achamayou's comments

achamayou | 6 years ago | on: V0LTpwn: Attacking x86 Processor Integrity from Software

No, the user is still in control of what they execute on the machine, whether it is run in enclave or not. If anything, because it is deliberately unable to patch itself, software running in an enclave gives more control and auditability to a user who can know exactly what code they are running.

Importantly, a user who does not fully trust the machine administrator can still maintain integrity and confidentiality over their computation.

SGX memory encryption keys are ephemeral, they are generated at boot, and they do not need to be owned by anyone to be useful, on the contrary!

achamayou | 6 years ago | on: V0LTpwn: Attacking x86 Processor Integrity from Software

I don’t think it’s helpful to confuse side-channel or micro-architectural attacks with attacks on SGX itself. Stating that hardware enclaves don’t work and do not ship is absurd, they are present in virtually every modern phone for one thing.

Code running in an SGX enclave is measured and absolutely known at enclave launch. The fact that enclave memory is encrypted for confidentiality is unrelated.

I don’t understand why you think trusting the hyper visor is helping anything. You are still open to this attack, and to all side channel attacks as soon as you run any untrusted code.

achamayou | 6 years ago | on: V0LTpwn: Attacking x86 Processor Integrity from Software

I’m not sure why you think that SGX shows hardware enclaves “don’t work”. I also don’t see why you think enclaves “protect the malware from you”. Enclaves are created and started from host code, which can interrupt or terminate them at any time.

The scheme you suggest, which isn’t typically how TrustZone is used, gives zero integrity and confidentiality guarantees for applications. I don’t know if it’s “the right way” for some threat model, but for the most typical TEE use cases which are trying to establish strong integrity and confidentiality guarantees in the presence of an untrusted host, it’s absolutely not right nor useful.

achamayou | 6 years ago | on: Too Much Food in the Wrong Places

How do you distribute it out freely without affecting the market price? If packaging and transport are a substantial part of the cost, which they are for milk, who’s going to pay that cost?

achamayou | 6 years ago | on: “Rule the Waves”: a game of naval strategy (2016)

A Type 45 destroyer is almost 10000 tons though, a WWII destroyer would have been 2 to 3000. It’s probably difficult to come up with an accurate cost comparison, but I suspect the difference is even greater than for tonnage.
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