Robert Dumitru (Ruhr University Bochum and The University of Adelaide), Thorben Moos (UCLouvain), Andrew Wabnitz (Defence Science and Technology Group), Yuval Yarom (Ruhr University Bochum)

In recent years a new class of side-channel attacks has emerged. Instead of targeting device emissions during dynamic computation, adversaries now frequently exploit the leakage or response behaviour of integrated circuits in a static state. Members of this class include Static Power Side-Channel Analysis (SCA), Laser Logic State Imaging (LLSI) and Impedance Analysis (IA). Despite relying on different physical phenomena, they all enable the extraction of sensitive information from circuits in a static state with high accuracy and low noise -- a trait that poses a significant threat to many established side-channel countermeasures.

In this work, we point out the shortcomings of existing solutions and derive a simple yet effective countermeasure. We observe that in order to realise their full potential, static side-channel attacks require the targeted data to remain unchanged for a certain amount of time. For some cryptographic secrets this happens naturally, for others it requires stopping the target circuit's clock. Our proposal, called Borrowed Time, hinders an attacker's ability to leverage such idle conditions, even if full control over the global clock signal is obtained. For that, by design, key-dependent data may only be present in unprotected temporary storage (e.g. flip-flops) when strictly needed. Borrowed Time then continuously monitors the target circuit and upon detecting an idle state, securely wipes sensitive contents.

We demonstrate the need for our countermeasure and its effectiveness by mounting practical static power SCA attacks against cryptographic systems on FPGAs, with and without Borrowed Time. In one case we attack a masked implementation and show that it is only protected with our countermeasure in place. Furthermore we demonstrate that secure on-demand wiping of sensitive data works as intended, affirming the theory that the technique also effectively hinders LLSI and IA.

View More Papers

DLBox: New Model Training Framework for Protecting Training Data

Jaewon Hur (Seoul National University), Juheon Yi (Nokia Bell Labs, Cambridge, UK), Cheolwoo Myung (Seoul National University), Sangyun Kim (Seoul National University), Youngki Lee (Seoul National University), Byoungyoung Lee (Seoul National University)

Read More

ASGARD: Protecting On-Device Deep Neural Networks with Virtualization-Based Trusted...

Myungsuk Moon (Yonsei University), Minhee Kim (Yonsei University), Joonkyo Jung (Yonsei University), Dokyung Song (Yonsei University)

Read More

Automatic Insecurity: Exploring Email Auto-configuration in the Wild

Shushang Wen (School of Cyber Science and Technology, University of Science and Technology of China), Yiming Zhang (Tsinghua University), Yuxiang Shen (School of Cyber Science and Technology, University of Science and Technology of China), Bingyu Li (School of Cyber Science and Technology, Beihang University), Haixin Duan (Tsinghua University; Zhongguancun Laboratory), Jingqiang Lin (School of Cyber…

Read More

Horcrux: Synthesize, Split, Shift and Stay Alive; Preventing Channel...

Anqi Tian (Institute of Software, Chinese Academy of Sciences; School of Computer Science and Technology, University of Chinese Academy of Sciences), Peifang Ni (Institute of Software, Chinese Academy of Sciences; Zhongguancun Laboratory, Beijing, P.R.China), Yingzi Gao (Institute of Software, Chinese Academy of Sciences; University of Chinese Academy of Sciences), Jing Xu (Institute of Software, Chinese…

Read More