MAC header use the STA MAC address.)
When constructing the AAD, A1 and A2 have no change. The A1 and A2 of the MAC header are used.]  
  • So, while I agree with the quote below, the implication is that such Management frames would have A1/A2 set to the MPDU Address 1/2 field, yes, but this would not result in different addresses if/when retransmitted on another link.

 

Did I “miss a memo”?

 

Thanks.  Mark

 

From: Yongho Seok <yongho.seok@xxxxxxxxx>
Sent: Thursday, May 5, 2022 2:18 PM
To: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBE] Discussion on CID 5360 (DCN 575r2)

 

Hi Gaurav, 

Thanks for initiating this discussion. Because I suggested this NOTE, I may provide the background. 

Current AAD construction rule is that only individually addressed Data frames use the MLD MAC address instead of the STA MAC address. 

If dot11MultiLinkActivated is true, for both the transmitter and intended receiver of the MPDU, either of To DS or From DS subfields in the MAC header of the MPDU is set to 1, and the MPDU is an individually addressed Data frame, then A1 is set to:
—the MLD MAC address of the intended receiver MLD of the MPDU.
—otherwise, Al is set to MPDU Address 1 field.

So, when another frame like a management frame is retransmitted on a different link, the frame is re-encrypted. The below note clarifies this. If people have a concern on the below NOTE, they have to comment on the above spec text. 

 

Thanks, 

Yongho 

 

2022년 5월 5일 (목) 오후 12:49, Gaurav Patwardhan <gauravpatwardhan1@xxxxxxxxx>님이 작성:

Hi,

 

Initiating this thread to discuss CID 5360 from DCN 575r2 which I presented today.  The discussion on the call was for the following NOTE:

 

NOTE – (#5360) For MLO, when an individually addressed management frame is retransmitted on another link, the encrypted data is modified on retransmission.

 

 

Regards,

Gaurav Patwardhan

(Hewlett Packard Enterprise)

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