A Framework for UC-Secure Commitments from Publicly Computable Smooth Projective Hashing

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  • Behzad Abdolmaleki, University of Tartu
  • ,
  • Hamidreza Khoshakhlagh
  • Daniel Slamanig, Austrian Institute of Technology

Hash proof systems or smooth projective hash functions (SPHFs) have been proposed by Cramer and Shoup (Eurocrypt’02) and can be seen as special type of zero-knowledge proof system for a language. While initially used to build efficient chosen-ciphertext secure public-key encryption, they found numerous applications in several other contexts. In this paper, we revisit the notion of SPHFs and introduce a new feature (a third mode of hashing) that allows to compute the hash value of an SPHF without having access to neither the witness nor the hashing key, but some additional auxiliary information. We call this new type publicly computable SPHFs (PC-SPHFs) and present a formal framework along with concrete instantiations from a large class of SPHFs. We then show that this new tool generically leads to commitment schemes that are secure against adaptive adversaries, assuming erasures in the Universal Composability (UC) framework, yielding the first UC secure commitments build from a single SPHF instance. Instantiating our PC-SPHF with an SPHF for labeled Cramer-Shoup encryption gives the currently most efficient non-interactive UC-secure commitment. Finally, we also discuss additional applications to information retrieval based on anonymous credentials being UC secure against adaptive adversaries.

Original languageEnglish
Title of host publicationCryptography and Coding - 17th IMA International Conference, IMACC 2019, Proceedings
EditorsMartin Albrecht
Number of pages21
PublisherSpringer
Publication year2019
Pages1-21
ISBN (print)9783030351984
DOIs
Publication statusPublished - 2019
Event17th IMA International Conference on Cryptography and Coding, IMACC 2019 - Oxford, United Kingdom
Duration: 16 Dec 201918 Dec 2019

Conference

Conference17th IMA International Conference on Cryptography and Coding, IMACC 2019
LandUnited Kingdom
ByOxford
Periode16/12/201918/12/2019
SeriesLecture Notes in Computer Science
Volume11929
ISSN0302-9743

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