Anonymous public-key certificates for anonymous and fair document exchange

Two protocols are presented for the issuing and identity tracing of anonymous public-key certificates, used by different parties to engage in an anonymous and fair document exchange without revealing their real identities while still being held accountable for their activities. The certificate issuing protocol allows a party to apply to certificate authorities for anonymous public-key certificates using a certificate already issued. The identity tracing protocol enables a legal authority to trace the pseudonym in an anonymous certificate back to the real identity of the corresponding party. The protocols are also analysed with regard to anonymity and accountability