Security using Shannon-Fano-Elias codes

In this paper we propose using the compression method, Shannon-Fano-Elias coding, for encryption. Shannon-Fano-Elias codes lend themselves for encryption because code-words depend on the order in which the symbols that need to be coded are written and it does not matter if the probability mass function of the symbols is known to everyone. If there are n symbols then there are n! orderings, each leading to a new code. Using an ordering as a key for encryption for small n leads to a weak encryption scheme. We therefore propose a new scheme called adaptive Shannon-Fano-Elias code that makes the complexity of attacks exponential in m, where m is the length of the string being compressed. Since m is usually very large (> 2²⁰), the security of our scheme is very high. The main reason why our scheme´s security depends on m is the fact that all attacks require the ciphertext to be scanned from left to right.