Research On Entropy Random-Based Dynamic Covert Communication Over Network Streaming Media

Since the Internet permeates people's daily lives and is relevant to the needs of individuals,businesses and governments,there is an immense demand to address issues of data security and protection,and practical security protocols for evolving network applications are required.Streaming media like Voice over Internet Protocol(VoIP)across public networks are more prevalent among the applications.This thesis describes a theoretical and experimental investigation of secure covert communications over streaming media using dynamic steganography,which were studied using information theoretical modelling,security analysis,steganographic algorithm design,coding,covert communications testing,and performance and robustness measurement techniques.A covert VoIP communications system was developed to enable the work being carried out.The thesis provides new insights into how digital steganography and advanced cryptography such as advanced encryption standard and dynamic key distribution can work together to substantially improve the security,performance and robustness of steganographic systems,which acts as a covert VoIP communications channel to protect data from cyber attacks and even quantum adversaries.(1)A new information theoretical model of secure covert communications over streaming media was constructed to depict the security scenarios in streaming media-based steganographic systems with passive attacks.The model involves a stochastic process that models an information source for covert VoIP communications using streaming media steganography,the theory of hypothesis testing that analyses the adversary's detection performance,and a discrete prediction model of high precision that simulates the characteristics of time-variance of streaming payloads in covert communications over streaming media.(2)The potential of hardware entropy source based true random key generation and one-way cryptographical accumulator enabled dynamic key updating and transmission for innovative applications in the field of streaming media steganography and covert communications was explored in detail in this project.Ways in which hardware entropy sources can be used to generate true random numbers as secret keys for AES-128 encryption in covert communications using streaming media steganography,to ensure the data they protect remains absolutely secure,were investigated.Security analysis and M-W-W test showed that the secret keys generated by the true random number generator,using the Read Time Stamp Counter of the central processing unit as an entropy source,is unlikely to be broken by malicious attackers according to cryptography.(3)A dynamic key updating and transmission based steganographic algorithm that includes a one-way cryptographical accumulator integrated into dynamic key exchange for covert communications over streaming media,was devised to provide secure key exchange for covert communications over streaming media.The new algorithm can protect data from cyber attacks,such as the man-in-the-middle attacks,which threaten almost all existing steganographic algorithms.The discrete logarithm problem in mathematics and steganalysis using t-test indicates the algorithm has the advantage of being the most solid method of key distribution over a public channel.The effectiveness of the true random numbers and dynamic key updating and transmission based steganographic algorithm for covert communications over streaming media was examined by means of security analysis,steganalysis,non-parameter statistical testing,and performance and robustness measurements.The results indicated that this steganographic algorithm has no or little impact on real-time VoIP communications in terms of speech quality,signal distortion and imperceptibility,achieving the mean PESQ of 4.21 and the mean SNR of 44.87.It is more secure and effective in addressing the security problem associated with covert VoIP communications than other related algorithms,in that the average data embedding capacity up to 796 bps were comparable to those using the other algorithms.