MS Excel-based Implementation of Schmidt-Samoa Cryptosystems

This paper describes the working principle of a Schmidt-Samoa cryptosystem, examining in detail the three main stages – key generation, encryption, and decryption. The most difficult points in the three stages are pointed out, with guidance given for dealing with the elusive problems – for example, determining the modular multiplicative inverse of an integer, as well as doing exponentiation when using large numbers, applying the "Square and Multiply" approach. An MS Excel implementation of the Schmidt-Samoa cryptosystem is described, which allows a very visual tabular representation of the three stages. Each of the three modules is explained in detail through a specific example. Numerous examples of encryption and decryption with the developed application are given, which find application in the educational process of the course "Telecommunication Security" for bachelor students of the "Internet and Mobile Communications" specialty at the University of Ruse.