Composable and Finite Computational Security of Quantum Message Transmission

Understand

Recent research in quantum cryptography has led to the development of schemes that encrypt and authenticate quantum messages with computational security.

• The security definitions used so far in the literature are asymptotic, game-based, and not known to be composable.
• We show how to define finite, composable, computational security for secure quantum message transmission.
• The new definitions do not involve any games or oracles, they are directly operational: a scheme is secure if it transforms an insecure channel and a shared key into an ideal secure channel from Alice to Bob, i.e., one which only allows Eve to block messages and learn their size, but not change them or read them.