Implementation of a block cipher algorithm for medical information security on cloud environment: using modified advanced encryption standard approach

The need of keeping medical information safe and secure stems from the fact that doctors rely on it to make accurate diagnoses. If this information is altered in any way, no matter how minor, there is a risk of an inaccurate diagnosis, which could result in severe medical issues and death. The transition from paper to electronic health records (EHRs) has considerably improved patient care quality and efficiency. However, for many healthcare service providers, it has extended the attack surface. Because of the value of a patient's medical information, this has posed a threat to both patients and healthcare providers. When security is not taken into account in healthcare systems, patients' privacy is jeopardized. The intended solution to this challenge is to create a modified AES algorithm to secure patient medical information. Although, the AES algorithm is secure, however, there is always a need for improvement on any cryptographic algorithms in terms of computational cost. This study implements AES and modified the last round of the AES and their performance has been measured by scrambling input datasets of various contents and volumes. The experimental results show that modified AES outperforms AES algorithms in terms of Encryption time while AES outperform modified AES in terms of decryption time. Also, the Avalanche effect results revealed that modified AES has a higher avalanche effect for small-size files while a smaller avalanche effect for larger file sizes. This signifies that modified AES security is stronger for a small size file while conventional AES has higher security for larger file sizes. The average encryption time of the AES algorithm for text files is 1513.3ms while the modified AES average encryption time gives 1293.837ms. The average decryption time for conventional AES is 1289.627ms while the average decryption time for modified AES give 1400.136ms. Modified AES uses lesser time complexity during the encryption of all categories of data files while conventional AES uses lesser time complexity during the decryption of all categories of data files.