| 摘要 |
A software controlled device comprises a central processing unit (CPU) 2 and a memory unit 3. The CPU comprises a digital signature algorithm 6 and a private key 5; wherein the memory unit stores run-time binary code. A digital signature 4 is derived during manufacture from the digital signature algorithm, the private key and the run time binary code, then stored in the CPU and, in use, the CPU recalculates the digital signature and compares it with the stored digital signature, such that if the two signatures are not identical, the run-time code will not execute. A method of preventing fraudulent use of an electronic device comprising a central processing unit (CPU) and a memory unit is also provided. The method comprises passing run-time binary code and a private key through a digital signature algorithm during manufacture to derive a digital signature; storing the derived digital signature in the CPU; and in use, recalculating the digital signature and comparing it with the stored digital signature, such that if the two signatures are not identical, the run-time code will not execute. A JTAG part may be provided for programming the private key. The private key may be at least a 128 bit key.
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