4 ms·
The whole point of FHE is that the output (at the cloud server) is encrypted so that you can send it back to a client for decryption. Assuming an attacker isn’t
by meling 6y ago
The whole point of FHE is that the output (at the cloud server) is encrypted so that you can send it back to a client for decryption. Assuming an attacker isn’t in control of the client, there is nothing that would leak.
- Buttons840 6y agoSo, just as I can store an encrypted file in the Cloud and nobody can tell what it is, we can have a computation happen in the Cloud where nobody can determine what it is?
- meling 6y agoYes. But not only the data, also the algorithm isn’t visible to the computer doing the computing...
- xsamgreen 6y agoYou may be thinking of Indistinguishability Obfuscation. Current FHE algorithms (e.g. those undergoing standardization: https://homomorphicencryption.org/ https://homomorphicencryption.org/) don't provide IO. The compute provider knows the exact graph that is being computed, but, in the most secure scenario, they don't get to know the inputs and outputs of each node in the graph. The node operation (which can be only addition or multiplication) must be known to the compute provider so they can perform the correct mathematical transforms on the encrypted data.
- osaariki 6y agoExactly. And the magic is that now you can securely compute aggregations of data you've stored without having to download all of your data. Say you have some field in all of your encrypted, cloud-stored records and want to find the sum of all of them. With traditional encryption you'd either have to trust the cloud with your decryption key or download all of the records for local processing, which could be very slow. With homomorphic encryption you can instead have a cloud service do that computation without any visibility to the actual values and only have to download a single ciphertext containing the result.