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Abstract

A hidden dimension of software and hardware security is secret-revealing information disseminated through side channels. Even the most secure systems tend to reveal their secrets through secret-dependent computation. Secret-dependent computation is detectable by monitoring a system's time, power, outputs, and electromagnetic signature. Common defenses to side channel emanations include adding noise to the channel or making algorithmic changes to eliminate specific side channels. Unfortunately, existing solutions are either, not automatic, not comprehensive, and/or not practical.We propose an isolation-based approach for eliminating power and timing side-channels that is automatic, comprehensive, and practical. Our approach eliminates side channels by leveraging energy harvesting techniques to isolate trusted computation from the rest of the system. Software has the ability to request a fixed-power and fixed-time quantum of isolated computation. By discretizing power and time, our approach controls the granularity of side channel leakage; the only burden on programmers is to ensure that all secret-dependent execution differences converge within a single power/time quantum.We design and implement three approaches to power/time-based quantization and isolation: a wholly-digital version, a hybrid version that uses capacitors for time tracking, and a full-custom version. A key insight we leverage is that capacitors act as resource efficient, workload and environment independent time trackers. We explore the trade-offs of the three designs and look at the challenges ahead.