Nonlinear transformation method for symmetric key encryption and implementation method thereof

Abstract

The invention provides a nonlinear transformation method and a nonlinear transformation device for symmetric key encryption. Nonlinear transformation can be used directly as an S box; the S box uses function complex affine transformation in a finite field; and on the basis of keeping the original structure and code cryptographic characteristics of the S box of advanced encryption standard (AES), by increasing the times of nonlinear operation, the algebraic immunity of the S box is improved without reducing the complexity of the implementation mode of complex field hardware of the S box. The invention also provides a method for implementing the hardware of the S box. In the method, the complex field representation of elements is introduced, the inversion of an original field is converted into the inversion of a complex field, a plurality of linear and affine transformations are combined, and sub-field operations involved in the inversion of the complex field, such as multiplication, square operation, constant multiplication and inversion are all converted into inter-bit exclusive or operation and and operation. The whole S box hardware implementation process only requires a simple logic gate circuit, table lookup is avoided, hardware implement expense is reduced and the path delay is reduced.

Description

technical field [0001] The invention belongs to the field of information security, and in particular relates to the design of a non-linear transformation (S-box) in a block cipher algorithm and its composite domain hardware implementation. Background technique [0002] Information security involves the confidentiality, integrity and authentication of information. Among them, cryptographic theory is the basis of information security. Cryptographic algorithms are mainly divided into two categories: symmetric cryptographic algorithms and asymmetric cryptographic algorithms. A symmetric encryption algorithm means that the encryption key and the decryption key are the same, or knowing one of the keys is easy to derive the other key. Usually, the design of a symmetric cryptographic algorithm should not only consider the security strength of the algorithm, but also pay attention to the implementation performance of the algorithm: software implementation performance and hardware i...

AI Technical Summary

Problems solved by technology

However, the theoretical security of the algorithm and the actual implementation performance are often a pair of contradictions, how to find a balance point is a very complicated issue

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