Tweakable enciphering schemes from hash-sum-expansion

Kazuhiko Minematsu*, Toshiyasu Matsushima

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

16 Citations (Scopus)


We study a tweakable blockcipher for arbitrarily long message (also called a tweakable enciphering scheme) that consists of a universal hash function and an expansion, a keyed function with short input and long output. Such schemes, called HCTR and HCH, have been recently proposed. They used (a variant of) the counter mode of a blockcipher for the expansion. We provide a security proof of a structure that underlies HCTR and HCH. We prove that the expansion can be instantiated with any function secure against Known-plaintext attacks (KPAs), which is called a weak pseudorandom function (WPRF). As an application of our proof, we provide efficient blockcipher-based schemes comparable to HCH and HCTR. For the double-block-length case, our result is an interesting extension of previous attempts to build a doubleblock-length cryptographic permutation using WPRF.

Original languageEnglish
Title of host publicationProgress in Cryptology - INDOCRYPT 2007 - 8th International Conference on Cryptology in India, Proceedings
Number of pages16
Publication statusPublished - 2007 Dec 1
Event8th Annual International Conference on Cryptolology in India, INDOCRYPT 2007 - Chennai, India
Duration: 2007 Dec 92007 Dec 13

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume4859 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference8th Annual International Conference on Cryptolology in India, INDOCRYPT 2007


  • HCH
  • HCTR
  • Mode of operation
  • Weak pseudorandom function

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)


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