Le mercredi 1 juillet 2026, 00:58:52 heure d’été d’Europe centrale Travis Burtrum a écrit :
Hi all,
As stated in xsf@ this is trivially MITM'able isn't it ? I can advertise your XID at my JID and then when anyone sends me a challenge I just send it to you and reply back with your response to me?
Signing just the nonce is clearly inadequate, I think signing the nonce + sender jid + responder jid (separated with something that can't be in any of the above, I think a null byte should do?) would work, and you wouldn't need to keep timestamp but if you do that should be concatenated+signed too.
Thanks, moparisthebest
Hi moparisthebest, yes the current challenge is flawed, it was already pointed out in previous discussion. I was waiting for the XEP to be published to make the change (to not change anything during council evaluation). There have been a lot of valuable feedback, I'll try to publish a corrected version soon. Best, Goffi