In Proceedings of Asiacrypt 2010, vol. 6477 of LNCS, pages 519–38. Springer-Verlag, Dec. 2010.
Beginning with the work of Groth and Sahai, there has been much interest in transforming pairing-based schemes in composite-order groups to equivalent ones in prime-order groups. A method for achieving such transformations has recently been proposed by Freeman, who identified two properties of pairings using composite-order groups—“cancelling” and “projecting”—on which many schemes rely, and showed how either of these properties can be obtained using prime-order groups.
In this paper, we give evidence for the existence of limits to such transformations. Specifically, we show that a pairing generated in a natural way from the Decision Linear assumption in prime-order groups can be simultaneously cancelling and projecting only with negligible probability.
As evidence that these properties can be helpful together as well as individually, we present a cryptosystem whose proof of security makes use of a pairing that is both cancelling and projecting. Our example cryptosystem is a simple round-optimal blind signature scheme that is secure in the common reference string model, without random oracles, and based on mild assumptions; it is of independent interest.