Since the time public-key cryptography was introduced by Diffie and
Hellman in 1976, numerous public-key algorithms have been proposed. Some of these
algorithms are insecure and the others that seem secure, many are impractical, either
they have too large keys or the cipher text they produce is much longer than the
plaintext. This paper focuses on efficient implementation and analysis of two most
popular of these algorithms, RSA and ElGamal for key generation and the encryption
scheme (encryption/decryption operation). RSA relies on the difficulty of prime
factorization of a very large number, and the hardness of ElGamal algorithm is
essentially equivalent to the hardness of finding discrete logarithm modulo a large
prime. These two systems are compared to each other from different parameters points
of view such as performance, security, speed and applications. To have a good
comparison and also to have a good level of security correspond to users need the
systems implemented are designed flexibly in terms of the key size. پرونده مقاله