An IP Protection Algorithm by Watermarking Multiple Scan Chains Based on Minimum Correlation Degree of Vectors

With the rapid development of deep sub-micron integrated circuit systems, existing Intellectual Property (IP) watermarking methods for scan chains are mainly implemented by reordering and reconstructing scan chain for protecting reused IP cores. These methods may cause high vector correlation of IP watermark, which will seriously affect overhead and reliability. A multiple scan chains-based IP protection method with minimum test vectors was proposed in this paper. Firstly, the test vector sequence for scan input was generated by the generator of pseudo-random test vector, then the multiple scan chains-based watermarking structure with minimum correlation degree of vectors were constructed by combining the generated sequence with the circuit-under-test. By adding constraints in the structure, watermark would be restricted to positions of certain scan cells. Finally, the watermark was inserted and extracted by altering states of specific registers in scan cells with the designed logic circuit for bit alteration. With no influence on normal circuit function, the proposed algorithm could embed and extract the information of the user´s legitimate ownership and effectively address high power overhead and low security. The experiments were conducted on ISCAS-89 benchmarks. The results showed that the resource overhead in watermark embedding was reduced by more than 8% under the condition of adding constraints.