Efficient self-certified proxy CAE scheme and its variants

Elaborating on the merits of proxy signature schemes and convertible authenticated encryption (CAE) schemes, we adopt self-certified public key systems to construct efficient proxy CAE schemes enabling an authorized proxy signer to generate an authenticated ciphertext on behalf of the original signer. To satisfy the requirement of confidentiality, only the designated recipient is capable of decrypting the ciphertext and verifying the proxy signature. A significant advantage of the proposed schemes is that the proxy signature conversion process takes no extra cost, i.e., when the case of a later dispute over repudiation occurs, the designated recipient can easily reveal the ordinary proxy signature for the public arbitration. If needed, the designated recipient can also convince anyone that he is the real recipient. In addition, integrating with self-certified public key systems, our schemes can earn more computational efficiency, since authenticating the public key and verifying the proxy signature can be simultaneously carried out within one-step.