On the Security of the Lee-Hwang Group-Oriented: Undeniable Signature Schemes

• Autores: Guilin Wang, Jianying Zhou, Robert H. Deng
• Localización: Trust and Privacy in Digital Business: First International Conference,TrustBus 2004 Zaragoza, Spain, August 30 - September 1, 2004 Proceedings / coord. por Sokratis Katsikas, Günther Pernul, Javier López, 2004, ISBN 3540229191, págs. 289-298
• Idioma: español
• Texto completo no disponible (Saber más ...)
• Resumen

  • Undeniable signature is an intriguing concept introduced by Chaum and van 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 effective attacks on their schemes: four of them are insider universal forgeries, in which one dishonest member (maybe colluding 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. We also suggest heuristic improvements to overcome some of the problems involved in these attacks.