A method for preventing the unauthorized modification of a software or unauthorized modification of runtime data. According to this method, a converter, which is capable of converting the software into a generalized machine code is provided. The converter is designed such that it cannot be reverse engineered, by using a conversion process that causes data loss. An interpreter, which the knowledge of its process method is kept restricted, is also provided. The interpreter interprets the general machine code into a specific machine code, while reconstructing the lost data during the interpretation process.