A Query Language to Enhance Security and Privacy of Blockchain as a Service (BaaS)

Nasrin Sohrabi, Norrathep Rattanavipanon, Zahir Tari

Abstract: Service computing has been widely adopted in most applications. Blockchain as a Service (BaaS) is a recent offering by major service computing providers to facilitate the adoption of blockchain technology and address the implementation challenges faced by developers. This has significantly boosted blockchain use in different areas/domains such as supply chain management and healthcare. This surge in adoption has created a demand for effective data query mechanisms on blockchain platforms. However, current solutions have not adequately addressed the need to query data privately while ensuring data integrity, especially when blockchain is offered as a service. To this end, this paper proposes a query language, called \(\pi \)QLB, for blockchain systems that ensure both confidentiality of query inputs and integrity of query results. Additionally, \(\pi \)QLB enables SQL-like queries over the blockchain data by introducing relational data semantics into the existing blockchain database. \(\pi \)QLB has applied the recent cryptography primitive, namely the function secret sharing (FSS), to achieve the confidentiality property. To support integrity, we extended the traditional FSS setting in such a way that integrity of FSS results can be efficiently verified. To the best of our knowledge, \(\pi \)QLB is the first query model designed for blockchain with the support for confidentiality, integrity, and SQL-like queries.