Efficient and Scalable Query Authentication for Cloud-Based Storage Systems with Multiple Data Sources

Storage services are among the primary cloud computing offerings, providing advantages of scale, cost and availability to its customers. However, studies and past experiences show that large-scale storage service can be unreliable, and vulnerable to various internal and external threats that cause loss and/or corruption of customer data. In this work, we present a query authentication scheme for cloud-based storage system where the data is populated by multiple sources and retrieved by the clients. The system allows clients to verify the authenticity and integrity of the retrieved data in a scalable and efficient way, without requiring implicit trust on the storage service provider. The proposed mechanism is based on our recently proposed multi-trapdoor hash functions, using its properties to achieve near constant communication and computation overhead for authenticating query responses, regardless of the data size, or the number of sources. We develop a discrete log-based instantiation of the scheme and evaluate its security and performance. Our security analysis shows that forging the individual or aggregate authentication tags is infeasible under the discrete log assumption. Our performance evaluation demonstrates that the proposed scheme achieves superior efficiency and scalability compared to existing query authentication schemes offering support for multiple sources.