I ve been thinking on how people could use ecash tokens physically and securely in a doomsday scenario where internet and electricity is off and tap to pay seems to be the solution. How?
1. You have a doomsday app that lets people send in their ecash inexchange of an encrypted representation that token using public key cryptography.
2. The encrypted token is then loaded on to a card for use.
3. Marchants and other people have devices that can verify the authenticity of the token while the exchange them.
4. When internet is back, they can then redeem their ecash using the same doomsday app that gave them the encrypted tokens.
I don't really know if this is a good idea. But my problem was " how can we exchange ecash tokens physically for prolonged period of no internet while trusting the validity of the token without access to the mint?"