Privacy Protection in PKIs: A Separation-of-Authority Approach

Due to the growing number of privacy infringement problems, there are increasing demands for privacy enhancing techniques on the Internet. In the PKIs, authorized entities such as CA and RA may become, from the privacy concerns, a big brother even unintentionally since they can always trace the registered users with regard to the public key certificates. In this paper, we investigate a practical method for privacy protection in the existing PKIs by separating the authorities, one for verifying ownership and the other for validating contents, in a blinded manner. The proposed scheme allows both anonymous and pseudonymous certificates to be issued and used in the existing infrastructures in the way that provides conditional traceability and revocability based on the threshold cryptography and selective credential show by exploiting the extension fields of X.509 certificate version 3.

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