Paper 2021/1565

Practical, Round-Optimal Lattice-Based Blind Signatures

Shweta Agrawal, IIT Madras
Elena Kirshanova, I.Kant Baltic Federal University, Technology Innovation Institute
Damien Stehle
Anshu Yadav, IIT Madras

Blind signatures are a fundamental cryptographic primitive with numerous practical applications. While there exist many practical blind signatures from number-theoretic assumptions, the situation is far less satisfactory from post-quantum assumptions. In this work, we provide the first overall practical, lattice-based blind signature, supporting an unbounded number of signature queries and additionally enjoying optimal round complexity. We provide a detailed estimate of parameters achieved -- we obtain a signature of size slightly above 45KB, for a core-SVP hardness of 109 bits. The run-times of the signer, user and verifier are also very small. Our scheme relies on the Gentry, Peikert and Vaikuntanathan signature [STOC'08] and non-interactive zero-knowledge proofs for linear relations with small unknowns, which are significantly more efficient than their general purpose counterparts. Its security stems from a new and arguably natural assumption which we introduce, called the one-more-ISIS assumption. This assumption can be seen as a lattice analogue of the one-more-RSA assumption by Bellare et al [JoC'03]. To gain confidence in our assumption, we provide a detailed analysis of diverse attack strategies.

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Public-key cryptography
Publication info
Published elsewhere. ACM CCS 2022
Blind signatures practical round-optimal lattices
Contact author(s)
shweta a @ cse iitm ac in
elenakirshanova @ gmail com
damien stehle @ ens-lyon fr
anshu yadav06 @ gmail com
2022-09-02: last of 3 revisions
2021-12-02: received
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      author = {Shweta Agrawal and Elena Kirshanova and Damien Stehle and Anshu Yadav},
      title = {Practical, Round-Optimal Lattice-Based Blind Signatures},
      howpublished = {Cryptology ePrint Archive, Paper 2021/1565},
      year = {2021},
      note = {\url{}},
      url = {}
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