On the Unlinkability of Fingerprint Shell

To prevent the leakage of original biometric information of a user, it may be transformed into a cancelable form. A cancelable biometric transformation should satisfy four requirements: Unlinkability, revocability, noninvertibility, and performance. In 2014, Moujahdi et al. proposed a new cancelable fingerprint transformation called fingerprint shell, which was also later discussed by Ali et al. In this paper, we show that all of the shell fingerprint schemes presented by Moujahdi et al. and Ali et al. do not satisfy the condition of unlinkability.