Abstract
Nowadays the development of information technologies bring to cryptologists not only opportunities to solve the most difficult cryptography classical tasks, also they give capacity to hacked well-known cryptosystems. Therefore, applying other areas of mathematical for modifications of information security methods is relevant task of research in cryptography. The theory of automata was considered as an alternative model for creating high-speed cryptosystems. In this paper, we survey existing works and concepts of finite automata cryptosystems with open key, its background and general algorithm of encrypting and decrypting process. According to the research carried out, it can be noted that in existing cryptosystems, finite automata of various types are used: finite automata of a general form, structural automata, finite automata with input-output memory of a special type, finite automata with pseudo-memory of a special type. The authors of the article were interested in the pseudo-memory automata that were used in FAPKC4. For a better understanding of the application of this type of finite automata in cryptography, the authors demonstrated an example of their application for encryption and decryption of information.