Multidimensional Extension of Matsui's Algorithm 2

Matsui’s one-dimensional Alg. 2 can be used for recovering bits of the last round key of a block cipher. In this paper a truly multidimensional extension of Alg. 2 based on established statistical theory is presented. Two possible methods, an optimal method based on the log-likelihood ratio and a χ2 -based goodness-of-fit test are compared in theory and by practical experiments on reduced round Serpent. The theory of advantage by Selc¸uk is generalised in multiple dimensions and the advantages and data, time and memory complexities for both methods are derived.

• Type: Conference
• Year: 2009
• Where: FSE
• Authors: Miia Hermelin, Joo Yeon Cho, Kaisa Nyberg
• Keywords: Block Cipher, Cryptography, FSE 2009, Matsui’s One-dimensional Alg, Statistical Theory