Traditional electricity meters are replaced by Smart Meters in customers' households. Smart Meters collects fine-grained utility consumption profiles from customers, which in turn enables the introduction of dynamic, time-of-use tariffs. However, the fine-grained usage data that is compiled in this process also allows to infer the inhabitant's personal schedules and habits. We propose a privacy-preserving protocol that enables billing with time-of-use tariffs without disclosing the actual consumption profile to the supplier. Our approach relies on a zero-knowledge proof based on Pedersen Commitments performed by a plug-in privacy component that is put into the communication link between Smart Meter and supplier's back-end system. We require no changes to the Smart Meter hardware and only small changes to the software of Smart Meter and back-end system. In this paper we describe the functional and privacy requirements, the specification and security proof of our solution and give a performance evaluation of a prototypical implementation.
Electricity suppliers have started replacing traditional electricity meters with so-called smart meters, which can transmit current power consumption levels to the supplier within short intervals. Though this is advantageous for the electricity suppliers' planning purposes, and also allows the customers a more detailed look at their usage behavior, it means a considerable risk for privacy. The detailed information can be used to judge whether persons are in the household, when they come home, which electric devices they use (e.g. when they watch TV), and so forth. In this work, we introduce the "smart metering privacy model" for measuring the degree of privacy that a smart metering application can provide. Moreover, we present two design solutions both with and without involvement of trusted third parties. We show that the solution with trusted party can provide "perfect privacy" under certain conditions.