Sobre a Escolha de Permutações para Fins Criptográficos

Permutations play an important role in the field of data security, representing a substantial contribution to increase the diffusion of the encryption process and many cryptosystems make use of them . However, in general, the literature on the subject reports very few results concerning those aspects of a permutation that make it atractive for cryptographic purposes. In this paper the subject is considered and, in the search for cryptographically strong permutations to be used in private or public cryptosystems, the problem of counting the number of permutations of degree n that fix i elements is approached.