Method and arrangement for preventing unauthorized execution of computer programs and a corresponding software product and a corresponding computer-legible storage medium

摘要

The invention describes a method and an arrangement for preventing unauthorized execution of computer programs and a corresponding software product and a corresponding computer-legible storage medium which can be used in particular to secure self-tests based on the test ROM in Smartcards against unauthorized execution of these tests. The evaluation of the test procedure takes place by means of a signature register which records all code and data transfers and encrypts these together. The execution of the test ROM is generally regarded as highly security-relevant and is subject to various protective measures e.g. fuses. The invention extends these protective measures in that, on execution of the test ROM, new signatures are generated in the register. During the program execution of the test ROM, the content (or an individual bit) of the signature register is compared with a signal supplied via an I/O pad. If the bit from the signature register and the externally entered signal differ, a reset is triggered. Execution of the test ROM is therefore possible only if the internally generated signature is known. Security-relevant processes in the test ROM execution can thus be effectively protected.