3 ms·
Given that these instances are typically virtualized I wouldn't be surprised if you could extract a decent amount of entropy just by using the system timings (i
by simias 7y ago
Given that these instances are typically virtualized I wouldn't be surprised if you could extract a decent amount of entropy just by using the system timings (interrupts, RTC sampling etc...) given that they would be affected by the other running systems. And of course there's always the network card.
In my experience it's not usually super difficult to get a decent amount of entropy on complex desktop or servers, it's only a real issue on simple embedded hardware where you might have no way to sample the environment and all the timings are ultra-deterministic. In this case I've resorted to using temperature measurements and fan speed as a source of entropy during early boot, which isn't ideal.
- tinus_hn 7y agoIt would seem quite helpful if these virtual machines provided a virtual device that gives random numbers provided by the host device.
- pjc50 7y ago> given that they would be affected by the other running systems Philosophically, does that make it more or less random? The whole category of side-channels suggests that there are problems with sharing a system like this. There's also the philosophical question of how cryptographically secure a fully virtual system can be when the host has full inspection and control capability. If you're running in the cloud you need to think carefully about how to delegate this to the platform if at all possible.