Blockchain in IoT and Beyond: Case Studies …

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Fig. 3 The Zero Knowledge

Proof (ZKP)

3.2.2

Decentralized Identity

Our digital identity is linked with the application, service, and device we are

involved with DIDs [26]. This makes the identity vulnerable to be misused because

it is managed by some centralized authority or third-party service provider. Each

individual has a privilege to a personality that they own and control.

Decentralized Identity fosters a greater level of control, trust, and security for apps,

IoT devices [27] as well as service providers. Privacy can be guaranteed by means

of pseudonymization [28]. So, instead of storing actual private data and information,

the things that are stored in the blockchain are:

• Public Decentralized Identifiers (Public DIDs) and associated DID Descriptor

Objects (DDOs) with verification keys and endpoints.

• Schemas

• Credential definitions

• Revocation registries

• Proofs of consent for data sharing

The concept of DIDs is credited to have been inspired from that of Uniform

Resource Names (URN) [29] and in specific from that of UUIDs. UUIDs are unique

identifiers that can be created locally. These are 128-bit values that can be used to

uniquely identify an entity in a system. The format of a URN has been specified by

RFC 8141 and can be commonly classified as: