A reliable and efficient micro-protocol for data transmission over an RTP-based covert channel

Abstract

As the VoIP steganographic methods provide a low capacity covert channel for data transmission, an efficient and real-time data transmission protocol over this channel is required which provides reliability with minimum bandwidth usage. This paper proposes a micro-protocol for data embedding over covert storage channels or covert hybrid channels developed by steganographic methods where real-time transport protocol (RTP) is their underlying protocol. This micro-protocol applies an improved Go-Back-N mechanism which exploits some RTP header fields and error correction codes to retain maximum covert channel capacity while providing reliability. The bandwidth usage and the performance of the proposed micro-protocol are analyzed. The analyses indicate that the performance depends on the network conditions, the underlying steganographic method, the error correction code and the adjustable parameters of the micro-protocol. Therefore, a genetic algorithm is devised to obtain the optimal values of the adjustable micro-protocol parameters. The impact of network conditions, the underlying steganographic method and the error correction code on the performance are assessed through simulations. The performance of this micro-protocol is compared to an existing method named ReLACK where this micro-protocol outperforms its counterpart.