[zxcvbn4038]

I can’t think of an infallible means of issuing a ticket completely offline, that usually gets into security by obscurity and eventually someone will be motivated to break that.

I think the signed ticket scheme would have been better used for redeeming already issued tickets or tickets to identity verified previously.

Issuing a ticket with pre-signed identity token is essentially a good faith transaction - it is not guaranteed to be valid end to end - but you can compare against a blacklist of identities at redemption time to limit the impact of someone abusing the system.

The commuter rail lines in New York want to charge a premium for issuing a ticket onboard so they have this whole scheme where you have to activate an e-ticket before you leave the station and then it’s only good for an hour, and 90% of the time they don’t validate it - just see that a QR code is on your phone - the other ten percent of the time they want you to swipe or do something to prove it’s not just a screen shot. It can lead to a lot of drama in areas where the cell service is weak or none, or accidentally closed the app, and people don’t have cash on them. I think signing the tickets could solve a lot of the drama. If the conductor has internet connectivity he can validate and redeem tickets in real time, if not then the conductor can validate in real time, make sure no one else on the train has a duplicate ticket, and redeem in bulk when they get into cell range again.