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Cache side-channel attacks and speculative execution attacks that leak information through cache states are stealthy and dangerous attacks on hardware that must be mitigated. Unfortunately, defenses proposed for cache side-channel attacks do not mitigate all cache-based speculative execution attacks and vice versa. Since both classes of attacks must be addressed, we propose comprehensive cache architectures to do this.

We show a framework to analyze the security of a secure cache. We identify same-domain speculative execution attacks, and show they evade cache side-channel defenses. We present new hardware security mechanisms that address target attacks and reduce performance overhead. We design two Speculative and Timing Attack Resilient (STAR) caches that defeat both cache side-channel attacks and cache-based speculative execution attacks. These comprehensive defenses have low performance overhead of 6.6% and 8.8%.