International Association for Cryptologic Research

International Association
for Cryptologic Research


Weakly Secure Equivalence-Class Signatures from Standard Assumptions

Georg Fuchsbauer
Romain Gay
DOI: 10.1007/978-3-319-76581-5_6
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Conference: PKC 2018
Abstract: Structure-preserving signatures on equivalence classes, or equivalence-class signatures for short (EQS), are signature schemes defined over bilinear groups whose messages are vectors of group elements. Signatures are perfectly randomizable and given a signature on a vector, anyone can derive a signature on any multiple of the vector; EQS thus sign projective equivalence classes. Applications of EQS include the first constant-size anonymous attribute-based credentials, efficient round-optimal blind signatures without random oracles and efficient access-control encryption.To date, the only existing instantiation of EQS is proven secure in the generic-group model. In this work we show that by relaxing the definition of unforgeability, which makes it efficiently verifiable, we can construct EQS from standard assumptions, namely the Matrix-Diffie-Hellman assumptions. We then show that our unforgeability notion is sufficient for most applications.
  title={Weakly Secure Equivalence-Class Signatures from Standard Assumptions},
  booktitle={Public-Key Cryptography – PKC 2018},
  series={Public-Key Cryptography – PKC 2018},
  author={Georg Fuchsbauer and Romain Gay},