Alaska Airlines is removing kiosks that print passengers' boarding passes and telling people to download or print them. The airline has already removed kiosks at nine airports so far.

Encryption in a boarding-pass bar code would make forgeries easy to spot, White said. Technology for encrypted bar codes is being used commercially, TSA acting technology chief Robin Kane said.

Portland International Airport officials said the change is unrelated to the renovations underway at the airport, and that the decision to do away with boarding pass printing was made by Alaska.