Decentralized Identifiers (DIDs)

Introduction

Decentralized Identifiers (DIDs) are a type of identifier that enables a verifiable, decentralized digital identity. These identifiers are designed to be fully under the control of the DID subject, independent from any centralized registry, identity provider, or certificate authority. DIDs are URLs that relate a DID subject to means for trustable interactions with that subject. DIDs resolve to DID Documents which are simple documents describing how to use that specific DID. Each DID Document may express cryptographic material, verification methods, or service endpoints, which provide a set of mechanisms enabling a DID controller to prove control of the DID. Service endpoints enable trusted interactions with the DID subject.

A computer screen showing a generated Decentralized Identifier (DID).

History and Context

The concept of Decentralized Identifiers (DIDs) emerged from the work of the Decentralized Identity Foundation and the World Wide Web Consortium's (W3C) Credentials Community Group. The idea was to create a new kind of identifier that could be generated, resolved, and disposed of by the entity it refers to, without the need for a centralized authority or registry. This was in response to the increasing need for privacy, security, and user control in digital identity systems, which traditional identifiers could not adequately provide.

Structure of a DID

A Decentralized Identifier (DID) is composed of three parts: the scheme, the method, and the method-specific identifier. The scheme is always "did", indicating that the identifier is a DID. The method is a short name that indicates the DID Method used to generate, resolve, and manage the DID. The method-specific identifier is a string generated by the DID Method. The structure of this string is defined by the specific DID Method, and it may include additional components, such as a version number or a path.

DID Methods

DID Methods are specifications that define how a DID is created, resolved, updated, and deactivated. Each DID Method is defined in its own DID Method specification, which is typically published as a separate document. There are currently over 40 registered DID Methods, including "did:btcr" for Bitcoin, "did:ethr" for Ethereum, and "did:sov" for the Sovrin network. Each DID Method has its own strengths and weaknesses, and is designed for specific use cases and environments.

DID Documents

A DID Document is a data structure that contains information about a DID, including public keys, authentication protocols, and service endpoints. The DID Document is essential for verifying the identity of the DID subject and for interacting with the DID subject. The structure and content of a DID Document is defined by the DID specification, but it may also be influenced by the specific DID Method.

Use Cases

Decentralized Identifiers (DIDs) have a wide range of potential use cases, including user-centric identity, secure messaging, verifiable credentials, and decentralized autonomous organizations (DAOs). In all these use cases, DIDs provide a way to establish trust without the need for a centralized authority or registry.

Challenges and Limitations

While DIDs have many potential benefits, they also face several challenges and limitations. These include technical challenges related to scalability and interoperability, as well as legal and regulatory challenges related to privacy and data protection. Furthermore, the adoption of DIDs depends on the development of supporting infrastructure and ecosystems, which is still in its early stages.

Future Developments

The future of Decentralized Identifiers (DIDs) is likely to be influenced by several factors, including technological advancements, market trends, and regulatory developments. Potential future developments include the integration of DIDs with other technologies, such as blockchain and artificial intelligence, the development of new DID Methods and use cases, and the establishment of legal and regulatory frameworks for DIDs.