Digital Image Integrity Verification And Authentication Technology

The history of information security technology, which plays an important role in social activities, is very long. Presently, Information Security is developing fast since the changes of information's media, storage and transport method. Message integrity verification and authentication are important aspects of information security technology. Message integrity verification means to test whether the message received is identical with the one to be sent. Authentication means to test whether who has sent the message is identical with whom declared or not. Digital image is a special sort of message. Image Integrity is very important for many imaging applications, for example, news report, court probe, medical archiving of images, trusted camera and others. In addition, sender's authentication is needed on some occasions. In these cases, some digital image verification functions are very hard to be implemented by traditional information security technology. For example, the verification and location to the changed pixels of image are hard to implemented with traditional method.In this paper, a new method based on watermark, message digest and public key cryptography technology is proposed to verify image integrity and sender's authentication. We proposed two protocols: non-arbitrate protocol and arbitrate protocol. Non-arbitrate protocol is simple and easy to be implemented, and it is mostly applied on trusted sender and receiver. This protocol is implemented based on LSB watermark technology. Its highlight points are: the verification andauthentication data are embedded into the images' data, any changes of pixel values and changes in image size due to scaling or cropping as well as block swapping in images or corresponding block swapping between images can be detected and located, Logo image is unnecessary. Arbitrate protocol is applied in distrusted sender and receiver. It is more secure than non-arbitrate protocols: the copyright of image can be protected by the CA, can prevent all A² codes attack, such as I₀,I₁;S₁;R₀;T; can prevent message resend attack.Digital image integrity and authentication based on watermark technology is a challenge to us. May people take interest in it, and many methods have been found. But, there is a long way to reach the perfect goal.