Introduction
Information security and a secure transmission of data
become very important in information and communication
technology. A third party can trap data or steal
important data stored in a computer. To prevent this, it
is advocated to encrypt the messages to provide information
security. This type of protection is usually provided
using cryptography. In cryptography, a key (K1) is used
to encrypt a message (called plaintext P) with encryption
algorithm (E) into ciphertext (C). The ciphertext is
converted into plaintext using a key (K2) and decryption
algorithm (D). There are two types of cryptography: