Early-word-based montgomery modular multiplication algorithm

Modular multiplication is basic operation in public key cryptosystems like RSA. Montgomery modular multiplication being efficient is widely used. It is based on additions and shift operations. Each iteration requires a right shift, therefore in a word based architecture a complete word is not formed at end of iteration. This paper presents compute early word based scalable Montgomery architecture. It computes the most significant bit of word by applying 2 XOR operations. Also compute early scheme for common multiplicand Montgomery is proposed. Both the architectures are compared with previous architectures in literature.