DHS's Transportation Security Administration is currently testing an encrypted 2-D bar code that includes all the information from a boarding pass and is digitally signed to ensure the data hasn’t been altered.
In the pilot, passengers show the bar code to TSA identity checkers, who use a scanner to read the image off the passenger’s smartphone, and then check the person’s identification against the decrypted information.
The system also works using public-key cryptography, which lets the TSA use scanners that don’t need to connect to airline databases, and they don’t store records of who is traveling.
Really, really cool. Smart use of crypto to solve a real security problem. I never thought I'd say these three words but: Good job TSA!