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Paper: Cryptanalysis of the Lee-Hwang Group-Oriented Undeniable Signature Schemes

Authors: Guilin Wang Jianying Zhou Robert H. Deng URL: http://eprint.iacr.org/2002/150 Search ePrint Search Google Undeniable signature is an intriguing concept introduced by Chaum and Antwerpen at Crypto'89. In 1999, Lee and Hwang presented two group-oriented undeniable signature schemes with a trusted center. Their schemes are natural generalizations of Chaum's zero-knowledge undeniable signature scheme proposed in 1990. However, we find that the Lee-Hwang schemes are insecure. In this paper, we demonstrate five attacks on their schemes: four of them are universal forgery, in which one dishonest member (maybe collude with a verifier) can get a valid signature on any chosen massage, and another attack allows a dishonest member to prevent honest members from generating valid signatures but his cheating behavior is undetected. We also suggest heuristic improvements to overcome some of the problems involved in these attacks.
BibTeX
@misc{eprint-2002-11673,
title={Cryptanalysis of the Lee-Hwang Group-Oriented Undeniable Signature Schemes},
booktitle={IACR Eprint archive},
keywords={public-key cryptography / digital signatures, undeniable signatures, cryptanalysis},
url={http://eprint.iacr.org/2002/150},
note={Technical Report glwang@lit.a-star.edu.sg 11960 received 29 Sep 2002},
author={Guilin Wang and Jianying Zhou and Robert H. Deng},
year=2002
}