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Paper 2021/653

Smooth Zero-Knowledge Hash Functions

Behzad Abdolmaleki, Hamidreza Khoshakhlagh, and Helger Lipmaa

Abstract

We define smooth zero-knowledge hash functions (SZKHFs) as smooth projective hash functions (SPHFs) for which the completeness holds even when the language parameter lpar and the projection key HP were maliciously generated. We prove that blackbox SZKHF in the plain model is impossible even if lpar was honestly generated. We then define SZKHF in the registered public key (RPK) model, where both lpar and HP are possibly maliciously generated but accepted by an RPK server, and show that the CRS-model trapdoor SPHFs of Benhamouda et al. are also secure in the weaker RPK model. Then, we define and instantiate subversion-zero knowledge SZKHF in the plain model. In this case, both lpar and HP are completely untrusted, but one uses non-blackbox techniques in the security proof.

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
Preprint. MINOR revision.
Keywords
plain modelRPK modelSPHFtrapdoor SPHFsubversion zero-knowledge
Contact author(s)
hamidreza @ cs au dk
History
2021-05-20: received
Short URL
https://ia.cr/2021/653
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2021/653,
      author = {Behzad Abdolmaleki and Hamidreza Khoshakhlagh and Helger Lipmaa},
      title = {Smooth Zero-Knowledge Hash Functions},
      howpublished = {Cryptology {ePrint} Archive, Paper 2021/653},
      year = {2021},
      url = {https://eprint.iacr.org/2021/653}
}
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