[messaging] Autocrypt 1.0

[Vincent Breitmoser]

> The recipient of this message will accept and use the incorrect
> gossiped keys for group replies, thus sending unreadable messages.

I don't think that's right? Keys received directly take precedence over
gossip keys, so everyone who participates in the group and has sent at
least a single message, will no longer have his key overridden within
that group.

> Advertising "prefer-encrypt: nopreference" doesn't give the advertiser
> control over whether to receive encrypted messages, it just makes it
> discretionary for senders, for the next 35 days.  If lots of senders
> always encrypt when "available", then you won't get much of a test
> period.

Those senders are the target audience for prefer-encrypt=mutual. A major
reason of being very shy about encryption by default is that as long as
encryption remains an at least somewhat conscious decision for most
communication peers, problems that might occur with particular
recipients stay much more solvable at the social level.

 - V