Improve Security Algorithm Cryptography Vigenere Cipher Using Chaos Functions

This paper specifically discusses how chaos functions are applied in the crystallographic algorithm of vigenere cipher, along with the mechanism of chaos function to the vigenere cipher algorithm and the application of chaos theory to the level of ciphertext security which it will produce such as chaos theory that is logistic equation. In the world of cryptography, chaos theory is used to generate numbers at random. This random number will then be used as the key in performing the encryption process. The chaos function is a function that has a sensitive nature to the initial value, meaning that a small change in the initial value will result in a major change in the value of the next function. Such properties can be applied in cryptography to maintain data integrity, especially in stream cipher cryptographic algorithms such as vigenere cipher, vigenere cipher algorithms have problems with very low security levels. In the vigenere cipher algorithm a key, called the initial key, is made of a key longer than the initial key called a key stream that is very easy to solve. The application of chaotic function in vigenere cipher can improve the security of the key used, since the chaos function can generate random numbers for the initial key on the vigenere cipher algorithm that has the sensitive properties at the initial value.