The Application Of Image Hiding Technique In Information Security

With the drastic expand of Internet and multimedia technology; it is more and more convenient to transmit and spread multimedia information over Internet. Unfortunately, it also brings upon the information security problem. Information security technology is directly concerned with information security of a nation. If the secret information of some confidential departments is wiretapped, grievous harms would be done to the entire society. Moreover, it is also of utmost importance to preserve the commercial secrets of enterprises and individual privacy of correspondence. In recent years, image hiding is becoming a new research direction in multimedia communication and processing, so there are numerous unsolved problems, which hamper the actual implement of the technology. The key of image hiding technology is to investigate the robust data embedding method, which should maintain good perceptual quality for stego-image and have large embedding capacity, and be robust against intentional and unintentional attacks. Focusing on the above goal we studied the robust image hiding approaches in frequency domain. The following research has been accomplished.(1) The characteristics of various image-hiding methods in DCT domain were first analyzed. In order to improve the robustness, security, and embedding capacity of the existing approaches, we have carried out the following research. To overcome the grievous distortion problem due to distortions introduced in the secret image by rounding off errors, we proposed a new embedding scheme consisting of a reasonable partition of pixel value and a sign embedding operation. By incorporating fuzzy theory with human visual system (HVS), a fuzzy classifier for DCT sub-blocks was developed to realize the adaptive selection of the embedding strength. Moreover, the secret image for embedding was encrypted by exploiting the shuffling operations for pixel values and pixel positions based on chaotic cryptography. Finally, extensive experiments have been conducted to evaluate the performance of the proposed methods.(2) Color image is characterized of large amount of data, which brings difficulties in transmission and hiding by Internet. By extending the grey image hiding method in DCT domain, a robust color image hiding method based on YCbCr color system was developed and implemented.(3) Integral wavelet transform is a completely reversible transform with high fidelity. To further improve the embedding capacity of secret information in frequency domain and make compatible with the popular international image compression standard of JPEG-2000, we presented an image hiding method based on the Daub 5/3 lifting form of wavelet transform. This method allows inserting data adaptively in DWT domain.This research will shorten the distance between the image hiding theory and its practical application. It is of significance for secure information communication over Internet.