Rearch On High Capacity Information Hiding Algorithm

As the rapid development of computer network technology and information science,information technology has brought great convenience to people's lives, but it also exposed more and more security risk issues. During the information transmitting, it is easier for illegal wiretapping, distorting, interception or attacking than ever before, which would harm the interests of users who used the network. However, because information hiding is an effective means of information security and information hiding can guarantee the security of information which was deliverring on the network.information hiding caused a great concern. Information hiding technique ensure the security of information transmission via hidding the existence of the information. It can be used to solve the problem of cryptography suffering attacks easilyCurrently,information hiding has been conducted extensive research. many scholars have put forth a lot of information hiding algorithm. At the same time,the high capacity of information hiding algorithms has get a lot of concern. The capacity of information,invisibility and the robustness are of the mutual influence and constraint each other.The main work of the dissertation is to study about how to embed information in the case of large capacity and at the same time to improve the quality and invisibility of steoimage.Firstly, the dissertation introduced the theory of information hiding on digital image and reviewed the basic concepts and principles of information hiding.It research mainly on large-capacity of information hiding algorithm and aslo made a further analysis. It has proposed two information hiding algorithms as followings:(1) A information hiding algorithm base on string matchingUsing seeds to control the random function in order to generate a series of random strings, and the length of the seed determines the number of random strings and also determined the times of string matchings. Hidden strings XOR with random strings respectively, which result in a range of different matching strings. Then match the carrier strings with each of the matching strings, and combined with the characteristics of bit planes to determine the weight of each carrier image pixel bits,calculated the amount of modifier that come from matching string embedded into the carrier strings. Then the matching strings which have the smallest amount of modifier were embedded into the carrier,and the seeds that generate matching strings would be embedded into the carrier,which used to revert the hidding information into the state that were changed before. In this way,it achieve high capacity in the information embedding to minimize modifications to the carrier image, which improved the quality of stego image. Using the string matching algorithm can embed information into multiple bit-plane,even can embed a maximum of 4 bits of secret information for each pixle that include 8 bits into a byte. The experiment shows that the algorithm can effectively reduce the distortion of carrier image.It can embed large amounts of information in the carrier, but also can maintain a high PSNR of carrier image.(2) Proposed a information hiding algorithm based on genetic algorithm.In order to reduce the visual distortion effect of the stego image, It introduced the genetic algorithms to find the best way of embedding secret information into cover image. Genetic algorithm is good way of solving the problem of global optimization, using the peak signal noise ratio as the fitness function of genetic algorithm, and according to the characteristics of secret information, designed the global search performance and take into account the complexity of the algorithm of adaptive crossover and mutation Operator, both theoretically and experimentally demonstrated its global optimization ability and take according to the requirements of the fitness function, which greatly improved the quality of the image after hidding information into the cover.According to the proposed hiding algorithm, a large number of experiments have been made. The data embedding process and the extraction of secret information were tested effectively. Experiments show that the proposed algorithm can hide a large amount of information, and also can keep the good quality of the stego images. especially in the visual effects there are some advantages. Secret information extraction rules can achieve blind extraction.