Post-Quantum Security of Block Cipher Constructions
It addresses the largely unexplored post-quantum security of symmetric-key cryptography, providing rigorous proofs for practical constructions.
This work establishes foundations for post-quantum security of block ciphers and provides the first security proofs for key-length extension (FX), tweakable block ciphers (LRW, XEX), and many encryption/authentication modes, in both the plain and quantum ideal cipher models.
Block ciphers are versatile cryptographic ingredients that are used in a wide range of applications ranging from secure Internet communications to disk encryption. While post-quantum security of public-key cryptography has received significant attention, the case of symmetric-key cryptography (and block ciphers in particular) remains a largely unexplored topic. In this work, we set the foundations for a theory of post-quantum security for block ciphers and associated constructions. Leveraging our new techniques, we provide the first post-quantum security proofs for the key-length extension scheme FX, the tweakable block ciphers LRW and XEX, and most block cipher encryption and authentication modes. Our techniques can be used for security proofs in both the plain model and the quantum ideal cipher model. Our work takes significant initial steps in establishing a rigorous understanding of the post-quantum security of practical symmetric-key cryptography.