Dynamic proofs of retrievability with low server storage
This addresses the need for secure and efficient remote data storage verification for cloud users, offering a novel approach with practical deployment benefits.
The paper tackles the problem of efficiently verifying remote data integrity in dynamic storage systems, proposing new dynamic Proofs of Retrievability protocols that trade server storage for computation, with a lower bound proof showing this tradeoff is inherent, and demonstrates scalability by auditing a 1TB file in under 5 minutes for less than $0.08.
Proofs of Retrievability (PoRs) are protocols which allow a client to store data remotely and to efficiently ensure, via audits, that the entirety of that data is still intact. A dynamic PoR system also supports efficient retrieval and update of any small portion of the data. We propose new, simple protocols for dynamic PoR that are designed for practical efficiency, trading decreased persistent storage for increased server computation, and show in fact that this tradeoff is inherent via a lower bound proof of time-space for any PoR scheme. Notably, ours is the first dynamic PoR which does not require any special encoding of the data stored on the server, meaning it can be trivially composed with any database service or with existing techniques for encryption or redundancy. Our implementation and deployment on Google Cloud Platform demonstrates our solution is scalable: for example, auditing a 1TB file takes just less than 5 minutes and costs less than $0.08 USD. We also present several further enhancements, reducing the amount of client storage, or the communication bandwidth, or allowing public verifiability, wherein any untrusted third party may conduct an audit.