Statement-Oblivious Threshold Witness Encryption

Sebastian Faust, Carmit Hazay, David Kretzler, Benjamin Schlosser

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


The notion of witness encryption introduced by Garg et al. (STOC'13) allows to encrypt a message under a statement $x$ from some NP-language $\mathcal{L}$ with associated relation $(x, w)\in \mathcal{R}$, where decryption can be carried out with the corresponding witness $w$. Unfortunately, known constructions for general-purpose witness encryption rely on strong assumptions, and are mostly of theoretical interest. To address these short-comings, Goyal et al. (PKC'22) recently introduced a blockchain-based alternative, where a committee decrypts ciphertexts when provided with a valid witness $w$. Blockchain-based committee solutions have recently gained broad interest to offer security against more powerful adversaries and construct new cryptographic primitives. We follow this line of work, and propose a new notion of statement-oblivious threshold witness encryption. Our new notion offers the functionality of committee-based witness encryption while additionally hiding the statement used for encryption. We present two ways to build statement-oblivious threshold witness encryption, one generic transformation based on anonymous threshold identity-based encryption (A-TIBE) and one direct construction based on bilinear maps. Due to the lack of efficient A-TIBE schemes, the former mainly constitutes a feasibility result, while the latter yields a concretely efficient scheme.

Original languageEnglish
Title of host publicationProceedings - 2023 IEEE 36th Computer Security Foundations Symposium, CSF 2023
PublisherIEEE Computer Society
Number of pages16
ISBN (Electronic)9798350321920
StatePublished - 2023
Event36th IEEE Computer Security Foundations Symposium, CSF 2023 - Haifa, Israel
Duration: 9 Jul 202313 Jul 2023

Publication series

NameProceedings - IEEE Computer Security Foundations Symposium
ISSN (Print)1940-1434


Conference36th IEEE Computer Security Foundations Symposium, CSF 2023

Bibliographical note

Publisher Copyright:
© 2023 IEEE.


  • Committee-Based Decryption
  • Statement Obliviousness
  • Threshold Tag-Based Encryption
  • Threshold Witness Encryption


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