Apple has open-sourced the homomorphic encryption (HE) library it uses in its own deployments – making it available under an Apache 2.0 licence.
It shared details of its own implementation and a small handful of associated applications as a set of Swift libraries and executables.
Homomorphic encryption lets users run queries/compute on encrypted data without revealing the unencrypted data to the operating process.
Early implementations were clunky and often computationally prohibitive but that has changed in recent years and HE, a fascination of researchers for decades, is increasingly production ready. Examples of real-world applications have always been a little thinner on the ground, however.
Apple is using HE for Live Caller ID Lookup, for caller ID and spam blocking services, it said, announcing the library release. This lets Apple send an encrypted query to a server that can provide information about a phone number without the server needing to know/store the number.
The Swift implementation houses the Brakerski-Fan-Vercauteren (BFV) Homomorphic Encryption scheme, which is also quantum resistant.