关键词: 信息熵, 图像编码, 图像拼接, CRC 循环编码, 无载体信息隐藏 

Abstract: In this paper，a coverless information hiding method is introduced on the basis of image coding and splicing in order to improve effectively the security and efficiency of covert communication． Firstly， the image is divided into blocks，and the entropy of each block is calculated to construct an entropy matrix． The entropy matrix is quantized and then the mapping relation is constructed between the random number sequence and the image feature． Secondly， the random number sequence to be represented is divided into segments，and the correct images are extracted from the complete image database corresponding to the information segments． Finally，those selected images are spliced with a certain positional relationship． In this way，the stitching image is a secret carrier for transmission，which makes a high-efficiency covert communication with a coverless information hiding． Besides， the secret information is encoded with CＲC codes to improve the security． The experimental results show that the proposed algorithm has great tolerance of JPEG compression attack and salt ＆ pepper noise attack，and has a good performance of antisteganalysis． This method is significantly valuable in applying covert communication with low capacity and high security． 

Key words: information entropy, image coding, image stitching, CRC cyclic code, coverless information hiding