Structure-Preserving Signatures on Equivalence Classes and Constant-Size Anonymous Credentials

摘要: Structure-preserving signatures (SPS) are a powerful building block for cryptographic protocols. We introduce SPS on equivalence classes (SPS-EQ), which allow joint randomization of messages and signatures. Messages projective defined group-element vectors, so multiplying vector by scalar yields different representative the same class. Our scheme lets one adapt signature to another without knowledge any secret. Moreover, given signature, an adapted is indistinguishable from fresh random message. propose definitional framework SPS-EQ efficient construction in Type-3 bilinear groups, we prove secure against generic forgers. also set-commitment schemes that let open subsets committed set. From this SPS-EQ, then build multi-show attribute-based anonymous credential system arbitrary number attributes. ABC avoids costly zero-knowledge proofs only requires short interactive proof thwart replay attacks. It first whose bandwidth required showing independent its attributes, i.e., constant-size. strengthened game-based security definitions our malicious organizations standard model; finally, discuss concurrently variant CRS model.