An image-based key agreement protocol using the morphing technique

Abstract

Most traditional key agreement protocols are based on data exchange. In this paper, a novel key agreement protocol based on image exchange is proposed. In this protocol, the communication entities who want to establish a session key are pre-assigned a secret image by the registration center (RC) initially. In real-time communication, using this image as the source image, along with another image of her/his choosing as the target image, the entity creates a morphed image and transmits it to the other communication entity. At the receiver side, the entity de-morphs the received image using the same source image and recovers the target image. However, the recovered image is not completely the same as the original image because some pixels have been lost during the morphing process. Therefore, the relationship between the original image and the morphed image needs to be analyzed and the lost pixels are located accurately. By removing the lost pixels from the self-generated original image and the recovered image of the other entity, both communication entities can obtain the same information that can be used as the secret session key. This approach using the exchanged morphed image for establishing secret session key can conceal the purpose of the key distribution and therefore enhances its security. In addition, the exchange of the image between two entities provides intuitive information for communication entities.