International Association for Cryptologic Research

International Association
for Cryptologic Research


Efficient Fully Structure-Preserving Signatures and Shrinking Commitments

Masayuki Abe
Jens Groth
Markulf Kohlweiss
Miyako Ohkubo
Mehdi Tibouchi
DOI: 10.1007/s00145-018-9300-5
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Abstract: In structure-preserving signatures, public keys, messages, and signatures are all collections of source group elements of some bilinear groups. In this paper, we introduce fully structure-preserving signature schemes, with the additional requirement that even secret keys are group elements. This strong property allows efficient non-interactive proofs of knowledge of the secret key, which is useful in designing cryptographic protocols under simulation-based security where online extraction of the secret key is needed. We present efficient constructions under simple standard assumptions and pursue even more efficient constructions with the extra property of randomizability based on the generic bilinear group model. An essential building block for our efficient standard model construction is a shrinking structure-preserving trapdoor commitment scheme, which is by itself an important primitive and of independent interest as it appears to contradict a known impossibility result that structure-preserving commitments cannot be shrinking. We argue that a relaxed binding property lets us circumvent the impossibility while still retaining the usefulness of the primitive in important applications as mentioned above.
  title={Efficient Fully Structure-Preserving Signatures and Shrinking Commitments},
  journal={Journal of Cryptology},
  author={Masayuki Abe and Jens Groth and Markulf Kohlweiss and Miyako Ohkubo and Mehdi Tibouchi},