Software self-checking systems and methods
View Patent ↗Software self-checking mechanisms are described for improving software tamper resistance and/or reliability. Redundant tests are performed to detect modifications to a program while it is running. Modifications are recorded or reported. Embodiments of the software self-checking mechanisms can be implemented such that they are relatively stealthy and robust, and so that it they are compatible with copy-specific static watermarking and other tamper-resistance techniques.
1. A non-transitory computer-readable storage medium, the computer-readable storage medium storing programming instructions that, if executed by a processor of a computer system, are operable to cause the computer system to perform operations comprising:
calculating, by a self-checking code sequence included in a program, during execution of the program, a result of a function based on a portion of the program;
comparing, by the self-checking code sequence, the result with a predefined value;
determining, by the self-checking code sequence, that the result does not match a predefined value based on the comparison; and
triggering a tamper response mechanism based on the determination that the result does not match the predefined value.
2. The non-transitory computer-readable storage medium of claim 1 , wherein the self-checking code sequence comprises a first self-checking code sequence of a plurality of self-checking code sequences.
3. The non-transitory computer-readable storage medium of claim 2 , wherein the portion of the program comprises a first portion of a plurality of portions of the program.
4. The non-transitory computer-readable storage medium of claim 3 , wherein each portion of the plurality of portions comprises at least one corrector value.
5. The non-transitory computer-readable storage medium of claim 3 , wherein the plurality of portions of the program overlap at least in part.
6. The non-transitory computer-readable storage medium of claim 3 , wherein the self-checking code sequence is included in the first portion of the program.
7. The non-transitory computer-readable storage medium of claim 3 , wherein the self-checking code sequence is included in a second portion of the program different, at least in part, from the first portion.
8. The non-transitory computer-readable storage medium of claim 5 , wherein each self-checking code sequence of the plurality of self-checking code sequences is associated with a portion of the plurality of portions of the program in a relatively random fashion.
9. The non-transitory computer-readable storage medium of claim 3 , wherein the first self-checking code sequence is configured to check the integrity of at least one other self-checking code sequence of the plurality of self-checking code sequences.
10. The non-transitory computer-readable storage medium of claim 3 , wherein the plurality of self-checking code sequences are distributed in a relatively uniform fashion throughout the program.
11. The non-transitory computer-readable storage medium of claim 1 , wherein the function comprises a hash function.
12. The non-transitory computer-readable storage medium of claim 11 , wherein the hash function is invertible.
13. The non-transitory computer-readable storage medium of claim 11 , wherein the hash function is relatively lightweight.
14. The non-transitory computer-readable storage medium of claim 1 , wherein triggering the tamper response mechanism comprises terminating execution of the program.
15. The non-transitory computer-readable storage medium of claim 1 , wherein triggering the tamper response mechanism comprises disabling a function of the program.
16. The non-transitory computer-readable storage medium of claim 1 , wherein triggering the tamper response mechanism comprises terminating the ability of the program to access protected data.
17. The non-transitory computer-readable storage medium of claim 1 , wherein triggering the tamper response mechanism comprises generating and transmitting a message to a system administrator.