Group to group commitments do not shrink

  • Authors:
  • Masayuki Abe;Kristiyan Haralambiev;Miyako Ohkubo

  • Affiliations:
  • NTT Information Sharing Platform Laboratories, Japan;New York University;Security Architecture Laboratory, NSRI, NICT, Japan

  • Venue:
  • EUROCRYPT'12 Proceedings of the 31st Annual international conference on Theory and Applications of Cryptographic Techniques
  • Year:
  • 2012

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Abstract

We investigate commitment schemes whose messages, keys, commitments, and decommitments are elements of bilinear groups, and whose openings are verified by pairing product equations. Such commitments facilitate efficient zero-knowledge proofs of knowledge of a correct opening. We show two lower bounds on such schemes: a commitment cannot be shorter than the message and verifying the opening in a symmetric bilinear group setting requires evaluating at least two independent pairing product equations. We also present optimal constructions that match the lower bounds in symmetric and asymmetric bilinear group settings.