Cryptanalysis of Some Multimedia Encryption Schemes

Encryption is one of the fundamental technologies that is used in digital rights management. Unlike ordinary computer applications, multimedia applications generate large amounts of data that has to be processed in real time. So, a number of encryption schemes for multimedia applications have been proposed in recent years. We analyze the following proposed methods for multimedia encryption: key-based multiple Huffman tables (MHT), arithmetic coding with key-based interval splitting (KSAC), and randomized arithmetic coding (RAC). Our analysis shows that MHT and KSAC are vulnerable to low complexity known- and/or chosen-plaintext attacks. Although we do not provide any attacks on RAC, we point out some disadvantages of RAC over the classical compress-then-encrypt approach.