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Fully homomorphic encryption and the dawn of a private internet

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Re: Fully homomorphic encryption and the dawn of a private internet

#41

Post by mynameismon »

utf_8x wrote: post #37

As someone who knows basically nothing about cryptography - wouldn't training an LLM to work on encrypted data also make that LLM extremely good at breaking that encryption? I assume that doesn't happen? Can someone ELI5 please?

From my understanding of cryptography, most schemes are created with the assumption that _any_ function that does not have access to the secret key will have a probabilistically small chance of decoding the correct message (O(exp(-key_length)) usually). As LLMs are also a function, it is extremely unlikely for cryptographic protocols to be broken _unless_ LLMs can allow for new types of attacks all together.

Re: Fully homomorphic encryption and the dawn of a private internet

#43

Post by orwin »

I interrupted this fascinating read to tell that "actually", quantum computers are great at multi-dimensional calculation if you find the correct algorithms. It's probably the only thing they will ever be great at. You want to show that finding the algorithm is not possible with our current knowledge.

anyway, making the computer do the calculation is one thing, getting it to spew the correct data is another.... But still, the article (which seems great at the moment) brushes it of a bit too quickly.

Re: Fully homomorphic encryption and the dawn of a private internet

#44

Post by tsimionescu »

zkmon wrote: post #39

What baffles me is, how can code perform computations and comparisons on data that is still encrypted in memory.

It's simple conceptually: you find an encryption method Enc that guarantees `Sum(Enc(x), Enc(y)) = Enc(Sum(x, y))`. That's ultimately all there is to it. Then, you give the server enc_x and enc_y, the server computes the sum, and returns to you enc_sum. You then decrypt the value you got and that's x+y.

Since lots of functions behave in this way in relation to sums and products, you "just" need to find ones that are hard to reverse so they can be used for encryption as well.

Unfortunately this turns out to not work so simply. In reality, they needed to find different functions FHESum and FHEMultiply, that are actually much harder to compute (1000x more CPU than the equivalent "plaintext" function is a low estimate of the overhead) but that guarantee the above.

Re: Fully homomorphic encryption and the dawn of a private internet

#45

Post by 4gotunameagain »

utf_8x wrote: post #37

As someone who knows basically nothing about cryptography - wouldn't training an LLM to work on encrypted data also make that LLM extremely good at breaking that encryption? I assume that doesn't happen? Can someone ELI5 please?

Because math. The data that would be necessary to train an LLM to break (properly) encrypted information would be indistinguishable from random bytes.

How do you train a model when the input has no apparent correlation to the output ?

Re: Fully homomorphic encryption and the dawn of a private internet

#46

Post by strangecasts »

utf_8x wrote: post #37

As someone who knows basically nothing about cryptography - wouldn't training an LLM to work on encrypted data also make that LLM extremely good at breaking that encryption? I assume that doesn't happen? Can someone ELI5 please?

Good encryption schemes are designed so that ciphertexts are effectively indistinguishable from random data -- you should not be able to see any pattern in the encrypted text without knowledge of the key and the algorithm.

If your encryption scheme satisfies this, there are no patterns for the LLM to learn: if you only know the ciphertext but not the key, every continuation of the plaintext should be equally likely, so trying to learn the encryption scheme from examples is effectively trying to predict the next lottery numbers.

This is why FHE for ML schemes [1] don't try to make ML models work directly on encrypted data, but rather try to package ML models so they can run inside an FHE context.

[1] It's not for language models, but I like Microsoft's CryptoNets - https://www.microsoft.com/en-us/research/wp-content/uploads/... - as a more straightforward example of how FHE for ML looks in practice

Re: Fully homomorphic encryption and the dawn of a private internet

#47

Post by redleader55 »

Full homomorphic encryption is not the future for private internet, confidential VMs are. CVMs are using memory encryption and separation from the host OS. ARM has TEE, AMD has SEV and Intel has been fumbling around with SGX and TDX for more than a decade.

Re: Fully homomorphic encryption and the dawn of a private internet

#48

Post by udev4096 »

redleader55 wrote: post #47

Full homomorphic encryption is not the future for private internet, confidential VMs are. CVMs are using memory encryption and separation from the host OS. ARM has TEE, AMD has SEV and Intel has been fumbling around with SGX and TDX for more than a decade.

https://sgx.fail

Re: Fully homomorphic encryption and the dawn of a private internet

#49

Post by strangecasts »

paulrudy wrote: post #16
pluto_modadic wrote: post #14

Earlier quoted context omitted.

a simple example of partial homomorphic encryption (not full), would be if a system supports addition or multiplication. You know the public key, and the modulus, so you can respect the "wrap around" value, and do multiplication on an encrypted number. other ones I imagine behave kinda like translating, stretching, or skewing a polynomial or a donut/torus, such that the point/intercepts are still solveable, still unk…

Thank you. So based on your examples it sounds like the "computation" term is quite literal. How would this apply at larger levels of complexity like interacting anonymously with a database or something like that?

There are FHE schemes which effectively allow putting together arbitrary logical circuits, so you can make larger algorithms FHE by turning them into FHE circuits -- Jeremy Kun's 2024 overview [1] has a good summary

[1] https://www.jeremykun.com/2024/05/04/fhe-overview/ - discussed previously: https://news.ycombinator.com/item?id=40262626

Re: Fully homomorphic encryption and the dawn of a private internet

#50

Post by palata »

kube-system wrote: post #23
haiku2077 wrote: post #12

Earlier quoted context omitted.

You're not joking. If you're like most people and have only a few TiB of data in total, self hosting on a NAS or spare PC is very viable. There are even products for non-technical people to set this up (e.g. software bundled with a NAS). The main barrier is having an ISP with a sufficient level of service.

Sure, hardware is cheap. However if you actually follow the 3-2-1 rule with your backups, then you need to include a piece of real estate in your calculation as well, which ain’t cheap.

If you self-host your NAS, then your server has access to the data in clear to do fancy stuff, and you can make encrypted backups to any cloud you like, right?
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