Cryptology ePrint Archive: Report 2007/350

On Tweaking Luby-Rackoff Blockciphers

David Goldenberg and Susan Hohenberger and Moses Liskov and Elizabeth Crump Schwartz and Hakan Seyalioglu

Abstract: Tweakable blockciphers, first formalized by Liskov, Rivest, and Wagner, are blockciphers with an additional input, the tweak, which allows for variability. An open problem proposed by Liskov et al. is how to construct tweakable blockciphers without using a pre-existing blockcipher. This problem has yet to receive any significant study. There are many natural questions in this area: is it significantly more effcient to incorporate a tweak directly? How do direct constructions compare to existing techniques? Are these direct constructions optimal and for what levels of security? How large of a tweak can be securely added? In this work, we address these questions for Luby-Rackoff blockciphers. We show that tweakable blockciphers can be created directly from Feistel ciphers, and in some cases show that direct constructions of tweakable blockciphers are more e±cient than previously known constructions.

Category / Keywords: secret-key cryptography / block ciphers

Publication Info: Full version of paper in Asiacrypt 2007.

Date: received 6 Sep 2007

Contact author: mliskov at cs wm edu

Available format(s): Postscript (PS) | Compressed Postscript (PS.GZ) | BibTeX Citation

Version: 20070906:212248 (All versions of this report)

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