Research on Application of Packet Encryption Technology in Information Security Algorithm

As the focus of the development of the whole society in the era of big data, information security is also the main direction of the practice and development of technological innovation. On the basis of understanding the current information transmission security and its algorithm research, this paper analyzes how to use this technology to guarantee information security according to the block encryption principle.

DYNAMIC SUBSTITUTION BOXES OF SYMMETRIC BLOCK ENCRYPTION ALGORITHMS

The paper deals with nonlinear transformations of well-known symmetric block algorithms such as AES, Kuznyechik, SM4, BelT, and Kalyna. A brief description of the substitution boxes for these algorithms is given. The properties of nonlinearity of the described substitution boxes are investigated with the calculation of the corresponding values. Based on the property of nonlinearity, a method for generating a dynamic substitution box is proposed. The purpose of this method is to generate dynamic substitution boxes (S-boxes) that change depending on the values of some parameter obtained from the secret key of the algorithm. Considering that linear and differential cryptanalysis uses known substitution boxes, the main advantage of the new method is that S-boxes are randomly key-dependent and unknown. Experiments were also carried out to implement this method. The resulting dynamic substitution boxes were tested for nonlinearity and the results were compared with the original nonlinearity values of the same substitution boxes.

THE ALGORITHM OF BLOCK ENCRYPTION "AL03" AND THE RESULTS OF ITS ANALYSIS

This paper provides a brief description of the developed block cipher algorithm "AL03" and the results of checking the avalanche effect. This algorithm has the structure of a substitution-permutation network. The check consisted of two stages. At the first stage, the avalanche effect was tested separately for each transformation used in the algorithm. At the second stage, each round of encryption was analyzed. To characterize the degree of the avalanche effect in a transformation, the avalanche parameter is determined and used - the numerical value of the deviation of the probability of changing a bit in the output sequence when a bit in the input sequence changes from the required probability value equal to 0.5. The article presents the results after the 1st, 2nd, 3rd, and 24th rounds in the form of a table. Based on the round results obtained, comparative tests were carried out, as a result of which a positive conclusion was given on further research of this encryption algorithm.

A Novel Lightweight Block Encryption Algorithm Based on Combined Chaotic S-Box

Due to high computational cost, traditional encryption algorithms are not suitable for the environments in which resources are limited. In view of the above problem, we first propose a combined chaotic map to increase the chaotic interval and Lyapunov exponent of the existing one-dimensional chaotic maps. Then, an S-box based on the proposed combined chaotic map is constructed. The performances of the designed S-box, such as bijection, nonlinearity, strict avalanche criteria, differential uniformity, the bits independence criterion, and the linear approximation probability, are tested to show that it has better cryptographic performances. Finally, we present a lightweight block encryption algorithm by using the above S-box. The algorithm is based on the generalized Feistel structure and SPN structure. In addtion, the processes of encryption and decryption of our algorithm are almost the same, which reduces the complexity of algorithm implementation. The experimental results show that the proposed encryption algorithm meets the requirements of lightweight algorithms and has good cryptographic characteristics.