| With the further development of the networking, digitization and automation of the information technology, a large amount of secret information is constantly transmitted and exchanges with each other. So the information security requirements have become new and updated. Information security is the guarantee of the development of information technology and the development of information technology is the ultimate goal of information security. The information security technology based on the traditional cryptography has been very difficult to meet the complex and diverse needs in today’s security field. Information hiding technology has broken the camouflage thinking of traditional cryptography, which uses the redundancy characteristics of some carrier signal for secret information hiding and realizes the functions of secure communication, content authentication and so on. It can greatly improve the security of information system. On the basis of the analysis of the security risks of secret information transmission process of maritime ship-to-shore communication system, this paper designs and implements the information hiding technology based on chaos and transform domain and applies it to the concrete information hiding system. The main research contents of this paper are as follows:Firstly, based on the in-depth analysis of the security hidden trouble of the image information in the maritime ship-to-shore communication system, the overall framework of the information hiding system is designed, and the key technology of the system is described.Secondly, a geometric robust watermarking algorithm is proposed which is based on NSCT_SVD and correction technique. In this algorithm, the low frequency region is extracted from the carrier image by the nonsubsampled contourlet transform. The watermark is embedded by quantization of the Euclidean norm of each block singular value matrix, and then combined the characteristics of relative position invariant under geometric attack about the invariant centroid of image and the invariance of rotation and scaling attack about zernike moment, to carry out the geometric attack correction for carrier image and restore the watermark. Experimental results show that the algorithm has good robustness against common attacks and geometric attacks.Then, the integrity authentication of digital image is studied, and a fragile watermarking algorithm for image tamper localization based on double chaotic map and chaotic neural network is proposed. According to the Logistic and Lozi and chaotic neural network, the gray value of the original image are trained to form the final watermark, and the watermark is embedded into the LSB plane of the image, and then the watermark is extracted and used in the tamper localization experiment. The algorithm can accurately locate the tampered image with the initial parameters sensitivity, non periodicity of the chaotic neural network.Finally, the design and implementation of the system is completed according to the ship’s commu nication subsystem, and the mian functions of the system are given. The result of the preliminary application shows that the key technology of this paper is security and practicability. |
