Tweakable Blockciphers with Asymptotically Optimal Security

Rodolphe Lampe; Yannick Seurin

Paper 2015/182

Tweakable Blockciphers with Asymptotically Optimal Security

Rodolphe Lampe and Yannick Seurin

Abstract

We consider tweakable blockciphers with beyond the birthday bound security. Landecker, Shrimpton, and Terashima (CRYPTO 2012) gave the first construction with security up to $O (2^{2 n / 3})$ adversarial queries ( $n$ denotes the block size in bits of the underlying blockcipher), and for which changing the tweak does not require changing the keys for blockcipher calls. In this paper, we extend this construction, which consists of two rounds of a previous proposal by Liskov, Rivest, and Wagner (CRYPTO 2002), by considering larger numbers of rounds $r > 2$ . We show that asymptotically, as $r$ increases, the resulting tweakable blockcipher approaches security up to the information bound, namely $O (2^{n})$ queries. Our analysis makes use of a coupling argument, and carries some similarities with the analysis of the iterated Even-Mansour cipher by Lampe, Patarin, and Seurin (ASIACRYPT 2012).

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: Published by the IACR in FSE 2013
DOI: 10.1007/978-3-662-43933-3_8
Keywords: tweakable blockcipher beyond birthday bound coupling message authentication code
Contact author(s): rodolphe lampe @ gmail com
yannick seurin @ m4x org
History: 2015-03-04: received
Short URL: https://ia.cr/2015/182
License: CC BY

BibTeX

@misc{cryptoeprint:2015/182,
      author = {Rodolphe Lampe and Yannick Seurin},
      title = {Tweakable Blockciphers with Asymptotically Optimal Security},
      howpublished = {Cryptology {ePrint} Archive, Paper 2015/182},
      year = {2015},
      doi = {10.1007/978-3-662-43933-3_8},
      url = {https://eprint.iacr.org/2015/182}
}