Cryptographic devices can be subject to side-channel attacks. Among those attacks, Differential Power Analysis (DPA) has proven to be very effective and easy to perform. Several countermeasures have been proposed in the literature. However, the effectiveness of these counter measures is still evaluated by resort-ing to intensive DPA simulations and constitutes a very time-consuming design task. In this paper we show that the knowledge of the structure of the circuit can be exploited to improve performances of the DPA. We propose to realign power consumption traces according timing information (i.e., path delays). We show the usefulness of the proposed method by comparing the efficiency of classic DPA w.r.t. timing aware DPA.

In the field of the Side Channel Analysis (SCA), the electromagnetic radiation of a cryptographic device is the richest source of information. Indeed, it permits to be more accurate by positioning smartly the EM probe near a given logic, filtering the signal that is not useful regarding a given attack. But this advantage can become easily a drawback if the attacker is unable to position her probe onto the device. Our contribution consists in giving an accurate method detecting an hot spot onto the device, i.e. the position where a correlation electromagnetic attack (CEMA) should be the most successful. This strategy is based on an indicator evaluated during a cartography. Its performance has been tested on an hardware AES implemented on an Altera Stratix II.

In the field of the side channel analysis, hardware distortions such as glitches and random frequency are classical countermeasures. A glitch influences the side channel amplitude while a random frequency damages the signal both in time and in amplitude. For minimizing these countermeasures effects, some trace treatments based on peak extraction or auto-correlation methods exist. However, none of them takes into account the amplitude mistake. In this paper, we show that this amplitude mistake is created by glitches but also by a random frequency. We propose then a reshaping processing that erases these effects on side channel traces both on the time and amplitude axis. The solution reconstructed a side channel signal, avoiding the hardware countermeasures and the clock relativity consequences which can be meaningful for Side Channel Attacks. Its efficiency is demonstrated on a Differential Power Attack performed on a DES implementation and on a Template Attack performed on a RSA implementation.

In this paper, we present a new fault attack on elliptic curve scalar product algorithms. This attack is tailored to work on the classical Montgomery ladder method when the $y$-coordinate is not used. No weakness has been reported so far on such implementations, which are very efficient and were promoted by several authors. But taking into account the twist of the elliptic curves, we show how, with few faults (around one or two faults), we can retrieve the full secret exponent even if classical countermeasures are employed to prevent fault attacks. It turns out that this attack has not been anticipated as the security of the elliptic curve parameters in most standards can be strongly reduced. Especially, the attack is meaningful on some NIST or SECG parameters.