Slovak University of Technology in Bratislava
Faculty of electrical engineering and information technology
Degree Course: INFORMATICS
Author: Ladislav Medveczky
Thesis: Electronic cash
Supervisor: Doc. RNDr. Otokar Grošek CSc.
December 1997

The aim of this project is to design and implement a simulation version of an electronic payment system, based on digital coins. The current version runs on a single workstation.

The system enables to simulate all operations, which have to be performed when purchasing electronic goods (data, software, etc.) through a computer network, from the user’s terminal. It allows to demonstrate the withdraw procedure, how to complete a purchase, the payment for the received goods and finally the deposit procedure of the coins back to the bank account of the user.

All these operations performed by the system can be comfortable controlled by means of user-friendly user interface.

The electronic coins are saved on the user’s disk, in a database, which serves as an electronic wallet. The user has a possibility to browse its contents, too. The database containing ”security sensitive” data as electronic stocks and encryption keys is ciphered to protect the data against an unauthorized access.

The security of the communication among the participants of the system is guaranteed by an asymmetric cryptosystem (RSA). Moreover the system requires a symmetric algorithm IDEA and an one-way message digest algorithm MD5, which can be simply substituted by other algorithms (e.g. DES and SHA), if necessary.

The development of the system was realized in the VisualWorks v2.5 enhanced by the object-technology of ArtInAppleS Ltd. As the cryptographic support, the RSAEuro Cryptographic Toolkit (written in C) was exploited.

The system is platform independent and it can be ported to other operation systems (Windows NT, OS/2 , UNIX) without recompilation or any change in the source code.