Structured Encryption for Indirect Addressing

The Structured Encryption (StE) framework can be used to capture the encryption and querying of complex data structures on an honest-but-curious server. In this work, we introduce a new type of StE called indirectly addressed multimap encryption (IA-MME). We propose two IA-MME schemes: the layered multimaps approach" which extends and generalizes the existing "multimap chaining" approach, and a novel technique called the single multimap approach which has comparable efficiency and strictly better security. We demonstrate that our formalisms simplify and modularize StE solutions for real-world use cases in searchable encryption and SQL databases, and provide simulations demonstrating that our IA-MME constructions lead to tangible efficiency and security gains on realistic data. As a part of our techniques, we identify and correct a technical error in prior constructions — providing greater insight into issues that can arise when composing StE schemes.