Detailed Instantiation of the Decentralized Multi-Authority Anonymous Authentication Scheme and Tighter Reduction for Security

We give the details of the instantiation for the generic scheme of the decentralized multi-authority anonymous authentication (DMA-AAUTH) proposed in IACR Cryptology ePrint Archive. The instantiation is based on bilinear groups. Then, compared with the original security proof for the generic scheme, we give a security proof that is a tighter polynomial-time reduction for the instantiation by using the specific structure based on the bilinear groups. We evaluate the efficiency of the decentralized multi-authority attribute-based signature scheme (DMA-ABS) obtained by applying the Fiat-Shamir transform to our DMA-AAUTH scheme. Compared with the existing schemes, our DMA-ABS scheme attains shorter length of a signature on condition that the number of authorities is less than or equal to four.