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Iti Scotland Limited

Graeme Harkness

Neil William Stewart

Anti-tamper techniques for protecting a program code portion against tampering provide for defining a sequence of code segments having a root-code segment and a plurality of sub-code segment. Each sub-code segment is provided with an integrity checking portion for checking the integrity of a target code segment. At runtime, the integrity checking portion of a given sub-code segment carries out a checking procedure on the respective target code segment to obtain a runtime result which is compared with a reference result to verify that the target portion of the program has not been tampered with.

Anti-tamper techniques

In order to protect a software program, at least one corruption function is included in the program. Also included in the program is at least one instruction that causes the program to be directed to the corruption function. An available breakpoint is then set such that, when the starting location of the corruption function is reached, an exception is generated and the handling of the exception causes the corruption function not to run. This has the effect that, if a malicious user attempts to use the available hardware breakpoint to perform unauthorized actions on the software program, the corruption function will run, and the software program will be unusable.

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Glasgow, United Kingdom

Graeme Harkness