Exchange of data over the internet is increasing day-by-day. Security is the main issue in communication over a network. Protection must be given against intruders. Hence, cryptography plays a vital role in providing security. There are two basic types of cryptography: symmetric key and asymmetric key. Symmetric key uses same or single key for encryption and decryption whereas asymmetric key uses separate keys for encryption and decryption. The most commonly used are the symmetric key algorithms.