Once again, if you believe this is a real issue, you're logically enjoined from using practically any hardware cryptography, including the AES instructions or any HSM.
Moreover, if you're serious about having a problem with rdrand, you really can't be doing crypto on the x86 platform (putting you between a rock and a hard place, owing to that HSM injunction) --- that's because you don't actually know what the microarchitecture of the x86 platform is. It's far more complicated than the instruction set, or even what's documented in the PRM.
Aciicmez was able to recover keys from an Intel branch target buffer (the branch prediction cache). Did you know what the BTB was before I wrote this? Well, the BTB is public knowledge. How many microarchitectural features are there on the platform that aren't public knowledge? Probably lots. Not being a tinfoil hat type, I tend not to believe that any of these are malicious. But if you think rdrand is a plot by the NSA, you are a tinfoil hat type, and so let me help you be consistent: you need to stop using AWS right now, and stop using x86 platforms to run your encryption code. The NSA can pay $50 to get a VM on the same AWS box as runs your VMs, and then use local side channels to siphon out your secrets.
(Actually, so can the Slovak Mafia, which is a reason to be leery of doing any crypto on AWS.)
If you can't tell, I think this whole kerfluffle about Linux using rdrand is pretty silly.
Moreover, if you're serious about having a problem with rdrand, you really can't be doing crypto on the x86 platform (putting you between a rock and a hard place, owing to that HSM injunction) --- that's because you don't actually know what the microarchitecture of the x86 platform is. It's far more complicated than the instruction set, or even what's documented in the PRM.
Aciicmez was able to recover keys from an Intel branch target buffer (the branch prediction cache). Did you know what the BTB was before I wrote this? Well, the BTB is public knowledge. How many microarchitectural features are there on the platform that aren't public knowledge? Probably lots. Not being a tinfoil hat type, I tend not to believe that any of these are malicious. But if you think rdrand is a plot by the NSA, you are a tinfoil hat type, and so let me help you be consistent: you need to stop using AWS right now, and stop using x86 platforms to run your encryption code. The NSA can pay $50 to get a VM on the same AWS box as runs your VMs, and then use local side channels to siphon out your secrets.
(Actually, so can the Slovak Mafia, which is a reason to be leery of doing any crypto on AWS.)
If you can't tell, I think this whole kerfluffle about Linux using rdrand is pretty silly.