This book investigates decentralized trust-based privacy-preserving solutions in smart cities. The authors first present an overview of smart cities and privacy challenges and discuss the benefits of adopting decentralized trust models in achieving privacy preservation. The authors then give a comprehensive review of fundamental decentralized techniques and privacy-preserving cryptographic techniques. The next four chapters each detail a decentralized trust-based scheme, focusing respectively on privacy-preserving identity management, cross-domain authentication, data analytics, and data search, in specific use cases. Finally, the book explores open issues and outlines future research directions in the field of decentralized privacy preservation. Discusses benefits and challenges of applying decentralized trusts in smart cities Provides scheme designs and security analysis for use cases in smart cities, offering insights into applications Includes cryptographic knowledge accompanied by practical algorithm and protocol implementations.