> The way to fix it is equally obvious: Verify the accuracy of the boarding passes at the security checkpoints. If passengers had to scan their boarding passes as they went through screening, the computer could verify that the boarding pass already matched to the photo ID also matched the data in the computer. Close the authentication triangle and the vulnerability disappears.
The last time I flew, they scanned my boarding pass at the security checkpoint and made a bunch of random marks all over it. I would be surprised if they accepted your second, unadulterated boarding pass at the gate.
https://www.schneier.com/blog/archives/2006/11/forge_your_ow...
https://www.schneier.com/blog/archives/2012/10/hacking_tsa_p...
Someone even created a boarding pass generator to demonstrate their weakness. They promptly got their door busted in by the feds.