Biometrics images provide the identity of the user based on the physiological or behavioral characteristics of the person. Nowadays, for various purposes, Biometric Images are transmitted over the network. By recent digital technologies, it is possible to attack biometric image. So, to authenticate the biometric images and repaired the tampered images becomes a serious concern. To solve this problem, two enhanced blind authentication techniques are proposed. The first authentication method based on the secret sharing scheme with a data repair capability via the use of the PNG image. In this method, the digital biometric image is combining with the alpha channel to form a PNG image. An authentication signal is transformed into several secret shares by using secret sharing scheme and then embedded into an alpha channel plane of biometric image, which is used for repairing purpose. The second authentication method based on watermarking and bin mapping scheme. In this method, authentication signals are generated by dividing the grayscale range into bins, which provides the double functions of tampering detection and data repairing. Hence, by using these techniques it is possible to authenticate biometric images and also possible to repair if there is any attack in biometric images.

Keywords: Biometric Image, Authentication, Repairing, Secret sharing, Bin mapping