A new mode of operation for block ciphers and length-preserving MACs

Yevgeniy Dodis, Krzysztof Pietrzak, Prashant Puniya

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

Abstract

We propose a new mode of operation, enciphered CBC, for domain extension of length-preserving functions (like block ciphers), which is a variation on the popular CBC mode of operation. Our new mode is twice slower than CBC, but has many (property-preserving) properties not enjoyed by CBC and other known modes. Most notably, it yields the first constant-rate Variable Input Length (VIL) MAC from any length preserving Fixed Input Length (FIL) MAC. This answers the question of Dodis and Puniya from Eurocrypt 2007. Further, our mode is a secure domain extender for PRFs (with basically the same security as encrypted CBC). This provides a hedge against the security of the block cipher: if the block cipher is pseudorandom, one gets a VIL-PRF, while if it is "only" unpredictable, one "at least" gets a VIL-MAC. Additionally, our mode yields a VIL random oracle (and, hence, a collision-resistant hash function) when instantiated with length-preserving random functions, or even random permutations (which can be queried from both sides). This means that one does not have to re-key the block cipher during the computation, which was critically used in most previous constructions (analyzed in the ideal cipher model).

Original languageEnglish (US)
Title of host publicationAdvances in Cryptology - EUROCRYPT 2008 - 27th Annual International Conference on the Theory and Applications of Cryptographic Techniques, Proceedings
Pages198-219
Number of pages22
DOIs
StatePublished - Jun 5 2008
Event27th Annual International Conference on the Theory and Applications of Cryptographic Techniques, EUROCRYPT 2008 - Istanbul, Turkey
Duration: Apr 13 2008Apr 17 2008

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume4965 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Other

Other27th Annual International Conference on the Theory and Applications of Cryptographic Techniques, EUROCRYPT 2008
CountryTurkey
CityIstanbul
Period4/13/084/17/08

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ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)

Cite this

Dodis, Y., Pietrzak, K., & Puniya, P. (2008). A new mode of operation for block ciphers and length-preserving MACs. In Advances in Cryptology - EUROCRYPT 2008 - 27th Annual International Conference on the Theory and Applications of Cryptographic Techniques, Proceedings (pp. 198-219). (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics); Vol. 4965 LNCS). https://doi.org/10.1007/978-3-540-78967-3_12