Proving identity is a routine part of modern daily life. Many people must show a driver's license to buy alcohol at a store, flash an ID card to security guards at work, enter passwords and passcodes to retrieve email and other private information, and answer security validation questions when calling banks or credit card companies for customer service.
Authentication is also getting easier for people: Take the iPhone, for example. Unlocking the early versions required a multi-digit passcode. Then Apple introduced Touch ID, which would unlock the phone with a fingerprint reader. The latest version, just out, is the iPhone X, which can use its camera to perform facial recognition to authenticate a user.
As a software security researcher looking at authentication technologies for hand-held devices, I am fully aware that the technologies change, but the challenge remains the same: How can a digital system authenticate an analog human's identity?