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COMCOM
1999

Group-oriented undeniable signature schemes with a trusted center

13 years 6 months ago
Group-oriented undeniable signature schemes with a trusted center
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.
Narn-Yih Lee, Tzonelih Hwang
Added 22 Dec 2010
Updated 22 Dec 2010
Type Journal
Year 1999
Where COMCOM
Authors Narn-Yih Lee, Tzonelih Hwang
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