Cryptology ePrint Archive: Report 2017/608

Your Rails Cannot Hide From Localized EM: How Dual-Rail Logic Fails on FPGAs

Vincent Immler and Robert Specht and Florian Unterstein

Abstract: Protecting cryptographic implementations against side-channel attacks is a must to prevent leakage of processed secrets. As a cell-level countermeasure, so called DPA-resistant logic styles have been proposed to prevent a data-dependent power consumption.

As most of the DPA-resistant logic is based on dual-rails, properly implementing them is a challenging task on FPGAs which is due to their fixed architecture and missing freedom in the design tools. While previous works show a significant security gain when using such logic on FPGAs, we demonstrate this only holds for power-analysis. In contrast, our attack using high-resolution electromagnetic analysis is able to exploit local characteristics of the placement and routing such that only a marginal security gain remains, therefore creating a severe threat.

To further analyze the properties of both attack and implementation, we develop a custom placer to improve the default placement of the analyzed AES S-box. Different cost functions for the placement are tested and evaluated w.r.t. the resulting side-channel resistance on a Spartan-6 FPGA. As a result, we are able to more than double the resistance of the design compared to cases not benefiting from the custom placement.

Category / Keywords: Side-Channel Analysis, Dual-Rail, Localized EM, Placement, Routing

Original Publication (in the same form): IACR-CHES-2017

Date: received 22 Jun 2017

Contact author: vincent immler at aisec fraunhofer de

Available format(s): PDF | BibTeX Citation

Version: 20170626:153312 (All versions of this report)

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