Physical features include: fingerprint, vein, palm shape, retina, iris, body odor, face shape, even blood vessels, DNA, bones and so on. Behavioral characteristics include: signature, pronunciation, walking gait and so on. Biometric identification system samples biological features, extracts their unique features and converts them into digital codes, and then forms feature templates with these codes. When people interact with the identity authentication system, the identity authentication system will compare their features with the feature templates in the database to determine whether they match, and then decide to accept or reject the person.