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