Certified Side Channels

TL;DR

This paper shows that the way private keys are stored affects side channel security, revealing vulnerabilities in common software libraries and demonstrating practical key recovery attacks using various side channel signals.

Contribution

It uncovers how key storage formats influence side channel vulnerabilities and introduces new attacks exploiting these weaknesses across multiple signal types.

Findings

Different key formats lead to varying side channel vulnerabilities.

Vulnerabilities can cause disjoint arithmetic stacks within cryptosystems.

Practical key recovery attacks demonstrated using EM, cache, and timing signals.

Abstract

We demonstrate that the format in which private keys are persisted impacts Side Channel Analysis (SCA) security. Surveying several widely deployed software libraries, we investigate the formats they support, how they parse these keys, and what runtime decisions they make. We uncover a combination of weaknesses and vulnerabilities, in extreme cases inducing completely disjoint multi-precision arithmetic stacks deep within the cryptosystem level for keys that otherwise seem logically equivalent. Exploiting these vulnerabilities, we design and implement key recovery attacks utilizing signals ranging from electromagnetic (EM) emanations, to granular microarchitecture cache timings, to coarse traditional wall clock timings.