Feistel-Based Cryptographic Algorithm

Overview

This project implements a Feistel-based encryption algorithm, similar to DES, incorporating some novel ideas from the paper "An innovative method for enhancing the AES algorithm based on a magic square of order 6". The encryption process includes an initial permutation, a Feistel network, and a final inverse permutation to secure data.

Algorithm Structure

1. Initial Permutation (IP):

   • A permutation is applied to the input block using a table similar to the initial DES permutation.

2. Feistel Network:

   • The main encryption is done using a Feistel network, with multiple rounds of XOR, S-box substitution, and a magic square transformation for added complexity and reduced execution time.
   • The right half of the block is transformed and combined with the left half through XOR. After each round, the left and right halves are swapped.
   • This process repeats for 16 rounds, ensuring that the entire data block is thoroughly mixed and dependent on the key.

3. Magic Square:

   • The algorithm introduces a magic square transformation to replace the MixColumn function in AES, enhancing encryption security and reducing computation time.
   • A 6x6 magic square is used for nonlinear transformations, further obfuscating the relationship between the plaintext and ciphertext.

4. Final Permutation (IP-1):

   • After the Feistel rounds, a final permutation similar to DES is applied to the output.

Key Generation

• A 64-bit key is used, and subkeys are generated using Linear Feedback Shift Registers (LFSR). The subkeys are used in each round of the Feistel network.

Features

Architecture

Code Implementation

The algorithm's Python implementation can be found in the file NegarFeistelCipher.py in the repository. It includes:

• Functions for the initial and final permutation.
• Key generation using LFSR.
• Feistel round processing, including XOR and S-box transformations.
• Magic square processing for nonlinear encryption steps.

Performance

The proposed algorithm increases security by making linear and differential cryptanalysis more difficult while reducing execution time compared to traditional AES.

This algorithm is particularly efficient for image encryption, providing high security while maintaining low execution time.

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