Guo Dong-hui

Digital Watermarking based on Non-Sampled Contourlet Transform

In this paper, a novel digital watermarking algorithm based on non-sampled contourlet transform (NSCT) is proposed. This algorithm gives a model of human visual system (HVS) in NSCT domain, exploiting the masking characteristics of HVS to embed watermark adaptively. NSCT has the characteristics of multi-resolution, localization, multi-directionality and anisotropy. Thus NSCT is much more similar to the information processing mechanism of the HVS than wavelet transform. Additionally, NSCT is a redundant transform, which can increase robustness to additive noise processing, and watermark can be considered as noise, it can be assumed that this algorithm can outperform the algorithm in wavelet domain. This assume is confirmed by experiments , compared to the algorithm in wavelet domain, this algorithm can embed much more watermark data, and the watermark is much more robust, achieved the best compromise between robustness and invisibility.

AES Algorithm Implemented for PDA Secure Communication with Java

Since Rijndael algorithm was selected as the AES (advanced encryption system) to substitute the DES (data encryption standard), the foremost concern for people has been its security. The result of new attack methods shows that there may be some lacuna in the design of S-box and key schedule with AES algorithm. The problem is the weakness of linearity existing in the S-box and key schedule. In order to keep from the new attacks and implement the AES for PDA secure communication in Java, we analyze in detail on the AES algorithm and give out a new implementation scheme for increasing complexity of nonlinear transformation in design of S-box. The experimental results show our implementation scheme with Java is feasible for the PDA application and is of an acceptable speed for data encryption and decryption.

STBC-MIMO Communication System for Image Encrypt via CNN

CNNs(cellular neural networks) are well-suited for parallel image processing. So CNN operations are normally used to the image encrypt and image transmission in wireless communication. In order to combat attenuation due to destructive addition of multi-path and due to interference from other users, in the paper, a novel scheme of multiple-input and multiple-output employing space-time block coding (STBC-MIMO) communication system combined with CNN image processing is presented, and STBC-MIMO system performance is analyzed. To examine the performance benefits of our proposed system, the simulation results are given in the end.