Answer: With a photo of the fingerprint.
This hack should make smartphone owners nervous. At the GeekPwn 2019 hacking conference in Shanghai, a team of Chinese hackers from Tencent Security’s X-Lab demonstrated a new method of smartphone hacking.
After taking a photograph of an audience member’s fingerprint left on a piece of glass, the team created a physical model of the person’s fingerprint using a specially developed app. For security reasons, the exact method of turning photograph into physical replica was kept secret. The resulting replicas were able to successfully unlock three smartphones and two other machines with fingerprint scanners.
Perhaps the most unnerving part is the fact that the tools required for this process were inexpensive, about U.S. $140 total. Also, the entire hack only took about 20 minutes.