PrivacyGuard: Enforcing Private Data Usage Control with Blockchain and Attested Off-chain Contract Execution
This addresses privacy concerns for individual data owners in big data applications, but it is incremental as it combines existing technologies like blockchain and TEEs.
The authors tackled the problem of controlling private data usage by proposing PrivacyGuard, a system that uses blockchain smart contracts and trusted execution environments to enforce data usage policies and maintain immutable records, achieving privacy goals and supporting analytics for many data owners.
The abundance and rich varieties of data are enabling many transformative applications of big data analytics that have profound societal impacts. However, there are also increasing concerns regarding the improper use of individual data owner's private data. In this paper, we propose PrivacyGuard, a system that leverages blockchain smart contract and trusted execution environment (TEE) to enable individual's control over the access and usage of their private data. Smart contracts are used to specify data usage policy, i.e., who can use what data under which conditions and what analytics to perform, while the distributed blockchain ledger is used to keep an irreversible and non-repudiable data usage record. To address the efficiency problem of on-chain contract execution and to prevent exposing private data on the publicly viewable blockchain, PrivacyGuard incorporates a novel TEE-based off-chain contract execution engine along with a protocol to securely commit the execution result onto blockchain. We have built and deployed a prototype of PrivacyGuard with Ethereum and Intel SGX. Our experiment result demonstrates that PrivacyGuard fulfills the promised privacy goal and supports analytics on data from a considerable number of data owners.