A scalable encryption method allowing backward compatibility with JPEG2000 images

A new method for encryption of JPEG2000 images, which is referred to as ´scalable encryption´, is proposed in this paper. The scalable encryption method makes the encrypted images have multi-level encryption and reduces the computational complexity of encryption, since different encryption algorithms can be simultaneously used in its procedure. Moreover, the encrypted images produced by the proposed method have complete compliance with JPEG2000, so that a standard JPEG2000 decoder can decode the encrypted images and the useful functionalities of the JPEG2000 codestream are preserved after the encryption. For example, the proposed method enables that content holders have no need of preparing two or more encrypted images for various users who are provided different access rights. In addition to this, the time for the encryption can be controlled by selection of adequate encryption algorithms for faster processing.