Block Cipher Modes

Block cipher is one of the most widely-used tool in cryptography, and its mode of operation features the use of a symmetric-key block-cipher algorithm in providing information security such as confidentiality or authenticity. Five modes of operation with AES algorithm will be discussed in this paper: Electronic Codebook (ECB), Cipher Block Chaining (CBC), Cipher Feedback (CFB), Output Feedback (OFB), and Counter (CTR). These modes can provide cryptographic protection for sensitive, but classified, computer data.

Keywords: Computer security; cryptography; block cipher; mode of operation

Block cipher is one of the most widely-used tool in cryptography, but itself is only used of one fixed-length group of bits called a block [1]. A mode of operation describes how to repeatedly apply a cipher's single-block operation to securely transform amounts of data larger than a block [2].

The five modes—the Electronic Codebook (ECB), Cipher Block Chaining (CBC), Cipher Feedback (CFB), Output Feedback (OFB), and Counter (CTR) modes can provide data confidentiality.

[1] Plass, Jan L., Roxana Moreno, and Roland Brünken. Cognitive Load Theory. Cambridge University Press, 2010.

[2] Mayer, Richard E. The Cambridge handbook of multimedia learning. Cambridge University Press, 2005.

[3] Kirschner, P. A, Sweller, J. and Clark, R. E. Why minimal guidance during instruction does not work: An analysis of the failure of constructivist, discovery, problem-based, experiential, and inquiry-based teaching. Educational psychologist 41, no. 2, pp 75-86, 2006