IO-DSSE: Scaling Dynamic Searchable Encryption to Millions of Indexes By Improving Locality

Free cloud-based services are powerful candidates for deploying ubiquitous encryption for messaging. In the case of email and increasingly chat, users expect the ability to store and search their messages persistently. Using data from one of the top three mail providers, we confirm that for a searchable encryption scheme to scale to millions of users, it should be highly IO-efficient (locality), and handle a very dynamic message corpi. We observe that existing solutions fail to achieve both properties simultaneously. We then design, build, and evaluate a provably secure Dynamic Searchable Symmetric Encryption (DSSE) scheme with significant reduction in IO cost compared to preceding works when used for email or other highly dynamic message corpi.