An improved Montgomery´s algorithm for high-speed RSA public-key cryptosystem

We revise Montgomery´s algorithm such that modular multiplication can be executed two times faster. Each iteration in our algorithm requires only one addition, while that in Montgomery´s requires two additions. We then propose a cellular array to implement modular exponentiation for the Rivest-Shamir-Adleman cryptosystem. It has approximately 2n cells, where n is the word length. The cell contains one full-adder and some controlling logic. The time to calculate a modular exponentiation is about 2n/sup 2/ clock cycles. The proposed architecture has a data rate of 100 kb/s for 512-b words and a 100 MHz clock.