Randomized, skewed caches (RSCs) such as CEASER-S have recently received much attention to defend against contention-based cache side channels. By randomizing and regularly changing the mapping(s) of addresses to cache sets, these techniques are designed to obfuscate the leakage of memory access patterns. However, new attack techniques, e.g., Prime+Prune+Probe, soon demonstrated the limits of RSCs as they allow attackers to more quickly learn which addresses contend in the cache and use this information to circumvent the randomization. To yet maintain side-channel resilience, RSCs must change the random mapping(s) more frequently with adverse effects on performance and implementation complexity. This work aims to make randomization-based approaches more robust to allow for reduced re-keying rates and presents Chameleon Cache. Chameleon Cache extends RSCs with a victim cache (VC) to decouple contention in the RSC from evictions observed by the user. The VC allows Chameleon Cache to make additional use of the multiple mappings RSCs provide to translate addresses to cache set indices: when a cache line is evicted from the RSC to the VC under one of its mappings, the VC automatically reinserts this evicted line back into the RSC by using a different mapping. As a result, the effects of previous RSC set contention are hidden and Chameleon Cache exhibits side-channel resistance and eviction patterns similar to fully associative caches with random replacement. We show that Chameleon Cache has performance overheads of < 1% and stress that VCs are more generically helpful to increase side-channel resistance and re-keying intervals of randomized caches.
翻译:CEASER-S 等扭曲的缓存(RSCs)最近受到许多关注,以抵御基于争议的缓存侧渠道。通过随机调整和定期将地址的映射改变为缓存套件,这些技术旨在混淆内存访问模式的泄漏。然而,新的攻击技术,例如Prime+Prune+Probe, 很快展示了RSCs的局限性,因为这些技术使攻击者能够更快地了解缓存中的争议,并使用这种信息绕过随机化。为了保持侧通道的复原力,RSC必须更经常地改变随机映射,对业绩和执行复杂性产生不利影响。这项工作的目的是使随机定位方法更加有力,以便降低内存存存访问访问模式的泄漏。Cameloon Cache, Cateleon Cache,让RSC 与用户观察到的拆迁离(VC)相比,让Celeanleon C的直流流流流流流流流流流流流系统更多地使用多盘路路路路路路路路路路路路路路路路路路路路路路路路段,让RS C的内变变变的内变变变变变的内。