Design and implement a reverse key algorithm for the AES 128 bit cryptography

• Main Author: Cheng, Vjin
• Other Authors: Gwee Bah Hwee
• Format: Final Year Project
• Language: English
• Published: 2015
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: http://hdl.handle.net/10356/64545
• Institution: Nanyang Technological University

In today’s digital era, all kinds of information and data are being shared and transmitted across networks and systems. These data may sometimes be sensitive and needed to be secured, only accessible to selected viewer. With that the need for encryption on data is created, providing a layer of protection towards data. Advance Encryption Standard 128 bit (AES 128) is among the most popular secret key technique encryption being used today. The secret key value is the heart of AES encryption and must always remain hidden to ensure the encryption is secured. Since valuable information is present within encrypted data, cryptanalysis which is the study of ciphers with the aim of breaking the encryption is born. Side channel attack is a type of cryptanalysis which focuses on the weakness within the physical implementation of cryptosystem. Power analysis attack is a branch of side channel attacks and uses the leaked voltages to form a pattern and link to the secret key values. In this project, the student is tasked with creating a tool that helps in the process of power analysis attack on AES encryption system. This tool will help in finding the secret key values based on partial information on the secret key gathered by the attack. The tool consists of an algorithm that will reverse engineer certain valid steps used for AES encryption to generate the secret key. This algorithm was given the name “Reverse Key Algorithm”. Besides formulating the algorithm theoretically, the student task was also task to implement and test this algorithm in both software program (MATLAB) and digital hardware circuit design (Multisim). The implementation of both methods was found to be a success, as the original key was successfully found after performing sample tests. The results also showed that hardware implementation was found to be approximately 50% quicker than the software. Based on the results, it was proven that the reverse key algorithm formula was indeed accurate and can be used as a tool for cryptanalysis attack on Advance Encryption Standard in finding the original key values.