Safavi-Naeini, Reyhaneh AlsadatRahman, Saoreen2022-01-312022-01-312022-01-27Rahman, S. (2022). Resource Sharing using Permissioned Blockchain: The Case of Smart Neighborhood (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.http://hdl.handle.net/1880/114372In a resource sharing system users can offer goods and services with specified conditions which if satisfied, the access will be granted. In conventional resource sharing systems, users' interactions are mediated by a trusted authority (TA). As a result, TA becomes the single point of trust and has access to users' data. In addition, TA requires significant processing and management capabilities, and the ability to handle many requests simultaneously which may make it a single point of failure under various denial of service attacks. Motivated by the advantages of emerging blockchain technology, a decentralized resource sharing system was proposed which uses a permissioned blockchain based resource sharing system for allowing users to share their digital items and credentials with specified attributed-based access policies, and are enforced through a set of smart contracts. The system eliminates the need for a trusted intermediary and overcome the shortcomings associated to it. However, such a system allows users' accesses to be tracked and has limited availability since access to a resource requires the resource's owner to be online. Our proposed architecture offers the same required functionality while ensuring user privacy and access automation, and eliminating the requirement for the resource owner to be online. We use two cryptographic primitives, Ciphertext Policy Attribute-Based Encryption (CPABE) and ring signatures, and develop smart contracts that allow specification of the user-defined policies. We analyze security and privacy of this system, provide the description of smart contracts and construct protocols for the proposed system. We present a case study and conduct performance evaluation of cryptographic primitives and blockchain operations, and show that the overhead for cryptographic operations is adding up to two seconds to the user interaction time, and the gas cost is below 2600000. We design and implement a web application, smart neighborhood, which represents the proposed system by providing user interface (UI) for its user. Although our work is motivated by sharing digital items in distributed resource sharing system, our design and implementation are general and can be employed for wider applications for privacy-preserving sharing of digital items.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Privacy-preserving resource sharingBlockchainSmart contractAttribute-based access controlAttribute-based encryptionAnonymous authenticationSmart neighborhoodInformation ScienceEducation--Technologymaster thesishttp://dx.doi.org/10.11575/PRISM/39577