An FSM-based IP protection technique using added watermarked states

Nowadays, IP watermarking becomes the state-of-the-art technique in the field of IP protection. This technique aims at implanting a message such as a signature into the structure without changing the original functionality. One of the mainstreams of IP watermarking research is the Finite State Machines (FSM) watermarking. In this paper, we propose two FSM watermarking techniques which embed a signature of the IP creators in the state-transition-graph (STG) by adding new states, so-called watermarked states (WS). They are Front-added Watermarked States (FAWS) and Back-added Watermarked States (BAWS). Two FSM cores, i.e. simple CPU and UART transmission, are built and watermarked successfully in order to verify the effectiveness of the proposed techniques. Experimental results show that the FAWS method has the average cell and area overhead is 14.25% and 6.47%, respectively. Likewise, the increasing of cell and area of the BAWS method is 15.63% and 8.16%, respectively.