CapChain: A Privacy Preserving Access Control Framework Based on Blockchain for Pervasive Environments

Devices to support pervasive computing and the Internet of Things (IoT) are becoming present in almost every aspect of our lives. Due to their limited power and computation, these devices often need to rely on some more powerful outsourced cloud services, which raises a security and privacy concern as IoT data is often sensitive. On the other hand, blockchain technology has recently gained much attention due to its decentralized, trustless and immutable design. We propose CapChain - an access control framework based on blockchain that allows users to share and delegate their access rights easily to IoT devices in public but still maintain privacy. To protect privacy, we adapt multiple techniques from anonymous crypto-currency blockchain systems to hide sensitive information, including users' identities and related information about the capabilities. We also build a testbed as a proof of concept.