Limitations on information theoretically secure quantum homomorphic encryption
This addresses a fundamental limitation in quantum cryptography for secure computation, indicating incremental progress by ruling out certain approaches.
The paper tackled the problem of achieving information-theoretically secure fully homomorphic encryption using quantum mechanics, and showed that deterministic schemes with perfect security incur exponential overhead.
Homomorphic encryption is a form of encryption which allows computation to be carried out on the encrypted data without the need for decryption. The success of quantum approaches to related tasks in a delegated computation setting has raised the question of whether quantum mechanics may be used to achieve information theoretically secure fully homomorphic encryption. Here we show, via an information localisation argument, that deterministic fully homomorphic encryption necessarily incurs exponential overhead if perfect security is required.