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Power Analysis has been studied since 1998 when P. Kocher et al. presented the first attack. From the initial Simple Power Analysis more complex techniques have been designed and studied during the previous decade such as Differential and Correlation Power Analysis. In this paper we revisit Simple Power Analysis which is at the heart of side channel techniques. We aim at showing its true efficiency when studied rigorously. Based on existing Chosen Message attacks we explain in this paper how particular message values can reveal the secret exponent manipulated during a modular exponentiation with a single power consumption curve. We detail the different ways to achieve this and then show that some blinded exponentiations can still be threatened by Simple Power Analysis depending on the implementation. Finally we will give advice on countermeasures to prevent such enhanced Simple Power Analysis techniques. [ABSTRACT FROM AUTHOR]

Fault attacks as introduced by Bellcore in 1996 are still a major threat toward cryptographic products supporting RSA signatures. Most often on embedded devices, the public exponent is unknown, turning resistance to fault attacks into an intricate problem. Over the past few years, several techniques for secure implementations have been published, all of which suffering from inadequacy with the constraints faced by embedded platforms. In this paper, we introduce a novel countermeasure mechanism against fault attacks in RSA signature generation. In the restricted context of security devices where execution time, memory consumption, personalization management and code size are strong constraints, our countermeasure is simply applicable with a low computational complexity. Our method extends to all cryptosystems based on modular exponentiation. [ABSTRACT FROM AUTHOR]

This paper proposes new chosen-message power-analysis attacks against public-key cryptosystems based on modular exponentiation, which use specific input pairs to generate collisions between squaring operations at different locations in the two power traces. Unlike previous attacks of this kind, the new attacks can be applied to all the standard implementations of the exponentiation process: binary (left-to-right and right-to-left), m-ary, and sliding window methods. The SPA countermeasure of inserting dummy multiplications can also be defeated (in some cases) by using the proposed attacks. The effectiveness of the attacks is demonstrated by actual experiments with hardware and software implementations of RSA on an FPGA and the PowerPC processor, respectively. In addition to the new collision generation methods, a high-accuracy waveform matching technique is introduced to detect the collisions even when the recorded signals are noisy and the clock has some jitter. [ABSTRACT FROM AUTHOR]

The doubling attack by Fouque and Valette and its analogue, the relative doubling attack, by Yen et al. are a new kind of simple power analysis that can be applied to a binary double-and-add algorithm in a scalar multiplication (or a multiply-and-square algorithm in a modular exponentiation). The doubling attack is very powerful because it requires just two queries to the device to find the secret key. The original doubling attack broke the binary double-and-add always algorithm and the relative doubling attack succeeded in breaking the Montgomery ladder. Fouque and Valette told that the doubling attack was applicable only to downward algorithms, i.e., ˵left-to-right″ implementations of a binary modular exponentiation and recommended to use upward ˵right-to-left″ implementations. On the contrary, Yen et al. proposed a new downward algorithm and asserted that it was secure against doubling attacks. This kind of controversy comes from the lack of analysis of the fundamentals of the doubling attacks. Therefore we analyze the characteristic of the doubling attack and propose a method to easily test a given algorithm΄s security against doubling attacks. Furthermore, we show Yen et al.΄s scheme is still vulnerable to the doubling attack. [ABSTRACT FROM AUTHOR]