What it takes to boost Internet of Things privacy beyond encryption with unobservable communication: a survey and lessons learned from the first implementation of DC-net

Privacy requires more than just encryption of data before and during transmission. Privacy would actually demand hiding the sheer fact that communication takes place. This requires to protect meta-data from observation. We motivate the need for strong privacy protection in a smart home use case by highlighting the privacy issues that cannot be solved by confidentiality mechanisms like encryption alone. Our solution is a implementation of DC-net on Re-Mote sensor nodes running Contiki OS. From this, we conclude that the computational and network overheads imposed by these techniques do not make them impractical to use in the IoT. To the best knowledge of the authors, this is the first implementation of DC-net on sensors. Alongside, we provide a survey of the required strong cryptographic security mechanisms, like encryption of communication, to be in place. We describe how the current existing techniques can be facilitated to achieve unobservable communication for the IoT. This includes mechanisms for encrypted IoT communication like DTLS or message authentication like ECDSA signatures on IoT devices. For readers unfamiliar with the concepts of MIXing and DC-net, we explain and analyse how those techniques, formerly used to provide private communication in the Internet, can be applied to the IoT. We briefly survey what complementary features from the IoT architecture are helpful in providing strong protection in this particular use case. Finally, we state some recommendations hoping that following these will enable us to reduce the privacy invasiveness of the IoT on all levels. We think that this will be indispensable if IoT devices shall become a part of our daily lives without rendering us into an Orwellian society.