Method and device for realizing S box in SM4 algorithm

Abstract

The invention provides a method for realizing an S box in an SM4 algorithm, which comprises the following steps: performing first affine transformation and isomorphic transformation on an input element of the S box in a finite field GF (28) to obtain an element in a composite field; decomposing the inverse multiplication operation of the element in the composite domain into inverse operation and multiplication operation on GF (24), performing inverse operation on GF (24) on a polynomial ring base, and performing multiplication operation on GF (24) on a redundant representation base to obtain an inverse element on the composite domain; and performing inverse isomorphic transformation and second affine transformation on the inverse element in the composite domain to obtain an output result of the S box. Calculation of the S box is carried out on the basis of corresponding high efficiency, so that the structure of the S box is more compact and efficient, and the circuit area and time delay of the S box in the SM4 algorithm are further reduced.

Description

technical field [0001] The present invention relates to the technical field of cryptographic algorithm hardware implementation, and more specifically, to a method and device for implementing an S-box in an SM4 algorithm. Background technique [0002] SM4 is a block cipher algorithm used by wireless LAN products. It was approved by the State Cryptography Administration in 2006 and is the first commercial cipher algorithm officially announced in China. With the development of the standardization of cryptographic algorithms in my country, the SM4 algorithm was released in March 2012 as the national cryptographic industry standard. It was released as a national standard in August 2016. [0003] The only nonlinear computing unit in SM4 is the S-box, which is used in key expansion and round functions, so it has a great impact on the circuit area of ​​the entire SM4 algorithm. How to reduce the circuit area of ​​the S-box is particularly important. Some related optimization metho...

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Problems solved by technology

[0003] The only nonlinear computing unit in SM4 is the S-box, which is used in key expansion and round functions, so it has a great impact on the circuit area of ​​the entire SM4 algorithm. How to reduce the circuit area of ​​the S-box is particularly important. Some related optimization methods use the isomorphic mapping method based on the compound field, and put the S box in the finite field GF(2 8 ) in the form of non-redundant bases such as polynomial bases or normal bases. This representation method brings a certain degree of optimization, but the calculation is still relatively complicated, and the S-box requires a large number of equivalent and non-redundant bases. gate, consumes more circuit area

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