CAREER: Evidence in Federated Distributed Systems

联邦分布式系统（即由多个不同的组织或个人联合操作的系统）的趋势正在增加。在这样一个系统中，参与者的利益往往是高度多样化和/或相互冲突的；例如，参与者可能是商业竞争对手或总部设在敌对国家。因此，联邦系统天生就容易受到内部攻击：参与者可以试图破坏系统，利用它为自己谋取利益，或者攻击其他参与者。然而，联邦系统中的参与者通常也在“离线世界”中连接，例如，通过社交网络或业务关系。这种背景可以通过众所周知的、经过时间考验的技术（如问责制和透明度）来处理不当行为。例如，如果一个参与者可以发现并证明另一个参与者有不当行为，她可以起诉该参与者违反合同。本研究的目标是开发一种支持这种方法的关键技术，即一种可靠和通用的方法来生成和验证联邦系统中不当行为的证据。该项目(i)研究创建证据的基本权衡、要求和固有成本；（ii）开发新的算法，有效地支持不同种类的证据；（iii）在实际系统的背景下评估这些算法。该项目与宾夕法尼亚大学市场与社会系统工程新开设的本科课程相结合。它将生产并免费分发可用于保护联邦系统免受攻击和恶意内部人员攻击的软件。

There is an increasing trend towards federated distributed systems, i.e., systems that are operated jointly by multiple different organizations or individuals. The interests of the participants in such a system are often highly diverse and/or in conflict with one another; for example, participants may be business competitors or based in hostile nations. Thus, federated systems are inherently vulnerable to insider attacks: the participants can try to subvert the system, exploit it for their own benefit, or attack other participants.However, the participants in a federated system are typically connected in the 'offline world' as well, e.g., through social networks or business relationships. This context can be leveraged to handle misbehavior through well-known, time-tested techniques like accountability and transparency. For example, if one participant can detect and prove that another participant has misbehaved, she can sue that participant for breach of contract.The goal of this research is to develop a key technology for enabling this approach, namely a reliable and general way to generate and verify evidence of misbehavior in federated systems. The project (i) studies the fundamental tradeoffs, requirements, and inherent costs of creating evidence; (ii) develops new algorithms for efficiently supporting different kinds of evidence; and (iii) evaluates these algorithms in the context of practical systems.The project is integrated with Penn's new undergraduate program in Market and Social Systems Engineering. It will produce and freely distribute software that can be used to defend federated systems against attacks and malicious insiders.