Security Experts Warn Hand Signs in Selfies Could Expose Biometric Data

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Security experts warn that common hand gestures in selfies and group photos could expose people to biometric data theft, as advances in AI make fingerprint extraction from images increasingly feasible.

The warning gained attention after Chinese security expert Li Chang demonstrated on a reality show how AI tools could reconstruct a celebrity’s fingerprints from a photo. According to Chang, fingerprints may be captured clearly if the fingertips face the camera directly from within roughly 1.5 meters, while partial details may still be recoverable from images taken at greater distances.

The issue has resonated strongly in South Korea, where hand gestures such as V signs, finger hearts, and “flower poses” are widely used in everyday photos and celebrity appearances. Concerns are growing that highly detailed smartphone images shared online could unintentionally expose sensitive biometric information.

The risks are not purely theoretical. Chinese media previously reported a case in Hangzhou in which criminals allegedly attempted to unlock a smart door lock using fingerprint data reconstructed from a photo the homeowner posted online.

Experts say that several conditions must align for fingerprint reconstruction to succeed, such as sufficient lighting, image sharpness, shooting distance, and camera quality. Still, researchers warn that advances in AI image enhancement and biometric analysis are lowering the technical barriers to potential abuse.

Pei Zhiyong, director of the Qianxin Industry Security Research Center, is advising users to limit the number of close-up hand photos shared online and to avoid storing fingerprint credentials on devices or systems they do not fully trust.