SYMMETRIC CRYPTOSYSTEM WITH NONLINEAR ENCRYPTION AND THE POSSIBILITY OF CONTROL OF CIPHERTEXT FOR CONCEALMENT
V.M. Dzhuliy, I.V. Mulyar, В.С. Орленко, Віра ТІТОВА, Volodymyr Anikin · Herald of Khmelnytskyi National University Technical sciences · 2020
The article proposes a simple symmetric permutation cryptosystem, in which permutations occur based on streaming generation of random numbers. Substitution-permutation algorithms are quite common today. They have proven to be reliable crypto-strong ciphers that have seriously competed with iterative mathematical ciphers, based on the Feistel network, and are gradually displacing them more and more, taking their place. The aim of the article is to propose an encryption algorithm that has a simple structure and is easy to implement. At the same time, it is estimated to be quite resistant to crypto attacks. This encryption algorithm has a high speed and uses all the advantages of permutation encryption algorithms. Developed an encryption scheme in which permutations occur randomly, and as a result, a situation becomes possible when one plaintext with the same key corresponds to many ciphertexts, which seriously complicates the work of cryptanalysts, complicating the analysis and cracking of the cipher, and significantly increases the scope of application of this cryptosystem. Also, this cryptosystem has steganographic potential, because the nonlinearity that creates the variability of ciphertexts, allows the same byte to encrypt dozens or even hundreds of combinations. This paper has clearly shown a new approach to the creation of encryption variability and random selection is proposed. It makes possible to modify existing encryption algorithms.