Using Improved Shannon-Fano-Elias Codes for Data Encryption

We consider using Shannon-Fano-Elias codes for data encryption. In many applications both compression and security are required. If the cryptanalyst knows the code construction rule and the probability mass function of the source, then Huffman code provides no ambiguity, but Shannon-Fano-Elias coding is a good candidate since the ordering of symbols can be arbitrary in the encoding process, which produces super-exponential complexity for deciphering. Unfortunately, the conventional Shannon-Fano-Elias code has relatively large code length that makes it inefficient. In this paper, we propose two simple algorithms to reduce the expected length of Shannon-Fano-Elias codes. Experimental results on English text show that the proposed methods reduce the length by as much as 23.4%