CARRY SAVE COMMON MULTIPLICAND MONTGOMERY FOR RSA CRYPTOSYSTEM

RSA public key cryptosystem provides encryption and digital signatures. With growth of key size an efficient design of RSA in terms of area, frequency, throughput and power consumption is hard to achieve. Also with the different type of attacks possible, a need for secure RSA cryptosystem which is attack resistant has arisen. This study presents RSA design with Montgomery powering ladder and proposed carry save common multiplicand Montgomery on FPGAs. Since the modular exponentiation is based on Montgomery powering ladder therefore it is power attack resistant. Common multiplicand Montgomery modular multiplication reduces the complexity by computing once the common operations in modular squaring and modular multiplication. The proposed carry save common multiplicand Montgomery modular multiplication maintains intermediate results in carry save form and utilizes the DSP slices to convert the redundant results into binary at the end of the modular multiplication. The proposed RSA design implemented on FPGAs is efficient in terms of area, frequency, power consumption and is power attack resistant.