Image Steganography Based On Lifting Wavelet Transform

Information hiding technology is a kind of information security technology and develops very fast in recent 10 years. Nowadays, in the information technologies, it has become a hot spot especially with the high-speed Internet development.How to protect the security of important information of us in the public Internet? The traditional method is to encrpt the secret data with encrptography technology. Always the encrypted data is a kind of unregular and scrambled state, and so is easy to be attacted. Also, this encryption becomes more and more unsecure because the increasment of it's security key length can not fight against the crazy increasment of computers'computing capacity. While, the information hiding technology can provide a new way to protect our secret data.Steganography is a very important branch of information hiding. The aim of steganography is to hide the secret information in the public cover signals, especial in Internet. It uses the visual and hearing redundancy of our human beings, the statistical redundancy of multimedia digital siganals and the format redundancy of internet medias, and so in a special way, embeds the secret information which is encoded, modulated, or encrypted in public signals. The good covery of huge public internet multimedia data, and the embedding methods, steganography can secure the communications security of our political, military, economic information, and will be applicated broadly.This paper introduces the fundamental theories, history, development, technical classification of information hiding, especially the steganography's state of art development. The paper emphasizes the Least significant bit(LSB) serial and random replacement steganography methods and the coorespongding steganalysis technologies. By deeply analyzing the above theories,and with discussing the lifting wavelet transform characteristics, a new steganography methos is provided against the detection methods nowadays. On the basis of this method, a new watermarkingalgorithm is provided too. The followings are the magor work:1. a new steganograhy method based on lifting Haar wavelet transform and LSB match is provided. Spatial LSB match steganography method is very good one in preserving the one-class statistical characteristic and only makes little change in image data. Utilizing this thought, we introduce it in image transform field. We also know, the wavelet thransform has many special merits in image computing. And also, in transform field, the secrete data embedding can be thought as a kind of noise to avoid the three parts'suspicion. Lifting wavelet transform outstands traditional wavlet transform in computing speed. So, in theory, this method should have low computing complexity and good security. With the Primary Set Steganalysis method's detect, the detecition rate is very low even in 100% embedding condition. The results prove the efficiency and security.2. a watermarking method based on lifting wavelet transform is provided. The method also utilizing the wavelet high phrequency coefficients'merits in hiding watermarkings, and the transform fields outstand spation fields against watermarking attact. By Jpeg encoding attact with different encoding factors, the extracted bit stream is compared with the original watermarking stream. Results show the good robustness when the encoding factors are more than 40. Steganography is already paid much attention now, but it has also many problems to be solved. Frow our study point, we think the future work may include: the security definition of steganography, how to provide more effective methods; the steganalysis also needs rapid development to advance the steganography development.The relationship of steganography and steganalysis is like the one of mouse and cat, so their fights will be restricted and advanced each other. Research on this field is a hard work, it will go on unceasingly and deeply.