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Yes, it's still FHE, because the physical locations (e.g. RAM addresses, disk block indexes) don't reveal which logical index (in the FHE encrypted array) you a
by jlokier 5y ago
Yes, it's still FHE, because the physical locations (e.g. RAM addresses, disk block indexes) don't reveal which logical index (in the FHE encrypted array) you are looking up. The encrypted data isn't just shuffled in memory with a secret permutation, it's encoded in a way that's analogous to a hologram but with cryptographic operations.
- Dylan16807 5y agoI follow the idea that revealing the physical location is safe under a method like this. But how does the program tell the server which physical locations to grab? The knowledge of which locations are needed is inside the encryption.
- jlokier 5y agoAh. By using more complex FHE states and operations, such that part of the state can be decoded/decrypted by the server to direct the server's actions, while other parts remain opaque. The server may or may not find those decoded parts meaningful: Meaningful would be something like console output while the computation progresses, and a "finished" signal. Non-meaningful (but still useful to the FHE program) would be something that looks like a sequence of memory requests whose locations may as well be pseudo-random.