One-Way IND-CNA Key Setup - a Step Towards Provably Secure Symmetric Encryption

We analyse the consequences of the specific properties of the key-setup phase in symmetric encryption schemes for their security. We find that key-setup routines satisfying IND-CNA and one-wayness allow to construct schemes which are provably secure against key-recovery attacks. We propose a specific cryptosystem for which we show that the key-setup routine ensures a significant increase in the security of the scheme regardless of the possible attacks against the underlying cipher. The paper presents a proof, based on a set of assumptions, that the scheme remains secure even if a successful key-recovery attack against the underlying cipher is found.