Side-Channel Analysis of AES Based on Deep Learning

Abstract: Side-channel attacks avoid complex analysis of cryptographic algorithms, instead they use side-channel signals captured from a software or a hardware implementation of the algorithm to recover its secret key. Recently, deep learning models, especially Convolutional Neural Networks (CNN), have been shown successful in assisting side-channel analysis. The attacker first trains a CNN model on a large set of power traces captured from a device with a known key. The trained model is then used to recover the unknown key from a few power traces captured from a victim device. However, previous work had three important limitations: (1) little attention is paid to the effects of training and testing on traces captured from different devices; (2) the effect of different power models on the attack’s efficiency has not been thoroughly evaluated; (3) it is believed that, in order to recover all bytes of a key, the CNN model must be trained as many times as the number of bytes in the key.This thesis aims to address these limitations. First, we show that it is easy to overestimate the attack’s efficiency if the CNN model is trained and tested on the same device. Second, we evaluate the effect of two common power models, identity and Hamming weight, on CNN-based side-channel attack’s efficiency. The results show that the identity power model is more effective under the same training conditions. Finally, we show that it is possible to recover all key bytes using the CNN model trained only once.