A signature scheme associated with universal re-signcryption

Today, with increasing deversity of network technologies, people have been likely to be insterested in anonymity. The attacker might threaten anonymity of senders and receivers by confirming linkability between their sessions. Recently, Golle et al. proposed the re-encryption scheme applicable to Mix, called Universal Re-encryption. In this scheme, a ciphertext is supposed to be re-encrypted without public information corresponding to it. Moreover, only a subject that re-enctypts a ciphertext can know the correspondence of original ciphertext and it, and the computational complexity to break the unlinkability property is equal to the semantic secrecy. In this paper, we consider and improve the Universal Re-encryption scheme, and propose a scheme that can verify who transmit the message by adding the property of signature.