Compressing Encrypted Data

The classical way of transmitting redundant data over a bandwidth constrained insecure channel is to first compress it and then encrypt. This report investigates the novelty of reversing the order of compression and encryption, without compromising either the encryption efficiency or the information secrecy. Although counter intuitive, principles from source coding with side information, can be used to make this reversal possible. In certain scenarios, no more randomness in key is required than the traditional system.