On the Security of the Lee-Chang Group Signature Scheme and Its Derivatives
W.-B. Lee and C.-C. Chang (1998) proposed a very efficient group signature scheme based on the discrete logarithm problem. This scheme was subsequently improved by Y.-M. Tseng and J.-K. Jan (1999) so that the resulting group signatures are unlinkable. In this paper, we show that any obvious attempt to make unlinkable the Lee-Chang signatures would likely fail. More importantly, we show that both the original Lee-Chang signature scheme and its improved version are universally forgeable.
KeywordsDigital signatures Group signatures Cryptanalysis
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