Data Staging on Untrusted Surrogates

We show how untrusted computers can be used to facilitate secure mobile data access. We discuss a novel architecture, data staging, that improves the performance of distributed file systems running on small, storage-limited pervasive computing devices. Data staging opportunis-tically prefetches files and caches them on nearby surrogate machines. Surrogates are untrusted and unmanaged: we use end-to-end encryption and secure hashes to provide privacy and authenticity of data and have designed our system so that surrogates are as reliable and easy to manage as possible. Our results show that data staging reduces average file operation latency for interactive applications running on the Compaq iPAQ hand-held by up to 54%.