Segmentation method based on S boxes

Abstract

The invention discloses a segmentation method based on S boxes. The segmentation method comprises the following contents: for a DES algorithm: replacing the S4 in an original algorithm with the S boxof the DESL or replacing all S boxes in the original algorithm with the S4 in the original algorithm; and for a CAST-128 algorithm: removing the "circulation key" operation of the original algorithm,and the operation of changing a "modulo plus key" and a "modulo minus key" into "exclusive or keys". Compared with the prior art, the differential analysis resistance of the DES algorithm is obviously improved after being replaced by the manner of the segmentation method disclosed by the invention. For the CAST-128 algorithm, the S box and the use sequence are modified, so that a new round function can resist the appearance of high-probability differential features with a probability of 2-7. Therefore, the modified algorithm can maintain the original differential analysis resistance and meanwhile can resist side channel attacks.

Description

technical field [0001] The invention relates to a segmentation method based on S-box. Background technique [0002] Differential analysis was first proposed by Biham and Shamir in 1990, and it has been widely used in the analysis of symmetric cryptographic algorithms. Therefore, the security of cryptographic algorithms can be evaluated by studying the ability of cryptographic algorithms to resist differential analysis. The current research results show that the choice of S-box affects the probability of differential routing and the number of propagation rounds, which in turn affects its ability to resist differential analysis. Since the design details of the S-box used in the traditional DES algorithm have not been disclosed temporarily, it is possible to replace the S-box to improve its ability to resist differential analysis. [0003] Side-channel attack is a means for attackers to obtain keys by observing the running time, power consumption, and electromagnetic radiation...

AI Technical Summary

Problems solved by technology

[0003] Side channel attack is a means for attackers to obtain keys by observing the running time, power consumption and electromagnetic radiation of the algorithm, while the traditional CAST-128 algorithm cannot resist side channel attacks

The general method of resisting side-channel attacks is mainly by adding noise in the algorithm (such as by adding random delay in the algorithm operation), making it difficult for the attacker to identify the internal key information, but this resistance method is difficult to give provable security The result; at present, the most effective design method against side-channel attacks is to use a masking mechanism, which is provably safe, but the masking mechanism will greatly reduce the execution efficiency of the algorithm, making it difficult to use on small-scale embedded devices. impractical to run

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