Deck‐function‐based Cryptography
Joan Daemen · 2023
Because of the split in block ciphers and provably secure modes, the assurance of block-cipher-based cryptographic schemes can be fully based on public scrutiny oft he block cipher with respect to its pseudorandom permutation (PRP) or secure pseudorandom permutation (SPRP) security. Cryptanalysts can focus their efforts on trying to find attacks that distinguish the block cipher from a random permutation in the simple scenario of having query access and a fixed unknown key. During the last decade, a field of permutation-based cryptography has appeared that, similarly to block-cipher-based crypto, defines modes and constructions on top of permutations. Informally, deck functions are keyed cryptographic functions that have an arbitrary-length input, can generate an arbitrary-length output and are efficiently extendable. A deck function can be used as stream cipher by taking a nonce as input and the output as keystream.