Smooth Zero-Knowledge Hash Functions

Behzad Abdolmaleki, Hamidreza Khoshakhlagh, Helger Lipmaa

Research output: Contribution to book/anthology/report/proceedingArticle in proceedingsResearchpeer-review


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.

Original languageEnglish
Title of host publicationProgress in Cryptology – INDOCRYPT 2021 - 22nd International Conference on Cryptology in India, 2021, Proceedings : 22nd International Conference on Cryptology in India, Jaipur, India, December 12-15, 2021, Proceedings
EditorsAvishek Adhikari, Ralf Küsters, Bart Preneel
Number of pages26
Publication date2021
ISBN (Print)978-3-030-92517-8
Publication statusPublished - 2021
Event22nd International Conference on Cryptology in India - The LNM Institute of Information Technology, Jaipur, India
Duration: 13 Dec 202115 Dec 2021
Conference number: 22


Conference22nd International Conference on Cryptology in India
LocationThe LNM Institute of Information Technology
Internet address
SeriesLecture Notes in Computer Science


  • Plain model
  • RPK model
  • SPHF
  • Subversion zero-knowledge
  • Trapdoor SPHF


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