5 ms·

The key part is the first line in the abstract "Flush+Reload is a cache side-channel attack that monitors access to data in shared pages" The OS does not allo

by nn3 13y ago

The key part is the first line in the abstract "Flush+Reload is a cache side-channel attack that monitors access to data in shared pages" The OS does not allow arbitary programs to share pages with gpg. If you share pages with gpg you can already read the key directly, no need for any side channels. As far as I can tell the paper is completely pointless, a variant of this fallacy http://blogs.msdn.com/b/oldnewthing/archive/2009/01/21/9353310.aspx http://blogs.msdn.com/b/oldnewthing/archive/2009/01/21/93533...

tlb 13y ago
It does this with code pages, to trace the control flow. All modern OSes let you map code read-only (either static or shared libraries) into multiple processes while sharing the physical memory.
- nn3 13y ago
  The paper describes flushing the data pages. I don't see anything about the code pages in their algorithm.
  - tlb 13y ago
    It's confusing, but the "data" is instructions. It's explained in the first 4 paragraphs of section 5.
  - ris 13y ago
    It's a von neumann cache. The code is data. These people aren't idiots.
bigiain 13y ago
The OS isn't actually in control of that on a lot of cases these days - "Furthermore, as virtual machine hypervisors transparently share memory pages between VMs [5,19], the attack is applicable across the isolation layer between VMs"
- bcoates 13y ago
  Still, the abstract completely failing to mention that a RAM deduplicator in the hypervisor or guest is necessary to make the attack work is a big omission.