Cloud federation is an emergent cloud-computing paradigm that allows services from different cloud systems to be aggregated in a single pool. To support secure data sharing in a cloud federation, anonymization services that obfuscate sensitive datasets under differential privacy have been recently proposed. However, by outsourcing data protection to the cloud, data owners lose control over their data, raising privacy concerns. This is even more compelling in multi-query scenarios in which maintaining privacy amounts to controlling the allocation of the so-called privacy budget. In this paper, we propose a blockchain-based approach that enables data owners to control the anonymization process and that enhances the security of the services. Our approach relies on blockchain to validate the usage of the privacy budget and adaptively change its allocation through smart contracts, depending on the privacy requirements provided by data owners. Prototype implementation with the Hyperledger permissioned blockchain validates our approach with respect to privacy guarantee and practicality. Cloud federation builds up interconnectivity and cooperation among already-deployed clouds, enabling organizations to achieve various business goals, such as controlled sharing of data and services and optimization of computing resource usage. To support secure sharing of federated data, anonymization services have been proposed as a building component of federation-as-a-service (FaaS), 3, 4 a recent cloud federation solution. This component implements differential privacy to obfuscate the result of statistical queries towards sensitive datasets, 5 enabling its privacy-preserving sharing. Offering this service in the context of a cloud federation has benefits-access to multiple data sources and different service providers-but raises significant challenges for privacy management, such as sensitive datasets from
Yang et al. REF presents a blockchain-based approach that enables O to control the anonymization process, and enhances the security of the services, by validating the usage of privacy budget and adaptively changing its allocation via smart contracts according to the privacy requirements of O. Table 8 summaries the differences between our proposal model and existing work.
Differentially Private Data Sharing in a Cloud Federation with Blockchain
IEEE Cloud Computing
IEEE Cloud Computing
Computer Science