This paper presents a new practical key-length extension scheme exhibiting k + n/2 bits of security – hence improving upon the security of triple encryption – solely at the cost of two block cipher calls and a key of length k + n. We also provide matching generic attacks showing the optimality of the security level achieved by our approach with respect to a general class of two-query constructions.
Category / Keywords: secret-key cryptography / Block ciphers, Cascade encryption, Provable security. Publication Info: A preliminary version of this paper appears in the proceedings of EUROCRYPT 2012. This is the full version. Date: received 23 Mar 2012, last revised 24 Mar 2012 Contact author: peter gazi at inf ethz ch Available formats: PDF | BibTeX Citation Version: 20120324:064137 (All versions of this report) Discussion forum: Show discussion | Start new discussion