A Complex Transformation of Monoalphabetic Cipher to Polyalphabetic Cipher: (Vigenère-Affine Cipher)

Abstract

Fast progression of digital data exchange in electronic way, information security is becoming much more important in data storage and transmission on public communication networks. Cryptography has come up as a solution which plays a vital role in information security system against malicious attacks. In cryptography, there are various cipher techniques such as monoalphabetic cipher, polyalphabetic cipher, etc. to support data confidentiality as security mechanisms. They are methods of encrypting plain text message into cipher text protecting it from adversaries. The process of encryption of alphabets is the converting original message into non readable form. One of the most popular cipher techniques is the Vigenè re cipher. It is a polyalphabetic cipher technique which uses the Vigenè re table for the process of encryption of alphabets. As the Vigenè re cipher does not have the properties of diffusion and confusion, it is longer vulnerable to Kasiski and Friedman attacks based on letter frequency analysis. Thus, in this paper we propose a polyalphabetic cipher that is a new encryption and decryption technique with diffusion and confusion properties based on the concept of the complex cipher used by combining of Vigenè re cipher with Affine cipher for the increase of data security in data storage and transmission on public communication networks. Our proposed technique can also be considered as a complex transformation technique from Affine cipher known as a monoalphabetic cipher technique to a new polyalphabetic cipher technique that is called Vigenè re-Affine cipher.

Outer-Convex Dominating Set in the Corona of Graphs as Encryption Key Generator

“…In [18], they propose a polyalphabetic cipher with diffusion and confusion properties based on the concept of the complex cipher used by combining of Vigenére cipher with Affine cipher. Yamuna et al [19] presented an encryption mechanism using Hamilton path properties (path that covers all vertices in the graph).…”

Designing a New Hybrid Cryptographic Model

“…In addition to monoalphabetic and polyalphabetic methods, the methods obtained by combining these two different methods are used for encryption. Vigenère cipher with Affine cipher method is a new method that the polyalphabetic Vigenère method and monoalphabetic Affine method have been combined to provide for better results [1]. Similarly, Vigenère and Caesar cipher methods have been used together for more secure encryption [18].…”

Modified Vegenere Cipher to Enhance Data Security Using Monoalphabetic Cipher

“…Suppose the key is used along m then k1, k2, k3, …., km, plain text is the sequence of alphabets p1, p2, p3, ….,pm, and ciphertext is sequence of c1, c2,…., cm. Key, plaintext, and ciphertext are satisfied by equation below [6]:…”

“…P = ((C -k2) x k1 -1 ) mod n (5) P = ((C -k2) x k1 -1 ) mod 26 (6) In the decryption process there is a modular multiplicative inverse of k1 -1 mod 26 in Figure 2. Modular multiplicative inverse can be formulated as: 1≡ k1.k1 - (10) Equation (7) can be fulfilled if k1 and n are coprime [6].…”