Soft IP Protection: Watermarking HDL Codes

Intellectual property (IP) reuse based design is one of the most promising techniques to close the so-called design productivity gap. To facilitate better IP reuse, it is desirable to have IPs exchanged in the soft form such as hardware description language (HDL) source codes. However, soft IPs have higher protection requirements than hard IPs and most existing IP protection techniques are not applicable to soft IPs. In this paper, we describe the basic requirements, make the necessary assumptions, and propose several practical schemes for HDL code protection. We protect the HDL codes by hiding author’s signature also called as watermarking, similar to the idea for hard IP and multimedia data protection. But the new challenge is how to embed watermark into HDL source codes, which must be properly documented and synthesizable for reuse. We leverage the unique feature of Verilog HDL design to develop several watermarking techniques. These techniques can protect both new and existing Verilog designs. We watermark SCU-RTL & ISCAS benchmark Verilog circuits, as well as a MP3 decoder. Both original and watermarked designs are implemented on ASICs & FPGAs. The results show that the proposed techniques survive the commercial synthesis tools and cause little design overhead in terms of area/resources, delay and power.