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How Stuff Gets eXposed

sgx.fail

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Re: How Stuff Gets eXposed

#41

Post by throw_a_grenade »

kelnos wrote: post #9
ccrush wrote: post #5

Good. This concept of continually restricting the owner of a processor from controlling the code that executes on his machine is a futile attempt at providing "products" which are nothing more than theft. The only reason this is a requirement for POWERDVD is because they insist on treating people like thieves and locking down the ability to watch high quality movies behind a wall that keeps the user from seeing and c…

> everyone should be ashamed for using Intel hardware when AMD chips do not abuse the user AMD has their own analog to Intel's Management Engine. Maybe they don't have SGX or something like it, but AMD is no saint either. In theory, SGX can be used for good: see Signal's use to avoid seeing users' contact lists. Granted, their scheme is pretty broken given how broken SGX is (and probably for other reasons), but I thi…

AMD has SEV: https://en.wikipedia.org/wiki/Zen_(first_generation)#Enhance...

It works on slightly different layer (virtualisation, not process), but the threat model and capabilities are pretty much the same.

Re: How Stuff Gets eXposed

#42

Post by stefan_ »

saagarjha wrote: post #37
stefan_ wrote: post #10

Earlier quoted context omitted.

These attacks on SGX are some of the most advanced attacks on any TEE ever. The crappy ARM smartphone vendor TEEs regularly fall apart from mere C bounds issues.

You're making an apple-to-oranges comparison between TEEs and SGX. The attacks on SGX here are on the processor/model of SGX itself. Buffer overflows are bugs in the applets that run inside the TEE. SGX applications can and do have similar bugs. Here's a random paper I found, there are many more: https://arxiv.org/pdf/2110.06657.pdf

Distinction without a difference, as far as the secrets are concerned. It means your claim "this is why you can't watch 4k on desktop" is dead and done.

Re: How Stuff Gets eXposed

#43

Post by tptacek »

lrvick wrote: post #35
tptacek wrote: post #28

Earlier quoted context omitted.

No. Virtually everything Signal has proposed to use SGX for, competing secure messengers simply store in plaintext databases already. Further, the fundamental security model of Signal is about what you don't send to Signal in the first place .

But SGX is almost no better than plain text, especially when centralized. At least solutions like Matrix give you the choice where your metadata is stored, and have never had a requirement for PII like phone numbers to worry about in the first place.

Matrix, the secure messenger where all messages are group messages, and servers control the group membership?

Re: How Stuff Gets eXposed

#44

Post by hayley-patton »

throw_a_grenade wrote: post #40
hayley-patton wrote: post #39

Quoth one of the pages of the Secret Network https://scrt.network/about/about-secret-network/ >: > Every validator on Secret Network runs their code inside a TEE so no one—not even the nodes operating on the network—can access the information being decrypted and processed. How could one possibly verify that a secure enclave is being used?

You do attestation. CPU has it's own private key [1] and signs a message saying what was the initial state of the enclave. Enclave can plug "user data" into this message, which almost always is a signature over a public key for TLS private key which was generated inside the enclave. Enclave presents it to the other side of encrypted connection (i.e. you). You verify the CPU's signature so the encrypted channel establ…

Thanks. How can the network tell that it is definitely communicating with a secure enclave, and not some kind of emulator? [1] suggests that keys and signatures from Intel are burnt into CPUs, which would work. All in all it's certainly an odd thing to put trust in.

[1] https://news.ycombinator.com/item?id=21840086

Re: How Stuff Gets eXposed

#45

Post by lrvick »

tptacek wrote: post #43
lrvick wrote: post #35

Earlier quoted context omitted.

But SGX is almost no better than plain text, especially when centralized. At least solutions like Matrix give you the choice where your metadata is stored, and have never had a requirement for PII like phone numbers to worry about in the first place.

Matrix, the secure messenger where all messages are group messages, and servers control the group membership?

Meanwhile Signal has a single stranglehold on the supply chain for client binaries that hold all decryption keys.

I will not deny you have made valid criticisms of the matrix protocol, but Signal has some very broken design choices as well. One of these is much easier to fix by motivated technical end users than the other.

At least in matrix a user choice of client codebase and binary can control which server they trust, and if they wish to automatically encrypt to new unverified room participants or not depending on their threat model. Technical users have total control over their rooms and the UX will improve for less technical users.

Also it is possible for someone to run the server daemon in a remotely attestable system like a Nitro enclave allowing it to prove to users what administrative features are enabled on a given server. This is something I am building foundations for right now.

Unlike Signal, any organization is free to run their own matrix servers with server-pinned channels adjusted for different threat models while still having access to the wider network. You get to choose the server that can decide your room membership, including choosing a server that does not grant a central administrator any significant trust.

If forced to pick between two flawed protocols, I will choose an open network controlled by democracy that gives individual users total freedom to make it better over a dictatorship for the long run.

Re: How Stuff Gets eXposed

#46

Post by Arathorn »

lrvick wrote: post #45
tptacek wrote: post #43

Earlier quoted context omitted.

Matrix, the secure messenger where all messages are group messages, and servers control the group membership?

Meanwhile Signal has a single stranglehold on the supply chain for client binaries that hold all decryption keys. I will not deny you have made valid criticisms of the matrix protocol, but Signal has some very broken design choices as well. One of these is much easier to fix by motivated technical end users than the other. At least in matrix a user choice of client codebase and binary can control which server they tr…

fwiw https://github.com/matrix-org/matrix-spec-proposals/blob/fay... is the ongoing work to solve the problem of server-controlled group membership. unfortunately it’s not a trivial problem in a decentralised network (which is why we punted it so far), but it’s starting to shape up.

Re: How Stuff Gets eXposed

#47

Post by throw_a_grenade »

hayley-patton wrote: post #44
throw_a_grenade wrote: post #40

Earlier quoted context omitted.

You do attestation. CPU has it's own private key [1] and signs a message saying what was the initial state of the enclave. Enclave can plug "user data" into this message, which almost always is a signature over a public key for TLS private key which was generated inside the enclave. Enclave presents it to the other side of encrypted connection (i.e. you). You verify the CPU's signature so the encrypted channel establ…

Thanks. How can the network tell that it is definitely communicating with a secure enclave, and not some kind of emulator? [1] suggests that keys and signatures from Intel are burnt into CPUs, which would work. All in all it's certainly an odd thing to put trust in. [1] https://news.ycombinator.com/item?id=21840086

Yes, the keys are kept in CPU itself. AFAIK Intel doesn't disclose the exact mechanism (blown fuses, EPROM or something entirely different).

You can't get valid quote outside the enclave, because CPU doesn't provide the instruction to sign the quote outside the enclave, and you can't calculate it youself, because you don't know CPU's private key.

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