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> Total Memory Encryption (TME) ... uses a single, CPU-generated key for all of memory; users can control the usage of TME in the boot-level firmware. A new sta
by pdkl95 8y ago
> Total Memory Encryption (TME) ... uses a single, CPU-generated key for all of memory; users can control the usage of TME in the boot-level firmware. A new standard ... MKTME ... supports different encryption settings ... at the page level, and more keys. Different keys can be used at the same time for different memory regions.
While using multiple keys has legitimate advantages for the user, it's also a step towards unbreakable DRM and other malware. It's easy to think about how a new technology is useful, but it is prudent to also consider how the technology might be used as a weapon.
Memory encryption has obvious niche uses, but seems slightly outside the common threat model for most people (users). The more likely use-case (for the average user) is probably user-hostile: DRM, "Denuvo"-style tamper resistance.
edit: Forgot to mention: the single-key variation (TME) can provide a lot of the user-focused benefits, without the DRM proliferation risk.
- amluto 8y ago> While using multiple keys has legitimate advantages for the user, it's also a step towards unbreakable DRM and other malware. No it’s not. With MKTME, the kernel can read all memory, ptrace still works, etc. I don’t even see how a future MKTME v2 would be useful for DRM.
- pdkl95 8y ago> the kernel can read all memory That's great, iff you have root-level access. > I don’t even see how a future MKTME v2 would be useful for DRM. Intel already tried that with SGX. (Intel's documentation for SGX was all about creating a "Trusted Computing" environment, using the old Palladium/NGSCB DRM-sense of "trusted".
- johncolanduoni 8y agoThe difference is that SGX was explicitly designed to protect memory/execution from kernel access, and TME doesn’t have such a facility or any path I can see towards becoming one.
- amluto 8y ago> That's great, iff you have root-level access. And if you don’t have root access, then you can’t read other users’ memory. The MMU must be an evil scheme for DRM!
- zaarn 8y agoTME doesn't help much against local attackers, the memory controller isn't smart enough for that (yet), especially because the hypervisor still controls the keys. It does however help to mitigate a number of attacks such as freezing memory to extract encryption keys and similar.
- monocasa 8y agoYep. Full memory encryption formed the basis of the Xbox360's security, and other than one exploit that was patched pretty quickly, it needed a reset glitching attack to add unsigned code execution.
- deleted 8y ago[deleted]
- eridius 8y agoHow much DRM today is broken because of attacks on in-the-clear memory? I didn't think that was a standard way to attack DRM.