Research Of Image Encryption Algorithms Based On JPEG2000

As the Internet and multi-media technology develop greatly, multimedia communication has become a most important way to exchange the information between people. And, the information's security and encryption also become a hot and urgent topic. However, for the multimedia, especial for the image, the traditional encryption technology regards them as the common data stream without considering their features, so those algorithms are not very applicable for the multimedia.Focusing on JPEG2000 data structure's feature, this paper researched the encryption algorithms for JPEG2000 By analyzing JPEG2000 encoding and the existing image encryption, the encryption rule for JPEG2000 was found, that is an excellent JPEG2000 encryption algorithm should be good real-time, security, effect and should not decrease the compressing ration. So, the paper proposes two selective encryption algorithms based on JPEG2000. Firstly, for the specific structure of the JPEG2000 code stream, we only encrypt the few part of stream using an AES symmetric block cipher. And we find that encrypting 20% of the visual data is sufficient to provide a high level of confidentiality. Secondly, because the core for JPEG2000 encoding is DWT transforming, and the most of energy of image is focused on the low frequency coefficients after transformation. So we only encrypt the low frequency coefficients of wavelet decomposition, chaotic sequence is adopted as encryption cipher. And encryption/decryption process is inserted into the JPEG2000 encoding/decoding system to improve the performance of the whole system.By simulating these algorithms with software, the experimental data showed that encryption did not increase JPEG2000 CODEC'S burden, since it was carried out at the same time as c coding/decoding, meanwhile, it has good encrypting effect, safe, and does not decrease compressing ration, Therefore, It is proved to be an effective encryption/decryption resolution for JPEG2000.