Highlighted with the newly released intellectual property (IP) protection white paper by VSI Alliance, the protection of virtual components (VCs) has received a large amount of attention recently. Digital signature is one of the most promising solutions among the known protection mechanisms. However, the trade-off between hard-to-attack and easy-to-detect and the lack of efficient detection schemes are the major obstacles for digital signatures to thrive. In this paper, we propose a new watermarking method which (i) allows the watermark to be public detected without forensic experts, (ii) gives little advantage to attackers for forgery, and (iii) does not lose the strength of protection provided by other watermarking techniques. The basic idea is to make part of the watermark public. We explain the concept of this public-private watermark and discuss the generation and embedding of such marks. We use popular VLSI CAD problems, namely technology mapping, partitioning, graph coloring, FPGA design, and Boolean satisfiability, to demonstrate its easy detectability, high credibility, low design overhead, and robustness. Finally, this technique is compatible with all the known watermarking and fingerprinting techniques.