A framework for universally composable non-committing blind signatures

A universally composable (UC) blind signature functionality demands users to commit to the message to be blindly signed. It is thereby impossible to realize in the plain model. We show that even non-committing variants of UC blind signature functionality remain not realizable in the plain model. We then characterize adaptively secure UC non-committing blind signatures in the common reference string model by presenting equivalent stand-alone security notions. We also present a generic construction based on conceptually simple Fischlin's blind signature scheme.