Accountable Authority Attribute-Based Signature

Since attribute-based signature (ABS) was introduced by Guo et al. in 2008, considerable researches have been done. In an ABS scheme, the attribute authority (A-authority) generates the private key for any users, hence it has to be completely trusted. The A-authority is free to engage in malicious activities without any risk of being confronted in a court of law. Motivated by this, we firstly propose a notion of accountable authority attribute-based signature scheme in this paper. It is not only a variant of ABS, but also a new approach to mitigate the key escrow problem. Then we construct an accountable authority attribute-based signature scheme. Finally we prove its security under the Computational Diffie-Hellman (CDH) and the Modified Computational Diffie-Hellman (MCDH) assumptions. Our main goal is to restrict the ways that the A-authority can misbehave. In our scheme, if the A-authority maliciously generates and distributes a private key, it will runs the risk of being caught and prosecuted.