Cryptology ePrint Archive: Report 2019/1427

On the Relationship between Resilient Boolean Functions and Linear Branch Number of S-boxes

Sumanta Sarkar and Kalikinkar Mandal and Dhiman Saha

Abstract: Differential branch number and linear branch number are critical for the security of symmetric ciphers. The recent trend in the designs like PRESENT block cipher, ASCON authenticated encryption shows that applying S-boxes that have nontrivial differential and linear branch number can significantly reduce the number of rounds. As we see in the literature that the class of 4 x 4 S-boxes have been well-analysed, however, a little is known about the n x n S-boxes for n >= 5. For instance, the complete classification of 5 x 5 affine equivalent S-boxes is still unknown. Therefore, it is challenging to obtain “the best” S-boxes with dimension >= 5 that can be used in symmetric cipher designs. In this article, we present a novel approach to construct S-boxes that identifies classes of n x n S-boxes (n = 5, 6) with differential branch number 3 and linear branch number 3, and ensures other cryptographic properties. To the best of our knowledge, we are the first to report 6 x 6 S-boxes with linear branch number 3, differential branch number 3, and with other good cryptographic properties such as nonlinearity 24 and differential uniformity 4.

Category / Keywords: secret-key cryptography / S-box, Resilient Boolean function, linear branch number, differential branch number, nonlinearity, differential uniformity, lightweight cipher.

Original Publication (in the same form): Indocrypt 2019

Date: received 8 Dec 2019

Contact author: sumanta sarkar1 at tcs com

Available format(s): PDF | BibTeX Citation

Version: 20191210:080417 (All versions of this report)

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