The iterated Even-Mansour (EM) scheme is a generalization of the original 1-round construction proposed in 1991, and can use one key, two keys, or completely independent keys. In this paper, we methodically analyze the security of all the possible iterated Even-Mansour schemes with two n-bit keys and up to four rounds, and show that none of them provides more than n-bit security. Our attacks are based on a new cryptanalytic technique called multibridge which splits the cipher to different parts in a novel way, such that they can be analyzed independently, exploiting its self-similarity properties. After the analysis of the parts, the key suggestions are efficiently joined using a meet-in-themiddle procedure.
As a demonstration of the multibridge technique, we devise a new attack on 4 steps of the LED-128 block cipher, reducing the time complexity of the best known attack on this scheme from 296 to 264. Furthermore, we show that our technique can be used as a generic key-recovery tool, when combined with some statistical distinguishers (like those recently constructed in reflection cryptanalysis of GOST and PRINCE).
|Title of host publication||Advances in Cryptology - ASIACRYPT 2014 - 20th International Conference on the Theory and Application of Cryptology and Information Security, Proceedings, Part I|
|Editors||Palash Sarkar, Tetsu Iwata|
|Number of pages||19|
|State||Published - 2014|
|Event||20th International Conference on the Theory and Application of Cryptology and Information Security, ASIACRYPT 2014 - Kaoshiung, Taiwan, Province of China|
Duration: 7 Dec 2014 → 11 Dec 2014
|Name||Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)|
|Conference||20th International Conference on the Theory and Application of Cryptology and Information Security, ASIACRYPT 2014|
|Country/Territory||Taiwan, Province of China|
|Period||7/12/14 → 11/12/14|
Bibliographical notePublisher Copyright:
© International Association for Cryptologic Research 2014.
- Iterated even-mansour
- Meet-in-the-middle attacks
- Multibridge attack
ASJC Scopus subject areas
- Theoretical Computer Science
- Computer Science (all)