Kriptografi Polyalphabetic

Abstract

Abstrak. Kriptografi polyalphabetic merupakan improvisasi dari teknik substitusi monoalphabetic. Polyalphabetic substitution chiper melakukan teknik kriptografi monoalphabetic satu kali proses untuk suatu plainteks pesan. Algoritma polyalphabetic cipher membuat ciperteks lebih kuat untuk dapat dipecahkan karena karakter plainteks yang sama tidak dienkripsi dengan cipherteks yang sama. Kunci enkripsi polyalphabetic cipher dapat berbeda sehingga mempunyai kemungkinan kombinasi yang lebih bervariasi dan lebih sulit dipecahkan. Metode Vigenere cipher menjadi dasar dari polyalphabetic substitution cipher. Teknik enkripsi Vigenere cipher menggunakan tabel yang dikenal dengan tabel Vigenere yang digunakan dan menjadi acuan dibeberapa algoritma pengembangan metode polyalphabetic cipher. Metode polyalphabetic cipher lain adalah playfair cipher, menggunakan tabel kunci berupa matriks 5x5 untuk proses enkripsi sehingga memiliki 25! kemungkinan kunci yang cukup sulit dipecahkan.

Kata kunci : polyalphabetic cipher, vigenre cipher, playfair cipher

Abstract. (Polyalphabetic Cryptography) Polyalphabetic cryptography is an improvisation of monoalphabetic substitution techniques. Polyalphabetic substitution cipher performs one-time monoalphabetic cryptographic technique for a message text message. The polyalphabetic cipher algorithm makes cipertext stronger to be solved because the same plaintext character is not encrypted with the same ciphertext. The key to polyalphabetic cipher encryption can be different so that it has a more varied and more difficult to solve combination possibilities. The Vigenere cipher method is the basis of polyalphabetic substitution cipher. Vigenere cipher encryption techniques use tables known as Vigenere tables which are used and become references in several algorithms for developing polyalphabetic cipher methods. Another polyalphabetic cipher method is playfair cipher, using a key table in the form of a 5x5 matrix for the encryption process so that it has 25! Possible keys that are quite difficult to solve.

Keywords: polyalphabetic cipher, vigenere cipher, playfair cipher