Differential and Linear properties of vectorial boolean functions based on chi

Abstract

To evaluate the security of a cryptographic primitive, investigating its resistance against differential and linear cryptanalysis is required. Many modern cryptographic primitives repeatedly apply similar round functions alternated with the addition of round keys or constants. A round function usually consists of a non-linear mapping and a number of linear mappings. The non-linear mapping χ is used in different cryptographic primitives such as KECCAK and SUBTERRANEAN. An alternative version of χ is used in ASCON and the non-linear layer of SIMON has the same differential and linear properties of χ. The mapping χ can be applied to strings with different lengths.