A Quantum-Classical Scheme towards Quantum Functional Encryption
This work addresses a gap in quantum encryption for functional access, which is incremental as it builds on existing quantum encryption and functional encryption concepts.
The paper tackles the problem of enabling different key holders to learn specific functions of the plaintext from a ciphertext in quantum encryption, proposing a novel one-bit secret-key quantum encryption scheme with a classical extension that allows learning different length subsequences, and proves its security under quantum semantic security, quantum entropic indistinguishability, and functional encryption definitions.
Quantum encryption is a well studied problem for both classical and quantum information. However, little is known about quantum encryption schemes which enable the user, under different keys, to learn different functions of the plaintext, given the ciphertext. In this paper, we give a novel one-bit secret-key quantum encryption scheme, a classical extension of which allows different key holders to learn different length subsequences of the plaintext from the ciphertext. We prove our quantum-classical scheme secure under the notions of quantum semantic security, quantum entropic indistinguishability, and recent security definitions from the field of functional encryption.