Novel Technique to Enhance Security of Reconfigurable Circuits

FPGAs are used in various applications like aero-space, automotive, military etc which require them to operate in different types of environments. Security of FPGA based system is a big concern as the system developed after lot of research can be stolen very easily. Nowadays, a lot of research is going on, considering various security aspects of FPGAs as the primary concern. Several cryptographic systems are available which can be used to protect FPGA bit-streams. Cryptographic techniques are used to encrypt the FPGA bit-streams. It is not feasible to use FPGAs in small circuit as it increase cost of the system under consideration. This paper proposes a technique which makes a digital system secure by using look-up tables. Behavior of a look-up table is based on its configuration bit. Look-up tables can be used to replace a digital circuit either fully or partially. If a look-up table replaces the whole circuit, then it can be called as fully incomplete and if the look-up table replaces only a part of a digital circuit, then that circuit can be called as partially incomplete. Digital systems can be made secure by fully incomplete design or partially incomplete design. Fully incomplete design can be used in the case of small circuits and for complex circuits a portion of the design can be made incomplete, in the case of partially incomplete digital circuits. This paper proposes a novel technique to enhance security of reconfigurable circuit. An authorized user completes the design of the circuit at run time by entering the configuration bits of the look-up table.