An update to the United Airlines app now makes it possible for passengers to scan their own passports with their phone cameras. Although there are plenty of kiosks in-airport that let travelers to this already, this is a first in terms of mobile apps.
The passport-scanning feature works in a similar way to how you're able to make secure mobile deposits by snapping a picture of a cheque. Travelers have 24 hours before departure to scan their passports with the United app, so that Jumio, a third party management service can verify a person's credentials. Once verified, a traveler is able to claim their boarding pass and proceed to catch their flight. With the app, it's also possible for users to see the last boarding time for a flight, so that they can board at their leisure.