Given the haste with which cyber threats are emerging, the ability of universities to protect sensitive data is a challenging issue. The Advanced Encryption Standard (AES) is used very often because it is so efficient and robust to secure files. Nevertheless, growing method of attacks, for example, differential and brute force evaluations, order the improvement of the AES algorithm for raising security. In this paper, we propose to introduce a dynamic key expansion mechanism inside the AES, where the encryption parameters are adjusted depending on the application of real time access patterns and data sensitivity levels. We evaluate this modified AES variant based on the performance benchmarking and the simulated attacks against the compliance of the standard AES implementations, comparing the tradeoff between security strength, encryption speed, and computational overhead. The dynamic key expansion mechanism works on the basis of real time characteristics of access and data sensitivity and optimizes the encryption specification to prevent both brute force and differential attacks without degrading the performance factor such as confidentiality, integrity, availability, speed and computation overhead. Results show that dynamic key expansion is an effective means of mitigating certain attack vectors without sacrificing speed in encryption, and hence is a solution that can fairly secure the files at a university without egregious resource demand.

Keywords: Advanced Encryption Standard (AES), dynamic key expansion, file security, university networks, cryptographic attacks