Combining cryptography and watermarking to secure revocable iris templates

Biometric cryptosystems have recently evolved as a means for solving key management issues as well as protecting biometric templates. In this paper, we propose the combination of cryptography with Least Significant Bit - Discrete Wavelet Transform (LSB-DWT) watermarking to secure iris templates. The key-binding bio-cryptosystem is based on fuzzy sketches that handle intra-class variability by using error correction codes. Hadamard and Reed-Solomon codes are used to correct both random and burst errors that occur in iris codes. To achieve revocability a user-specific iris shuffling algorithm is used. We used the CASIA iris database in our experiments and were able to retrieve a 210 bit key with 0 False Acceptance Rate (FAR) and 0.07% False Rejection Rate (FRR). The proposed system is also capable of withstanding minor spatial and frequency watermarking attacks without major degradation in the performance.