Fully Homomorphic Encryption

Fully Homomorphic Encryption (FHE) enables arbitrary computation on encrypted data (ciphertext) without ever requiring the secret key, ensuring total data privacy during processing.

FHE is the cryptographic game-changer: it allows a third party (like a cloud server) to run complex operations—including additions and multiplications—on encrypted data and return an encrypted result that is correct upon decryption. This capability, first demonstrated by Craig Gentry in 2009, makes FHE Turing-complete for encrypted computation. While early implementations faced significant performance overhead (historically up to 10,000x slower), modern schemes like CKKS, BFV, and TFHE, supported by libraries like Microsoft SEAL and OpenFHE, are rapidly closing the gap. The technology secures outsourced computation, enabling privacy-preserving AI and analytics on sensitive data (e.g., healthcare records) while remaining quantum-resistant.

https://fhe.org