Smart meter aggregation via secret-sharing

We design and prototype protocols for processing smart-meter readings while preserving user privacy. We provide support for computing non-linear functions on encrypted readings, implemented by adapting to our setting efficient secret-sharing-based secure multi-party computation techniques. Meter readings are jointly processed by a (public) storage service and a few independent authorities, each owning an additive share of the readings. For non-linear processing, these parties consume pre-shared materials, produced by an off-line trusted third party. This party never processes private readings; it may be implemented using trusted hardware or somewhat homomorphic encryption. The protocol involves minimal, off-line support from the meters---a few keyed hash computations and no communication overhead.