Biblio
In this paper, we propose the first identity-based broadcast encryption scheme, which can simultaneously achieves confidentiality and full anonymity against adaptive chosen-ciphertext attacks under a standard assumption. In addition, two further desirable features are also provided: one is fully-collusion resistant which means that even if all users outside of receivers S collude they cannot obtain any information about the plaintext. The other one is stateless which means that the users in the system do not need to update their private keys when the other users join or leave our system. In particular, our scheme is highly efficient, where the public parameters size, the private key size and the decryption cost are all constant and independent to the number of receivers.
The anonymous password authentication scheme proposed in ACSAC'10 under an unorthodox approach of password wrapped credentials advanced anonymous password authentication to be a practically ready primitive, and it is being standardized. In this paper, we improve on that scheme by proposing a new method of "public key suppression" for achieving server-designated credential verifiability, a core technicality in materializing the concept of password wrapped credential. Besides better performance, our new method simplifies the configuration of the authentication server, rendering the resulting scheme even more practical. Further, we extend the idea of password wrapped credential to biometric wrapped credential\vphantom\\, to achieve anonymous biometric authentication. As expected, biometric wrapped credentials help break the linear server-side computation barrier intrinsic in the standard setting of biometric authentication. Experimental results validate the feasibility of realizing efficient anonymous biometric authentication.