an electronic data processing circuit includes an operating module such as a microprocessor , at least one data memory and a data bus extending between the data memory and the operating module . in order to provide an electronic data processing circuit which is better protected against undesired alterations , at least one encoding module is provided in the region between the data memory and the data bus and / or in the region between the operating module and the data bus . the encoding module is constructed in such a way that data traffic between the operating module and the data bus or between the data memory and the data bus can be encoded and / or decoded .