A jigsaw puzzle based secret key exchange scheme

In cryptography, how to distribute a secret key in a secure way is an important issue. In this paper, based on cryptographic and data hiding techniques, we propose a new and high secure secret key exchange scheme. In this scheme, a sender will embed his secret key on an image to form a jigsaw puzzle image, and the jigsaw puzzle image will be posted on his/her Web site. Then the receiver can download the jigsaw puzzle image to extract the secret key. The scheme provides three security levels. The first is that the secret key is encrypted using a public cryptosystem before embedding. The second is that the existence of the secret key will be concealed such that no one will doubt that any secret information is included. The third is that the man in the middle attack problem can be solved.