Watermarking-based copyright protection of sequential functions

Watermarking is one of several techniques available today to deter copyright infringement in electronic systems. The technique consists of implanting indelible stamps in the circuit's inner structure, while not disrupting its functionality nor degrading its performance significantly. In this paper, a novel method is proposed for the creation of watermarks in regular sequential functions. This is an important class of functions, as it is the basis of most digital controllers. Algorithms are proposed for implanting robust watermarks to minimize the overhead and, ultimately, to reduce the impact on performance. Detection methods have been discussed in the presence of infringement attacks. The resilience of the method in several tampering regimes has been estimated. Examples illustrate the suitability of the approach.