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From the page: > In environments where cross-signing and verification are enabled, adding a new unverified user adds a warning to the room to indicate that unv
by bscphil 4y ago
From the page:
> In environments where cross-signing and verification are enabled, adding a new unverified user adds a warning to the room to indicate that unverified devices are present. However, it is possible for a homeserver to add a verified user to rooms without changing the security properties of the room. This allows a colluding homeserver and verified user to eavesdrop on rooms not intended for them. In other words, the warning regarding unverified devices is independent to whether the device is intended to participate in the specific room. Users may, of course, simply ignore warnings.
If I'm not mistaken this is not just a "warning" - Matrix clients will actively refuse to encrypt messages to the new recipient until they are verified in this situation.
The last time I seriously looked at Matrix (2019-2020ish), cross-signing and verification were essentially required for real security in chats. It sounds to me like (a) the worst case scenario vis-à-vis the "rogue server" is that things regress back to where they were in 2019, and (b) there's an issue where if everyone in a room has a rogue user validated, a rogue server can add the rogue user to a room that the user is not supposed to be invited to, without triggering a warning. This latter issue strikes me as something that should definitely be fixed (if it hasn't already been), but far from fatal for smaller chats.
"They killed it. It's dead." strikes me as an enormous reach.