Paper 2021/806

Boosting the Security of Blind Signature Schemes

Jonathan Katz and Julian Loss and Michael Rosenberg

Abstract

Existing blind signature schemes that are secure for polynomially many concurrent executions of the signing protocol are either inefficient or rely on non-standard assumptions (even in the random-oracle model). We show the first efficient blind signature schemes achieving this level of security based on the RSA, factoring, or discrete logarithm assumptions (in the random-oracle model). Our core technique involves an extension and generalization of a transform due to Pointcheval (Eurocrypt '98) that allows us to convert certain blind signature schemes that are secure for (concurrently) issuing logarithmically many signatures into ones secure for (concurrently) issuing polynomially many signatures.