Digital Image Encryption Algorithm

With the rapid development of Internet technology and multimedia technology, themultimedia security has become a crucial issue that attracted much attention of both thegovernment and the public. Due to the intrinsic properties of multimedia such as highredundancy and bulk capacity, special concerns have to be made, which includesspeediness of operation, low computational overload, self-authentication of the data andnoninterference of the availability of data.In this dissertation, some issues in image encryption are studied and several chaosbased encryption schemes are composed as well, which are detailed as follows:(1) The summarization of the digital image encryption methods: Introduced thebackground of digital image encryption research, its application, present situation anddevelopment tendency. Classification and analysis have been done to the currentencrypfion algorithms.(2) Digital image encrypfion algorithm based on the chaotic block cipher: A newimage encrypfion algorithm based on chaotic output-cipher feedback block cryptosystemshas been proposed after summarized the current algorithms of gray value substitution anddiffusion. Experimental results showed that the algorithm achieved higher level of securityand faster speed with only iterate twice.(3) Digital image encrypfion algorithm based on the chaotic stream cipher: Introducedthe chaos pseudo-random binary sequence generation methods and proposed an imageencryption algorithm based on the perturbation realization CCS-PRBG. This algorithm hasrapid and high secure character.(4) Image encrypfion algorithm of JPEG: A new image encrypfion algorithm, whichcombined the coding process with JPEG image encrypfion process, has been proposedafter the research to the JPEG image encrypfion algorithm. This algorithm combines thedigital image compression and the encryption process, has given dual attention to theefficiency of compression and the encryption intensity, and has the very good practicality.