[MLS] Group ID

Marek Jankowski <mjankowski309@gmail.com> Wed, 05 June 2019 06:01 UTC

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From: Marek Jankowski <mjankowski309@gmail.com>
Date: Tue, 11 Jun 2019 16:33:15 +0200
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Subject: [MLS] Group ID
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Hi,
Regarding some issues that were raised in the last couple of months, I
wonder if we should hide the group ID from the DS. I think the group ID is
valuable metadata -- the DS may keep track of it and by that identify
sudden changes in the traffic, which may leak information.
Please consider the following alternatives:
group_id[n] = HKDF-Expand-Label(confirmation_key[n-1],group_id[n-1],
"group_id", 4)
I am aware it does not support reordering, But I'm sure one can figure an
alternative that does.

Marek.