Decentralized identity (DID) is a transformative paradigm that leverages blockchain, decentralized identifiers and verifiable credentials (VCs) to enable self-sovereign and decentralized identity management with myriad application areas. However, existing DID implementations are confronted with two key challenges: insufficient decentralization and vulnerability to mobile adversary attacks. First, they paradoxically introduce central identity resolvers, intermediaries or static committees to manage critical identity services, key management or credential issuance, which violates the decentralized controlling aim against a single point of failure. Second, these systems are vulnerable to mobile adversaries who can gradually compromise multiple nodes or committee members over a long period, eventually seizing control of the system. In this paper, we propose DP-DID, the first dynamic and proactive decentralized identity system specifically designed to resist mobile adversary attacks in dynamic committee settings. To eliminate centralized authorities, DP-DID leverages blockchain, dynamic committees and BLS1signatures, which achieves decentralization. In addition, we design a dynamic and batch proactive secret sharing (DBPSS) scheme for DP-DID to ensure proactive security against mobile adversary attacks. This is achieved by allowing at mostt(threshold) committees to be corrupted per period, with the set of corrupted committees changing dynamically even if all players are eventually compromised. By incorporating DBPSS, DP-DID achieves efficient key management for multiple users in dynamic settings, enhancing overall system scalability. Through rigorous analysis, DP-DID is proven to be forward secure and secure against mobile adversary attacks under a widely adopted malicious model. Extensive experiments show that DP-DID has efficient performance, and our DBPSS scheme outperforms FaB-DPSS by over 11.67× in key handover efficiency.

In SDN, to enable resilience each switch can be mapped to multiple controllers (e.g., primary, secondary) and distribute the control traffic among them. The SDN controllers for each switch need to be chosen in a manner that does not compromise on network response time, while taking controller reliability into consideration. Given the switch-primary controller mapping, the objective of our work is to find an optimal switch-secondary controller mapping and control traffic distribution such that the reliability of mapped controllers is maximized. We mathematically model controller reliability, formulate and solve the optimization problem with the above objective. We implement a switch-controller mapping approach in SDN, wherein we map each switch to two active controllers and distribute the flow-setup requests (control traffic) between them. We implement our approach using Floodlight controllers and Mininet, and show that it improves reliability of mapping and achieves better recovery time upon controller failure by up to 27.3% as compared to the traditional master-slave setup.