Comment by j2kun

Comment by j2kun 3 days ago

All modern HE schemes rely on post-quantum crypto. For example, the ring-LWE problem used by BFV is the same as Kyber (ML-KEM) but with different parameters.

The twist in FHE is that the server also has an encryption of the user's secret key, which adds an assumption called "circular security", and that's needed to do some homomorphic operations like key switching.

_verandaguy 3 days ago

Right on, thanks for the explanation!

So what gets called the "public key" in the blog post is just the (self?-)encrypted secret key from the user?

I'll read up on your other points after work -- appreciate the search ledes :)

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j2kun 3 days ago

The public key is also just like a normal public key, but the encrypted secret key is often called an evaluation key or a key switching key, or some other names. (It's also public in the security sense)

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