Analysis of Ciphertext Behaviour Using the Example of the AES Block Cipher in ECB, CBC, OFB and CFB Modes of Operation, Using Multiple Encryption

• Published in: Intelligent Information and Database Systems Vol. 13758; pp. 621 - 629
• Main Authors: Alimzhanova, Zhanna, Nazarbayev, Dauren, Ayashova, Aizada, Kaliyeva, Aktoty
• Format: Book Chapter
• Language: English
• Published: Switzerland Springer 2022; Springer Nature Switzerland
• Series: Lecture Notes in Computer Science
• Subjects: AES; Block cipher; CBC; CFB; Ciphertext; ECB; Mode of operation; Multiple encryption; OFB; Periodicity
• ISBN: 9783031219665; 303121966X
• ISSN: 0302-9743; 1611-3349
• DOI: 10.1007/978-3-031-21967-2_50

This paper explores the Advance Encryption Standard (AES) block cipher in Electronic Code Book (ECB), Cipher Block Chaining (CBC), Output Feedback (OFB) and Cipher Feedback (CFB) modes of operation to compare the characteristic properties of ciphertext, and to compare the block complexity level of building ciphertext schemes using the methodology of periodic regularities. This paper investigates the features of four block modes of operation, which includes two analytical principles: the first principle, which defines periodicity with respect to the ciphertext; and the second, which includes the principle of repeated cipher iterations, to react the characteristic manifestations of the ciphertext, under certain control input data. In accordance with the above principles, the results of analysis of the regularities of ciphertext with respect to blocks and with respect to encryption iterations were shown in tables and respectively in obtained formulae. The package Matplotlib of the Python programming language was used for graphical visualization ciphertexts of first iteration of encryption on all investigated modes of operation under different key sizes. The implementation of AES algorithm and obtaining encryption results were performed using the package Crypto.