Practical Protocol Steganography: Hiding Data in IP Header

Steganography is defined as the art and science of hiding information, which is a process that involves hiding a message in an appropriate carrier for example an image file. The carrier can then be sent to a receiver without anyone else knowing that it contains a hidden message. In this paper we present a novel scheme to send message imperceptibly between points over Internet. This scheme uses fourth-order Chebyshev chaotic system to generate chaos sequence which is used to encrypt secret message, and then embeds the modulated message into identification field of IP header. Compared with Ahsa´s scheme, this scheme can provide higher security. Furthermore, this schema allows sending covert message point to point by selecting proper IP packets according to path MTU discovery