| Summary: | Identity is a crucial property of Internet of Things (IoT) devices. Due to rapid growth and high numbers of similar devices, reliable identification of those devices is a problem. The origin and history of an IoT device is especially important in security relevant environments.
Our research addresses this issue by proposing an approach based on blockchain and decentralized identifiers (DID). It is inspired by the concepts of self-sovereign identity (SSI) and bootstrapping of remote secure key infrastructures (BRSKI). Devices are equipped by the manufacturer with an identity stored in a trusted execution environment (TEE) and secured by a blockchain. This identity can be used to trace back the origin of the device. During the bootstrapping process on the customer side, the identity registration of the device is updated in the blockchain. This process is performed by a so-called registrar. Smart contracts prevent unsolicited transfer of ownership and track the history of the device. Besides proof of origin and device security our concept can be used for device inventory and firmware upgrade.
A prototype implementation was realized to validate the concept. All six use cases have been implemented and tested using an Ethereum blockchain infrastructure. JSON Web Tokens (JWT) have been used as signed artefacts to transfer information between the stakeholders. This enables an asynchronous communication needed for example in an environment with no direct internet access. Such an infrastructure can be provided by an independent association and can be used by all manufacturers. Depending on the environment, a registration of devices can be optional or mandatory.
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