MATLAB-BASED SOFTWARE TOOL FOR IMPLEMENTATION OF TRIFID CIPHERS USING 64-SYMBOL ALPHABET
MATLAB-BASED SOFTWARE TOOL FOR IMPLEMENTATION OF TRIFID CIPHERS USING 64-SYMBOL ALPHABET

Summary/Abstract: The development of information and communication technologies is the dominant factor for the sustainable development of society. Problems of information security are of fundamental importance for the society. To achieve the required levels of security of the information a highly qualified personnel is needed. In this regard increased attention is paid to the training of specialists in this field, based on the continuous improvement of the educational process. The paper presents one of the classical ciphers in cryptography, the trifid cipher, a type of cipher that was used historically but now has fallen into disuse. Most classical ciphers can be practically computed and solved by hand. They are also usually very simple to break with modern technologies. In classical cryptography, the trifid cipher extends the concept of the bifid cipher to a third dimension, allowing each symbol to be fractionated into three elements instead of two. The trifid cipher turns them into coordinates on a 3×3×3 cube. As with the bifid cipher, this is then combined with transposition to achieve a higher degree of diffusion because each output symbol depends on three input symbols instead of two. Thus the trifid cipher was the first practical trigraphic substitution. The paper describes a modified algorithm for implementing the trifid cipher where 64-symbol alphabet (Latin letters, decimal digits and punctuation signs) is used and each symbol is fractionated into three elements turned into coordinates on a 4×4×4 cube. The paper presents MATLAB-based software tool implementing encryption and decryption of English texts using the trifid cipher and 64-symbol alphabet. The tool will be used in the course “Telecommunication Security” by students of the specialty “Telecommunication Systems” for the Bachelor degree at the University of Ruse.

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