Diffusional Side-Channel Leakage From Unrolled Lightweight Block Ciphers: A Case Study of Power Analysis on PRINCE

Abstract

This study investigates a new side-channel leakage observed in the inner rounds of an unrolled hardware implementation of block ciphers in a chosen-input attack scenario. The side-channel leakage occurs in the first round and it can be observed in the later inner rounds because it arises from path activation bias caused by the difference between two consecutive inputs. Therefore, a new attack that exploits the leakage is possible even for unrolled implementations equipped with countermeasures (masking and/or deglitchers that separate the circuit in terms of glitch propagation) in the round involving the leakage. We validate the existence of such a unique sidechannel leakage through a set of experiments with a fully unrolled PRINCE cipher hardware, implemented on a field-programmable gate array (FPGA). In addition, we verify the validity and evaluate the hardware cost of a countermeasure for the unrolled implementation, namely the Threshold Implementation (TI) countermeasure.

Side-Channel Attack of Lightweight Cryptography Based on MixColumn: Case Study of PRINCE

“…The difference in inputs will be masked by the algorithm, and the difference will not be observed after a certain number of rounds. In [26], the authors proposed a leakage model based on differential inputs. All the aforementioned techniques aim to increase the SNR of the power consumption or the effectiveness and precision of the analysis phase.…”

“…In [23], the authors proposed an improved CFA [24] attack, which makes it feasible to extract first-order side-channel leakages from combinational logic in the initial rounds of unrolled datapaths. In [26], the authors were able to deepen the attack by using the intermediate values of the first round (i.e., the difference in switching), which showed up as a side channel leakage during the processing of the inner round. However, they were only able to recover all of the keys in the third round, and only 1/16 of the keys were recovered in the fourth round.…”

“…The chosen-input attack proposed in this paper can generate a difference of only 1 bit at the MixColumn output in the first round. The minimum difference in the first round decreases from 3 nibbles to 1 nibble as compared to [26], necessitating more rounds of iterations to completely mask this difference. Since only the input from the first round is used as the computational element, we are able to obtain the complete key information from the fourth round regardless of the protection of the first three rounds.…”

Experimental FIA Methodology Using Clock and Control Signal Modifications under Power Supply and Temperature Variations

“…However, there are new analysis techniques that do not attack the mathematical implementation of the algorithm itself, but the physical implementation of it. These analysis techniques are known as passive and active attacks [1][2][3][4][5][6][7]. Passive attacks are the so-called side channel attacks, which exploit physical leakages during encryption processes, such as power consumption, electromagnetic radiation, or timing, to reveal secret information, e.g., power analysis (PA) [1,2].…”

“…These analysis techniques are known as passive and active attacks [1][2][3][4][5][6][7]. Passive attacks are the so-called side channel attacks, which exploit physical leakages during encryption processes, such as power consumption, electromagnetic radiation, or timing, to reveal secret information, e.g., power analysis (PA) [1,2]. On the other hand, active attacks are any invasive or noninvasive attacks that exploit the information provided by cryptographic devices during an erroneous encryption or decryption process.…”