Access Control and Scalable Encryption Using a Stream Cipher for JPEG 2000 Encoded Images

The access control and scalable encryption scheme we propose for JPEG 2000 encoded images encrypts JEPG 2000 codestreams using the SNOW 2 progressive encryption algorithm to encrypt resolutions, quality layers, or packets independently to provide resolution, quality or fine-grain scalability. Access is controlled to different image resolutions or quality levels granted to different users receiving the same encrypted JPEG 2000 codestream but having different decryption keys. Keys used with successive resolutions or quality layers are mutually dependent based on the SHA-256 one-way hashing function. Encrypted JPEG 2000 codestreams are transcoded by an intermediate untrusted network transcoder, without decryption and without access to decryption keys. Our encryption scheme preserves most of the inherent flexibility of JPEG 2000 encoded images and is carefully designed to produce encrypted codestreams backward-compatible with JPEG 2000 compliant decoders.