Publications
Security enhancement of AES-CBC and its performance evaluation using the avalanche effect
Dec 21, 2021Journal 2020 3rd International Conference on Engineering Technology and its Applications, IICETA 2020
Publisher IEEE
DOI 10.1109/IICETA50496.2020.9318803
The security of communication systems is becoming a significant concern with the increase in computational power. High-security cryptographic algorithms are required to protect the privacy of information from unauthorized access. This paper presents a security enhancement of Advanced Encryption Standard (AES) in Cipher Block Chaining (CBC) mode and its performance evaluation using the Avalanche Effect. In this study, a new improved technique for increasing the security of the AES-CBC is introduced. The Unix time is used as a source for Initialization Vector (IV) in CBC mode before encryption rounds. The results showed that the algorithm generates different ciphertext at each execution. In other words, different ciphertext output significantly decreases the risk of cracking the encryption key. Moreover, the results are examined using the Avalanche Effect and tested for satisfying the security criteria. The achieved results showed that the encryption method succeeds in maintaining the avalanche effect requirement and introducing additional strength to the encryption process by preventing the encryption key update for every new ciphertext.
Generation and Evaluation of a New Time-Dependent Dynamic S-Box Algorithm for AES Block Cipher Cryptosystems
Dec 9, 2020Journal IOP Conference Series: Materials Science and Engineering
Publisher IOP
DOI 10.1088/1757-899X/978/1/012042
Cryptographic communication systems depend extensively on the Advanced Encryption Standard (AES) block cipher algorithm. The encryption strength in the AES algorithm is derived from the nonlinearity introduced by the application of s-boxes inside the encryption process. Today, most s-boxes are either static in which the s-box content does not change during the encryption process or dynamic which continuously changes depending on the encryption key. Two major problems exist in such systems that increase the risk of unauthorized decryption. First, the encryption of the same data yields the same cipher key repeatedly. Seconds, the key-dependent s-boxes require sharing the encryption key each time a new s-box is generated. In this paper, a dynamic s-box is introduced that constantly changes independent of the encryption key. The new s-box depends on the epoch timestamp that exists in every digital system as well as transmitted with digital satellite communication systems. The generation of the nonlinear s-box occurs inside the transmitter and receiver identically. The main strength of the proposed approach is that the ciphertext changes while keeping the encryption key constant ensuring different encryption results for the same data. This paper also investigates and analyzes the strength and quality of the new s-box using the avalanche effect method. The results showed that different ciphertext is produced after every encryption process. Moreover, the modified dynamic s-box reached a high avalanche effect exceeding the Strict Avalanche Criterion (SAC).