Key distribution is generally the weakest link in any public use crypto system, both because it's a fundamentally hard problem and because people are the weakes

Key distribution is generally the weakest link in any public use crypto system, both because it's a fundamentally hard problem and because people are the weakest link. If you built a "peer to peer" crypto system based around offline token sharing for identity, 99% of your users would email or text message their secrets to each other and more importantly 99+% of your users would accept a token they received from the other party that way.