Abstract
This paper presents a challenge/response-based biometric image scrambling scheme which attempts to overcome the liveness and retransmission issues of biometric image transmission over insecure communication channel. An intelligent biometric sensor is proposed which has computational power to receive challenges from authentication server and generates response against the challenge with encrypted biometric image. The fractional Fourier transform (FRT) has been used for a biometric image encryption process with its scaling factors and random phase masks as the secret keys. The random phase masks of FRT are chaotically generated by piecewise linear chaotic map (PWLCM) to further improve the encryption security. Experimental and simulation results have demonstrated that the proposed system is secure, robust, and deters the risks of attacks for secure biometric image transmission.