1024-Bit/2048-Bit RSA Implementation on 32-Bit Processor for Public Key Cryptography

Abstract

In e-commerce, public key cryptography is used for signing, authentication, encryption and key exchange. Among all public key schemes, RSA has become very attractive due to its popularity and expiry of patent. Availability of high speed RSA algorithm will further give the impetus for the growth of e-commerce. This paper shows the implementation of RSA using 16-bit and 32-bit words for key lengths of 1024-bit and 2048-bit. The RSA key lengths of 1024-bit and 2048-bit are handled using multi-precision integer (MPI) of base 2³². In conventional RSA, the RSA exponent is processed bitwise and leads to slower implementation. Instead, if two bits are processed at a time using some precomputation technique, it is possible to improve the speed of RSA. In 32-bit implementation, two such bits of RSA exponent are processed for improving the speed and results are presented.