We construct the first blind signature scheme that achieves all of the following properties simultaneously: The third property enables a reasonably efficient solution, and in fact signatures in our scheme comprise 10 group elements and 29 \(\mathbb {Z} _p\) -elements. Our scheme starts from a pairing-based non-blind signature scheme (Abe et al., JoC 2023), and uses recent techniques of Chairattana-Apirom, Tessaro, and Zhu (CRYPTO 2024) to replace the pairings used in this scheme with non-interactive zero-knowledge proofs in the random oracle model. This conversion is not generic or straightforward (also because prior works have converted only significantly simpler signature schemes), and we are required to improve upon and innovate existing techniques in several places. As an interesting side note, and unlike previous works, our techniques only require a non-programmable random oracle, and our signature scheme achieves predicate blindness (which means that the user can prove statements about the signed message during the signing process).

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Tightly-Secure Blind Signatures in Pairing-Free Groups

  • Nicholas Brandt,
  • Dennis Hofheinz,
  • Michael Klooß,
  • Michael Reichle

摘要

We construct the first blind signature scheme that achieves all of the following properties simultaneously: The third property enables a reasonably efficient solution, and in fact signatures in our scheme comprise 10 group elements and 29 \(\mathbb {Z} _p\) -elements. Our scheme starts from a pairing-based non-blind signature scheme (Abe et al., JoC 2023), and uses recent techniques of Chairattana-Apirom, Tessaro, and Zhu (CRYPTO 2024) to replace the pairings used in this scheme with non-interactive zero-knowledge proofs in the random oracle model. This conversion is not generic or straightforward (also because prior works have converted only significantly simpler signature schemes), and we are required to improve upon and innovate existing techniques in several places. As an interesting side note, and unlike previous works, our techniques only require a non-programmable random oracle, and our signature scheme achieves predicate blindness (which means that the user can prove statements about the signed message during the signing process).