Unequal Security Protection: A Unified Framework, Implementation, and Performance Evaluation of Theoretical and Practical Security

Due to time constraints in real-time applications, it is sometimes impossible to encrypt the whole secret message with the same sophisticated encryption scheme. We propose unequal security protection (USP) as the solution. In the USP framework, a more sophisticated scheme, such as AES, is used to encrypt the more important parts, and a less complicated one is used for those with lower priority. We propose three specific designs, which are AES/XOR, AES/RC4, and AES/RC4/XOR, employing AES, RC4, as well as a secret mixing technique derived from the works in secure network coding. To evaluate and compare the three designs with one another as well as with the pure AES scheme, we extend the treatment of "Theoretical Security" and "Practical Security" to a wider class of situations in which a particular enciphering method can be said to provide both theoretical security and practical security with varying amount of secrecy. We also give implementation results regarding the encryption and decryption time of the proposed systems.