Cryptanalysis of Shannon-Fano-Elias codes

Data compression techniques such as Shannon-Fano-Elias coding are often used in conjunction with cryptography. We discuss using Shannon-Fano-Elias codes for encryption. We focus mainly on the problem of deciphering a binary sequence that has been Shannon-Fano-Elias encoded. We show that if a cryptanalyst knows the source symbols and the probability mass function (PMF), then the Shannon-Fano-Elias coded sequences may be deciphered within a finite amount of time by exhaustive search. A simple strategy is introduced to prevent this type of eavesdropping