The Internet of Things (IoT) connects a large number of devices, with their security relying on reliable digital identities. Traditional approaches, such as static identifiers, pre-shared keys (PSK), public key infrastructure (PKI) and tokens, face limitations in terms of security, scalability, and dependence on centralized authorities. This raises questions about identity ownership and increases the risk of a single point of failure.
This thesis analyzes existing device identification and authentication methods, as well as their extensions, such as lightweight PKI solutions, automatic enrollment, and hardware security elements. The findings show that these approaches do not resolve the fundamental issue of identity ownership sovereignty.
A practical prototype was developed based on the concept of decentralized and self-sovereign identities (SSI). Devices generate their own decentralized identifiers (DID), store the corresponding DID documents in the IPFS network, and anchor their content identifiers (CID) on the Polygon blockchain. Based on this, authentication is performed with verifiable credentials (VC). Measurements showed that, despite the limitations of resource-constrained devices, identity files remain small enough for local storage, while cryptographic key generation in such cases needs to be carried out externally in secure hardware elements. It was also shown that off-chain authentication is significantly faster and more cost-efficient than on-chain approaches, where each authentication requires a new transaction.
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