Method And Implementation For Partial Encryption Of JPEG2000 Images Based On EBCOT

As the Internet and multimedia technology develop greatly, more and more image information has been transmitted over the communication network, its confidential transmission and storage has attracted more and more attention. As such, a variety of encryption techniques have been introduced. At the same time, due to huge amount and high redundancy, real-time image encryption is very important. Therefore, real-time image encryption becomes an hot topic in the field of information security.Obviously, the traditional text encryption methods can be used to encrypt all data of image, but the encryption efficiency was very low. Thus, the encryption with compression has been introduced to encrypt compressed data, As a result, the quantity of image data is reduced, and the efficiency of encryption is improved. However, when real-time encryption is required, the compressed image data is still huge. Therefore, a new encryption method for encrypting only parts of the compressed data, namely partial encryption, was proposed recently. This method is an efficient solution for meeting requirements of both security and real-time encryption. The work in this thesis is an extension and expansion of the partial encryption. Since JPEG2000 standard is widely used, this thesis focuses on the partial encryption of JPEG2000 image.Specifically, this thesis proposes a new partial image encryption method based on the core algorithm EBCOT (Embedded Block Coding with Optimized Truncation) of JPEG2000 standard. The EBCOT arithmetic is essentially a bit-plane coder. Firstly, this thesis examines EBCOT and realizes the arithmetic. Then, its out-stream is classified into five categories based on EBCOT theory. Next, the effect of each type of data on image reconstruction is analyzed with the help of computer simulations. According to significance and the quantity of data, and taking the characteristic of wavelet transform into consideration, two typies of significant data are selected to encrypt. To verify the efficacy of the proposed method, this thesis carries out extensive computer simulations and security analyses with three kinds of the classical images, which are character, nature and veins. Computer simulations and security analyses results demonstrate that the proposed method can achieve high security by encrypting only 3-8 percent of EBCOT out-stream and do not change the compression rate. In order to apply the proposed image partial encryption method in practice, the software regarding partial encryption of gray level images is designed using VC. This software is a program of Windows based on MFC class libraries, it works in the Microsoft visual VC++ 6.0 develop environment. The software mainly achieves key generating, image encryption and image decryption, the interface is friendly. The test experiments show the correctness of the software.