An anonymous credential system and a privacy-aware PKI

In this paper we present a non-transferable anonymous credential system that is based on the concept of a chameleon certificate. A chameleon certificate is a special certificate that enjoys two interesting properties. Firstly, the owner can choose which attributes of the certificate to disclose. Moreover, a chameleon certificate is multi-show in the sense that several uses of the same chameleon certificate by the same user cannot be linked together. We adopt the framework of Brands [2] and our construction improves the results of Camenisch et al. [5] and Verheul [16] since it allows the owner of a certificate to prove general statements on the attributes encoded in the certificate and our certificates enjoy the multi-show property.