On Friday 31 January 2014 01:28:20 MFPA wrote: > <mid:1703510.WrKrPo3DPU@mani>, Johannes Zarl wrote: > > If the same email-address is used together with the > > same key for a long time, it effectively ties the > > email-address to a person for all practical concerns. > > After all, you are communicating via email with someone > > you have never seen. > > Didn't two or three people on this list all use the same key to sign > messages to this list a few years ago, for quite a while before > anybody noticed?
If a mail program were to implement this automatic-persona-signature scheme, that wouldn't prevent this kind of fooling around. But I still think it could improve the awareness for this sort of thing (beyond the current state as described in xkcd: https://xkcd.com/1181/) > > If the initial communication was subject to a > > MITM-attack, the key would change as soon as the MITM > > attack stops or gets sidestepped. The quality of this > > "canary" improves with the number of signatures over an > > extended time. > > If the MITM attack lasts "an extended time" all the signatures would > be on the key of the MITM-attacker... You are right - that's the implicit problem in a system without trust-anchor: you only ever can prove that a problem occurred, not that everything is fine. Basically it's a "physical" approach instead of a "mathematical" one: in mathematics you can prove everything from a few axioms (the trust-anchor). In physics you can never be certain, but we keep watching the world and whenever we spot an inconsistency with our model we investigate. > > In either scenario, you would notice that something was > > afoul as soon as the key changes and investigate. > > You _might_ notice. If a mail program implements this (and automatic signing would need explicit support from the mail program), then it would also implement a notification. Implementing the auto-signing part without using the information for spotting problems is like implementing PGP without support for key expiration and revocation ;-) Cheers, Johannes _______________________________________________ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
