Abstract. Simultaneous multithreading ¡ª put simply, the shar-ing of the execution resources of a superscalar processor betweenmultiple execution threads ¡ª has recently become widespread viaits introduction (under the name ¡°Hyper-Threading¡±) into IntelPentium 4 processors. In this implementation, for reasons of ef-ficiency and economy of processor area, the sharing of processorresources between threads extends beyond the execution units; ofparticular concern is that the threads share access to the memorycaches.We demonstrate that this shared access to memory caches pro-vides not only an easily used high bandwidth covert channel be-tween threads, but also permits a malicious thread (operating, intheory, with limited privileges) to monitor the execution of anotherthread, allowing in many cases for theft of cryptographic keys.Finally, we provide some suggestions to processor designers, op-erating system vendors, and the authors of cryptographic software,of how this attack......
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Approximate Word Count: 4221
Approximate Pages: 17 (260 words per double-spaced page) |