A fully collusion resistant public key trace and revoke scheme with dynamic registration and revocation

We present a new public key trace and revoke scheme, which is suitable for scenarios where users need to join or leave the system frequently. The proposed scheme supports public traceability and dynamic registration and revocation. It is also fully collusion resistant against adaptive chosen ciphertext attack, and its provable security is tightly reduced to the Decisional Diffie-Hellman (DDH) assumption in the standard model. No master key is needed in our scheme, and it allows users to generate public/private keys themselves and then submit the public keys to the system. This means that the setup phase only involves an authentic channel instead of a secure one. Therefore, our scheme can take advantage of Public key infrastructure (PKI) with Certificate authority (CA) playing the role of the system center.