• Announcement: Apple announces a new open source Swift package for homomorphic encryption - swift-homomorphic-encryption.
• What is Homomorphic Encryption: It enables computation on encrypted data without revealing unencrypted data. Allows clients to send encrypted data to a server which operates on it and returns a decryptable result. The server never decrypts original data or has access to decryption key.
• Usage in iOS 18: In the new Live Caller ID Lookup feature, it uses homomorphic encryption to send encrypted queries to a server without the server knowing the specific phone number. live-caller-id-lookup-example provides a functional example backend.
• Package Features: Takes advantage of Swift on Server features like Hummingbird HTTP framework and cross-platform support, easy benchmarking with Benchmark library, and performant low-level cryptography primitives in Swift Crypto.
• Live Caller ID Lookup and PIR: Relies on Private Information Retrieval (PIR). A trivial PIR implementation is to send the entire database to the client. But the implementation using homomorphic encryption only needs to sync a small amount of database metadata.
• BFV HE Scheme: The Swift implementation of homomorphic encryption implements the Brakerski-Fan-Vercauteren (BFV) HE scheme. BFV is based on the ring learning with errors (RLWE) hardness problem and is quantum resistant. The Live Caller ID Lookup feature requires BFV parameters with post-quantum 128-bit security.
• Basic Example: Shows how to use Swift Homomorphic Encryption with choosing encryption parameters, performing pre-computation, encoding values, generating a secret key, encrypting plaintext, and decrypting ciphertext.
• Looking Forward: Encourages others to contribute and file issues at the respective GitHub repositories if they encounter problems or have suggestions. Excited to see how homomorphic encryption can enable new use cases.