A tamper-proof software watermark using code encryption

Utilizing a modified PPCT structure, a tamper-proof software watermark solution with code-based encryption is proposed. The General Chinese Remainder Theorem is exploited to split the watermark which is represented as a big number into pieces to enhance stealth. Changes to the source and object code are made to embed the watermark, and according to certain policies some parts of object code are encrypted with an en/decryption key which is highly coupled with object code to increase robustness and tamper-proof capability.