Although slower, it feels like TFHE would provide better security against an active adversary. So, at least, simple server-side encrypted queries would well be possible
Can you explain how you would use FHE instead of garbled circuits in the Arx range query data structure? I don't see how that would work - wouldn't you have to (re-)introduce interaction to let the server learn intermediate results?
Although slower, it feels like TFHE would provide better security against an active adversary. So, at least, simple server-side encrypted queries would well be possible