In multimedia consuming, Digital Rights Management (DRM) is the important means to con¯rm the bene¯ts of both digital contents/services providers and consumers. To keep the DRM system running in order, risk management should be adopted, which identi¯es and assesses the DRM system's security level. Now, the legitimate sharing of copyrighted digital content is still an open issue, which faces severe risks of propertied assets circumvention and copyright infringe-ments. In this paper, we try to highlight a multi-disciplinary method for all-around examinations on risks to digital assets in the contents sharing scenario. The method is a qualitative and quantitative fuzzy risk assessment, which is used for estimating a novel concept called Risk-Controlled Utility (RCU) in DRM. Then, we emphasize on an application case of the emerging trusted computing policy, and analyze the in°uences of di®erent content sharing modes. Finally, we address a business model with some simulation results. The comparison with other methods shows that the fusion of qualitative and quantitative styles can not only evaluate the RCU with uncertain risk events e®ectively, but also provide accurate assessment data for the security policies of DRM.

A legitimate contents sharing is an essential functionality of DRM (Digital Rights Management)-enabling contents industry and its value chain extension. In order to effectively choose and deploy some typical security policies in a contents sharing scenario, we introduced game theory to analysis the mutual influence of adoptions of trusted computing enabling enhanced security policies on benefits of two stakeholders, which are DRM Providers and contents Sharer who is a category of consumers. A dynamic and mixed game and its algorithm were proposed, where Sharer's strategies were whether to employ the trusted computing enabling devices and related components or not, as well as Providers' strategies included entirely general security, entirely enhanced security and dynamic security policies. We concluded from both game-theoretic analyses and Swarm simulation experiments that the number of acquired sharable digital rights and security cost have a direct effect on Sharer's choices of the enhanced security policy, and also their different basic sharing modes including partial, modest and extensive sharing, further influence the choice of Providers. Besides, with respect to the mixed sharing mode far more similar to a real contents sharing scenario, Dynamic security strategy is superior to the entirely enhanced security in the context of limited sharable rights and higher security costs, but with the acquisition of much more rights and the decrease of enhanced security overhead, the latter strategy would be optimal and stable as a Nash Equilibrium for stakeholders, in combination with the exploitation of effective business models of contents industry.

A successful transaction of digital contents is primar-ily dependent on security policies, trust relationships and benefit equilibriums among various participants in a DRM (Digital Rights Management)-enabling contents value chain ecosystem. We first analyzed basic value chain architectures in existence, together with some fundamen-tal security and trust requirements. And then, a state-of-the-art anatomy of the security and trust related to DRM was presented from different stakeholder' perspectives. Next, some challenges for multi-party mutual trust, not just inclined to any of participants, were proposed based on the holistic consideration of the digital contents/rights protection and the benefits balance. Finally, a conclusion was drawn that the rights-benefits-centric DRM ecosys-tem and the resulting trust relationship are crucial for the survivability of the contents industry.

Nowadays open and distributed Computer Supported Cooperative Work (CSCW) systems are faced with security challenges due to large numbers of cooperative users, and a mass of valued data resources need to be protected against unauthorized usage, disseminations and share. To this end, role-based collaboration framework and access control approaches have been a focus in recent years, but there lack of a holistic and comprehensive model and visual modeling. We proposed and formalized a CSCW-enabling access control model integrating generic centralized authorization and distributed authority delegation, called IACM (Integrated Access Control Model) for CSCW, based on the cooperative roles and their owned activities. And then, the visual modeling was represented with static and dynamic characteristics, with a goal to narrow the gap of the formalized model and application level. Finally, an application in the collaboration system for equipments manufacture designing was implemented to improve security of the role-based centralized authorization management by using the authorization constraint rules, and to enhance the collaborative capability based on the user-side delegation mechanism, effectively guaranteeing CSCW system security and authorization management efficiency.

Digital Rights Management ecosystem is composed of various participants, which adopt different security policies to meet their own security requirements, with a goal to achieve individual optimal benefits. However, from the perspective of the whole DRM-enabling contents industry, a simple adoption of several increasingly enhanced security policies does not necessarily implement an optimal benefit balance among participants. A game-theoretic analysis of adoptions of security policies was emphasized based on a proposed General DRM value chain ecosystem without the loss of generality. First, we formalized security policies and fundamental properties that include internal relativity and external one, together with multiparty game on adoptions of security policies. Also, a cooperative game among digital Contents Provider, Rights/Service Provider and digital Devices Provider, as well as a non-cooperative game between Providers and Consumers were presented. Final, a stable core allocation of benefits and Nash Equilibriums were found out, respectively. It is clearly concluded that the cooperative game has important super-addivitity and convexity, thus simultaneous adoptions of security policies with external relativity being helpful to achieve Pareto Optimality by using a pre-established cooperative relation; and that Pareto Optimality also exists between Providers and Consumer with the increase of users’ purchase transactions when both have a repeated game.

In recent decade, DRM (Digital Rights Management) has focused on security techniques for solving the issues as the malicious copy, free dissemination and unrestricted abuse of digital contents or assets. Whereas some increasingly enhanced security policies, which were implemented at contents provider-side or user-side, have not brought about optimal utilities for participants in the contents value chain. An analytic hierarchy structure and its algorithm on the assessment on utility factors’ weights for DRM security policies were proposed based on Fuzzy Analytic Hierarchy Process, and then Swarm simulation experiments were further made on the adoptions of typical security policies in combination with the gained weight values. The simulation results show the proposed approach to fuzzy assessments effectively implements rational and optimal decision-making on security policies combinations.

针对现有的远程证明模型中存在的终端平台基本配置细节与安全属性特征等隐私的保护问题，提出了一种具有委托模式的支持验证代理方的远程证明模型（AP2RA）及其安全协议引入可信第3方接受验证方的委托，实施终端软硬件的完整性和安全性证明，并可信地报告平台当前状态的布尔值，改进了基于验证双方的远程证明模式，有效地保护了被验证方的平台隐私与已有的方案相比，该方案能够抵抗被验证方消息重放攻击和共谋攻击，以及追踪对验证代理方（APP）发起攻击的终端平台，适用于可信网络中的资源分发与信息共享等环境。

从不同等级安全与效用分析的新角度，提出了基于模糊层次分析法的DRM安全策略效用评估及其博弈论选取。通过构建安全策略的层次分析结构，采用模糊判断一致矩阵，分析可选安全组件与服务在安全策略中的权重关系，并将所得权重用于计算DRM安全策略组合的实际效用以及进而实现博弈论选取，得出多方安全效用的Nash均衡，即最优均衡安全策略组合及其存在条件。一组典型安全策略的实例分析表明，博弈结果存在2组不同的安全策略组合，内容与服务提供商可根据数字内容购买用户数及平均购买量等应用情形来有效部署DRM系统，从而获得数字版权保护与各方实际收益的均衡。