Round Optimal Blind Signatures

Round Optimal Blind Signatures (Crypto 2011)
Dominique Schröder, Dominique Unruh, Sanjam Garg, Vanishree Rao, Amit Sahai
[ official ]

Constructing round-optimal blind signatures in the standard model has been a long standing open problem. In particular, Fischlin and Schröder recently ruled out a large class of three-move blind signatures in the standard model (Eurocrypt’10). In particular, their result shows that finding security proofs for the well-known blind signature schemes by Chaum, and by Pointcheval and Stern in the standard model via black-box reductions is hard. In this work we propose the first round-optimal, i.e., two-move, blind signature scheme in the standard model (i.e., without assuming random oracles or the existence of a common reference string). Our scheme relies on the Decisional Diffie Hellman assumption and the existence of sub-exponentially hard 1-to-1 one way functions. This scheme is also secure in the concurrent setting.

Merger of [CITE 2roundbs-orig] and “Round Optimal Blind Signatures in the Standard Model” by Sanjam Garg, Vanishree Rao, and Amit Sahai.