Delegatable Multi-Authority Attribute-Based Anonymous Credentials

In cloud computing, users need to authenticate to access various resources. Attribute-based anonymous credentials (ABCs) provide a tool for privacy-preserving authentication, allowing users to prove possession of a set of attributes to cloud service providers anonymously. Most existing works on ABC deal with credentials on attributes issued by a single authority (issuer). In reality, it is more practical for users to obtain credentials on attributes from multiple authorities. There are a few works on multi-authority ABC, which do not support delegation needed in real deployments. In this article, we present the first delegatable multi-authority attribute-based anonymous credential system, which simultaneously achieves revocation and traceability. We also give the security analysis of our construction. Finally, we implement our system, and the experimental results show its efficiency.