Heh, that's definitely the messier part of this. It all depends on your threat model and the scale of the community you're running. For a small group of trusted

Heh, that's definitely the messier part of this. It all depends on your threat model and the scale of the community you're running. For a small group of trusted friends, one could distribute keys in person and enforce time-based key expiry. For larger groups of strangers... I'm not sure. Reelin's web of trust idea seems like a good start. The only ideas coming to my mind right now require burning down the community and starting over whenever compromised. This is definitely an interesting and difficult challenge! What ideas do you have in mind?