1 research outputs found
Analysis and Improvement of Authenticatable Ring Signcryption Scheme
Ring signcryption is an anonymous signcryption which allows a user
to anonymously signcrypt a message on behalf of a set of users
including himself. In an ordinary ring signcryption scheme, even if
a user of the ring generates a signcryption, he also cannot prove
that the signcryption was produced by himself. In 2008, Zhang, Yang,
Zhu, and Zhang solve the problem by introducing an identity-based
authenticatable ring signcryption scheme (denoted as the ZYZZ
scheme). In the ZYZZ scheme, the actual signcrypter can prove that
the ciphertext is generated by himself, and the others cannot
authenticate it. However, in this paper, we show that the ZYZZ
scheme is not secure against chosen plaintext attacks. Furthermore,
we propose an improved scheme that remedies the weakness of the ZYZZ
scheme. The improved scheme has shorter ciphertext size than the
ZYZZ scheme. We then prove that the improved scheme satisfies
confidentiality,
unforgeability, anonymity and authenticatability