2014 32nd IEEE International Conference on Computer Design (ICCD) (2014)
Seoul, South Korea
Oct. 19, 2014 to Oct. 22, 2014
Darshana Jayasinghe , School of Computer Science and Engineering, University of New South Wales, Australia
Roshan Ragel , Department of Computer Engineering, University of Peradeniya, Sri Lanka
Jude Angelo Ambrose , School of Computer Science and Engineering, University of New South Wales, Australia
Aleksandar Ignjatovic , School of Computer Science and Engineering, University of New South Wales, Australia
Sri Parameswaran , School of Computer Science and Engineering, University of New South Wales, Australia
Advanced Encryption Standard (AES) is arguably the most popular symmetric block cipher algorithm. The commonly used mode of operation in AES is the Electronic Codebook (ECB) mode. In the past, side channel attacks (including power analysis based attacks) have been shown to be effective in breaking the secret keys used with AES, while AES is operating in the ECB mode. AES defines a number of advanced modes (namely Cipher Block Chaining - CBC, Cipher Feedback - CFB, Output Feedback - OFB, and Counter - CTR) of operations that are built on top of the EBC mode to enhance security via disassociating the encryption function from the plaintext or the secret key used. In this paper, we investigate the vulnerabilities against power analysis based side channel attacks of all such modes of operations, implemented on hardware circuits for low power and high speed embedded systems. Through such an investigation, we show that AES is vulnerable in all modes of operations against Correlation Power Analysis (CPA) attack, one of the strongest power analysis based side channel attacks. We also quantify the level of difficulty in breaking AES in different modes by calculating the number of power traces needed to arrive at the complete secret key. We conclude that the Counter mode of operation provides a balance in between area and power while maintaining adequate resistance for power analysis attacks than when used with other modes of operations. We show that the previous recommendations for the rate of change in the keys and vectors is grossly inadequate, and suggest that it must be changed at least every 210 encryptions in CBC mode and 212 encryptions in CFB, OFB and CTR modes in order to resist power analysis attacks.
Encryption, Mathematical model, Correlation, Equations, Registers, Power demand
D. Jayasinghe, R. Ragel, J. A. Ambrose, A. Ignjatovic and S. Parameswaran, "Advanced modes in AES: Are they safe from power analysis based side channel attacks?," 2014 32nd IEEE International Conference on Computer Design (ICCD), Seoul, South Korea, 2014, pp. 173-180.