alt Hacker NewsMaybe I'm not understanding this, but how is it that you can know enough about the data to process it without undermining the fundamental concept of encryption? Isn't encrypted data supposed to be just random noise without the key? The more you know about the underlying data the easier it gets to decrypt? Does this mean someone can just steal your encrypted data and use that to steal your identity without even needing to decrypt it anymore?
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this isnt about the progress of FHE, this is about models hiding reasoning traces (i.e. "thinking") from their paying customers because they dont want them knowing how question A got to answer B.
you can produce a correct result without knowing what that result means as long as the person you then provide that result to can decrypt it. So the way it works is the server does the job on data it can't read, sends an answer to the device, the device decrypts it.
It's very useful for things like healthcare data for example but also for products like "home assistants", and it's one of the use cases that the team hiring internally was giving in their job req. I tried to apply too but didn't get it unfortunately, this was a very interesting product to work on imho, congrats to whoever got my job :)
the basic encryption scheme used here is fairly straightforward actually, at least the symmetric encryption version. Let s be a uniformly random, 512-dimensional u32 vector. To encrypt a message m (say a 512-dimensional bit vector for simplicity), you
1. generate a 512 x 512 random (u32) matrix A, and
2. generate a 512-dimensional rounded (to the nearest integer) Gaussian, say of standard deviation 10, e.
The ciphertext is then [A, b :=As + e + 2^8 m].
To decrypt, you compute b - As to recover 2^8 m + e. You can then recover m, as e << 2^8 with high probability.
Anyway, if you have two of these ciphertexts, you can sum them together to get
[A1 + A2, (A1 + A2)s + (e1 + e2) + 2^8 (m1 + m2)]
this decrypts to m1 + m2, so you can recover homomorphic sums (or scalings by small integers).
Multiplication is more complex, so I won't get into it here. But the high level from the above example is that you could have someone compute arbitrary linear functions of your data without them knowing what your data is.