Bengaluru, Aug. 6 -- On a foggy January morning in 2017, 17 passengers voluntarily stepped into an experimental lane at Bengaluru's Kempegowda International Airport to test a new way of boarding flights: no identity (ID) card, no ticket, no boarding pass. A simple scanner cross-verified the passengers' fingerprints with India's unique identity system, Aadhaar, and matched them against the flight manifest.

The pilot project, done in partnership with Jet Airways, which was still operational back then, went smoothly. But it was much harder to pull off, than it seemed.

"Back then, everything was manual," recalls Suresh Khadakbhavi, now chief executive officer (CEO) of the Digi Yatra Foundation. "We realized that identity and travel document...