Hybrid cryptography technique using modified Diffie-Hellman and RSA

Abstract — Diffie-Hellman is public key based symmetric key algorithm used for secret key sharing between two parties over public communication channel. Diffie-Hellman is weak when there is man in middle attack done by eavesdropper. Diffie-Hellman algorithm is not provide authentication. Security of Diffie-Hellman cryptography system completely depends upon random prime number selected by user. Finding private key after accessing public key and prime number p is logarithmic problem to solve. Diffie-Hellman is modified to provide authentication and avoid primitive root generation step to achieve speed and authentication to avoid key exchange with unauthenticated user.RSA is cryptography system based on asymmetric key cryptography concept. Security of RSA is depend upon prime factorization of integer value n which globally known to everyone in system. In this paper hybrid cryptography system is proposed to achieve secret message exchange. RSA uses random prime numbers P and Q which after multiplication, value N is shared to other side of communication. Security of RSA is depend upon prime factorization of N. Newly proposed algorithm secretly generate value of N so that security level is increased in new RSA based cryptography system