Research On Key Techniques Of Mission Assurance

With the rapid development of information technology, information systems have become core components of modern products and services, as well as the dependence of the construction of critical infrastructure. Due to the vulnerability and unexpected operational functions of the information systems,this high dependence becomes a huge risk to the national critical infrastructure. In view of this, software assurance, system assurance and service assurance have been proposed in the field of assurance techniques to reduce uncertainty in the application process of the information technology and information systems, according to the development of the architecture of information systems.In addition to the continuous development of assurance techniques, information systems on the one hand are becoming increasingly large and complicated in the original technical framework, making that the failures (or accidents) become inevitable; on the other hand, the new organizational concepts and models continuously emerge, breaking the traditional geographical restrictions, organizational resources restrictions as well as structural constraints, and showing distribution,flattening, flexibility and autonomy. Therefore, information systems are increasingly presenting complexity, uncertainty and dynamism. Traditional assurance methods and techniques, based on reductionism, overemphasize the assurance from bottom to top.In the face of complex information systems, this approach is almost impossible to do everything and is unable to guarantee that complex information systems’ ability to implement the human will. Therefore, service assurance focuses more on the meaning of existence of information systems as service providers. This also indicates a new research direction for mission assurance, that is, to weigh the gains and losses of the system under the premise of the purpose of information system and on the basis of permitted attacks, faults and accidents, so as to achieve the purpose of the information system. Therefore, in the field of assurance techniques, the concept of "mission assurance" is proposed.Most relevant theses on "mission" and "mission assurance" appear in the documents of United States Department of Defense (DoD), focusing on giving execution units the ability to think about responsibility besides executing commands mechanically. In this way, the command execution units will be able to control the execution scope and extent of command, and aim for fulfilling the responsibility of the "mission" role of the task or action,rather than mechanically completing clear command. This view gives a good inspiration and research direction that safety issues should not be judged case by case in the management of information systems and safety engineering. All considerations regarding the system behaviors and security should be aimed for the purpose of information systems. Focusing on the mission assurance based on the purpose of information systems, main works and innovations of this paper can be summarized as follows:(1) Definitions of "mission" and "mission assurance" and the scope of study.Although the wording "mission assurance" has been mentioned in the field of assurance techniques, such study is still in the conceptual stage with less related technology researches and results. Even the pioneering US military only proposed fuzzy thought of "giving execution units the ability to think about responsibility besides executing commands mechanically". Therefore, in order to clearly set forth the scope of this study and provide reference for future research in this field, this paper firstly analyzes the meanings and roles of "purpose" and "objective", and then discusses the meaning of "mission assurance" and the scope of study. Based on that,a more comprehensive and practicable concept of "mission assurance" is proposed.(2) Study on mission assurance theory. The proposed mission assurance concept includes the purpose of the system besides traditional assurance technologies, and thus makes the well-defined assured object abstract, complex, ambiguous and difficult to be defined, which is easy to be split, quantified, measured, handled before. The methodology and way of thinking for existing information system will not be able to fully meet the needs of mission assurance. Therefore, this paper analyzes new changes and new security issues of the information system, and summarizes its theory models and methodological limitations. Based on that, this paper proposes accordingly mission assurance methodology, providing reference in thinking and methods for the purpose-based study on the security of information system.(3) Study on modeling method of mission assurance. The mission assurance is an engineering process to assure the purpose of the system, during which the influence of ness, complexity and subjectiveness of the purpose as well as the cognitive uncertainty outweigh the objective uncertainty. Based on the analysis of cognitive uncertainty and application of fuzzy theory, this paper proposes the method for quantifying the importance of the purpose of the system. This method combines subjective and objective information, weakens the exact numerical assumptions, and fully embodies the abstractness, complexity and cognitive uncertainty of the purpose in mission assurance scene. This study provides a reference for modeling the complex problems.(4) Study on mission planning method. This paper proposes the method for planning mission resources on the basis of quantifying the difficulty degree of mission achievement. This method on one hand pursues the maximum of mission contribution with limited possibility requirements; and on the other hand seeks the maximum of possibility with specific mission contribution, which respectively reflect the optimisticthinking and pessimistic thinking in the process of mission assurance. The new possibility measure proposed in the method eliminates the deficiencies that possibility measure and necessity measure cannot be used to count mission contribution, and extends the application scope of possibility measure. Although the proposed mission planning method is for resource planning scene, it can provide reference for the settlement of fuzzy planning problems and the like regarding the process of mission assurance.(5) Study on purpose-based dynamic game method. This paper studies the game method for mission assurance in a distributed attack and defense network scene. On one hand, the method bases on the concept of "appropriate security", and stimulates the attacker and defender to jointly safeguard the security balance of the information system by strategy optimization, and thus improves the quality of mission assurance.On the other hand, the method ignores partial, phased security gains and losses, and pursues the maximum of overall benefits according to the mission purpose. The proposed method fully embodies the "appropriate security" and "mission-based"concept, extends the game theory, and provides reference for the application of mission assurance in specific problem scene.In summary, this paper firstly gives the comprehensive and enforceable definition of mission assurance based on the distinction between "purpose" and"objective". This definition helps to standardize and guide the study direction of the field and research areas. According to the theoretical study of mission assurance, this paper proposes a purpose-based methodology study on the security of information system, enriching its existing methodology and the way of thinking. The proposed mission modeling, planning and game method are all centered on the purpose-driven concept in the process of mission assurance, and provide references for subsequent studies.