Some weaknesses of “weaknesses of undeniable signatures”

Abstract

The weaknesses that are the subject of [DY 91] have already been addressed in the published literature [C 90 & CVA 89]. The main class of these weaknesses consists of ways of cheating undeniable signatures; but these ways are shown here to themselves be “weak.” Specifically, a cheater using them can double-cross the other cheaters, to the extent that the original ways of cheating are rendered useless. The remaining cited weaknesses are re-statements of, or variations on, some previously observed blinding techniques [CvA 89]. These techniques allow advantages in some applications when desired, but are also easily excluded when not desired.