One of the greatest breakthrough in the field of cryptography is the invention of public key cryptosystem, a highly secure scheme for message confidentiality and authentication. Among all the pOne of the greatest breakthrough in the field of cryptography is the invention of public key cryptosystem, a highly secure scheme for message confidentiality and authentication. Among all the public key cryptosystems, Rivest Shamir Adleman (RSA) cryptosystem seems to be the most commonly used. This work therefore presents an improved Rivest Shamir Adleman (RSA) key generation algorithm for security enhancement against modules attack. The improved algorithm makes use of four large primes p, q, r and t which increases the complexity of the algorithm as compared to conventional RSA algorithm which is based on only two large primes p and q (RSA2). In the improved RSA key generation algorithm using four primes (RSA4), encryption and decryption process is based on module n, a product of two large primes (n=p*q) but the values of private key (D) and public key (E) are based on the product of four large prime numbers (N=m*n) making the system highly secured.
