Cellular-array modular multiplier for fast RSA public-key cryptosystem based on modified booth's algorithm

Jin Hua Hong, Cheng Wen Wu

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)


We propose a radix-4 modular multiplication algorithm based on Montgomery's algorithm, and a fast radix-4 modular exponentiation algorithm for Rivest, Shamir, and Adleman (RSA) public-key cryptosystem. By modifying Booth's algorithm, a radix-4 cellular-array modular multiplier has been designed and simulated. The radix-4 modular multiplier can be used to implement the RSA cryptosystem. Due to reduced number of iterations and pipelining, our modular multiplier is four times faster than a direct radix-2 implementation of Montgomery's algorithm. The time to calculate a modular exponentiation is about n2 clock cycles, where n is the word length, and the clock cycle is roughly the delay time of a full adder. The utilization of the array multiplier is 100% when we interleave consecutive exponentiations. Locality, regularity, and modularity make the proposed architecture suitable for very large scale integration implementation. High-radix modular-array multipliers are also discussed, at both the bit level and digit level. Our analysis shows that, in terms of area-time product, the radix-4 modular multiplier is the best choice.

Original languageEnglish
Pages (from-to)474-484
Number of pages11
JournalIEEE Transactions on Very Large Scale Integration (VLSI) Systems
Issue number3
Publication statusPublished - 2003 Jun 1

All Science Journal Classification (ASJC) codes

  • Software
  • Hardware and Architecture
  • Electrical and Electronic Engineering


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