Selective Encryption Techniques of JPEG2000 Codestream for Medical Images Transmission

In this paper, novel selective encryption image schemes based on JPEG2000 are proposed. The first one encrypts only the code-blocks corresponding to some sensitive precincts. In order to improve the security level we introduce the permutation of codeblocks contributing in the selected precincts. The idea of combining permutation and selective encryption is used in order to minimize the amount of processed data encryption while ensuring the best possible degradation through the permutation. Many of proposals format compliant encryption schemes for JPEG2000 that have been made encrypt packet body data, but leave header packet in plaintext. The second approach, combines code-blocks data encryption to a cyclic permutation of all packets headers in the bitstream. Actually, in the JPEG2000 codestream, packet header information is specific to the visual content, and it is can be used as a fingerprint of the codestream. Symmetric encryption AES with CFB mode is used to encrypt in the two schemes. The proposed schemes don’t introduce superfluous JPEG2000 markers in the protected codestream, i.e, its format is compliant to JPEG2000 codestream one. It keeps file format and compression ratio unchanged and doesn’t degrade the original error robustness. The proposed scheme works with any standard ciphers and introduces negligible computational cost. Key-Words: Communication system security, JPEG2000 Compression, Selective Encryption, permutation, medical images, Computer applications.