文摘
Anonymous authentication is very useful to protect the users’ identity privacy in distributed environment, such as in cloud computing. With the anonymous property, attribute-based signature (ABS) provides a cryptographic tool to construct a secure authentication scheme. In an attribute-based signature scheme, a signer owning a set of attributes is able to sign anonymously message with regarding to a policy, while the signatures are kept unforgeable even in the case of collusion. In this paper, we provide a novel construction of key-policy ABS for general circuits. Our construction is based on the correlation-relaxed two-to-one recoding (CR-TOR), which can be instantiated from the existence of multilinear maps. Due to the key indistinguishability property of the CR-TOR system, we prove that our scheme is selective unforgeability in the standard model under the k-Multilinear Computational Diffie-Hellman (k-MCDH) assumption. At the same time, the proposed scheme also holds the property of perfect privacy. Our framework based on CR-TOR leads to a circuit-ABS scheme that is conceptually different from the existing construction in the multilinear maps setting.