Cryptology ePrint Archive: Report 2016/1181
New Impossible Differential Search Tool from Design and Cryptanalysis Aspects
Yu Sasaki and Yosuke Todo
Abstract: In this paper, a new tool searching for impossible differentials
against symmetric-key primitives is presented. Compared to the previous tools, our tool can detect any contradiction between input and output differences, and it can take into account the property inside the S-box when its size is small e.g. 4 bits. In addition, several techniques are proposed to evaluate 8-bit S-box. With this tool, the number of rounds of impossible differentials are improved from the previous best results by 1 round for Midori128, Lilliput, and Minalpher. The tool also finds new impossible differentials of ARIA and MIBS. We manually verify the impossibility of the searched results, which reveals new structural properties of those designs.
Our tool can be implemented only by slightly modifying the previous differential search tool using Mixed Integer Linear Programming (MILP), while the previous tools need to be implemented independently of the differential search tools. This motivates us to discuss the usage of our tool particular for the design process. With this tool, the maximum number of rounds of impossible differentials can be proven under reasonable assumptions and the tool is applied to various concrete designs.
Category / Keywords: secret-key cryptography /
Date: received 27 Dec 2016
Contact author: sasaki yu at lab ntt co jp
Available format(s): PDF | BibTeX Citation
Version: 20161230:194730 (All versions of this report)
Short URL: ia.cr/2016/1181
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