The iTrust system is a decentralized and distributed publication, search and retrieval system that makes it difficult to censor or filter information accessed over the Internet. iTrust employs a completely distributed membership algorithm, and a detection and defensive adaptation algorithm that protects against malicious nodes in the membership. These algorithms depend on information that cannot be observed or measured directly, the current size of the membership and the current proportion of malicious nodes in the membership. They use statistical estimation to approximate these network environment parameters, and then they dynamically adapt accordingly. These algorithms provide accurate and timely management of the iTrust system in the presence of membership churn and malicious nodes.