What is a Decentralized Identifier

A Decentralized Identifier (DID) serves as a unique identifier in the digital field, offering verifiable ownership without reliance on centralized authorities. DIDs are integral to Self-Sovereign Identity (SSI), which lets people to manage their own digital identities.

Visualize a DID as a personal, self-owned phone number, diverging from the traditional system where telecom companies assign numbers. It acts as a permanent and portable address in the digital sector.

The Problem with Traditional Identifiers

In the Web2 environment, control over digital identities remains fragmented and largely in the hands of corporations. Consider the following examples:

Identifier Type	Controlled By
Email Address	Major tech companies
Social Media Handle	Social media platforms

These platforms can revoke access to your identifiers, impose censorship, or exploit your data. As a result, users lack true ownership over their online identities.

How DIDs Work

A DID appears as a simple text string, such as did:example:123456789abcdefghi. This structure comprises three components:

1. The Scheme: did: indicates the identifier as a DID.
2. The DID Method: example: denotes the specific blockchain or Distributed Ledger Technology (DLT) hosting the DID's records. Various methods exist, including did:ethr: for Ethereum and did:btcr: for Bitcoin.
3. The Method-Specific Identifier: 123456789abcdefghi represents a unique string generated by the DID method, often derived from a cryptographic public key.

The DID Document: The "Business Card"

A DID functions as an address until it connects to a DID Document. This JSON file linked to the DID contains essential information:

• Cryptographic Public Keys: Used to validate signatures from the DID's controller.
• Authentication Methods: Details on how the DID's controller authenticates themselves, such as signing messages with specific keys.
• Service Endpoints: URLs for services associated with the DID, which may include data storage locations or communication methods with the DID's owner.

When a user creates a DID and its corresponding DID Document, they register it on a chosen blockchain. The user maintains control over the private key linked to the public keys in the DID Document, ensuring that only they can modify the document.

Why DIDs Matter for Web3

DIDs lay the groundwork for a more user-centric and private internet.

• User Control: Individuals possess their identifiers, eliminating the risk of loss or removal.
• Portability: Users can apply the same DID across various applications and services, allowing for a consistent reputation and history.
• Privacy: DIDs maintain pseudonymity unless users opt to associate them with real-world identities.
• Enabling Verifiable Credentials: DIDs form the basis for Verifiable Credentials. For example, a university can issue a digital diploma to a DID, enabling the holder to prove their qualifications to employers without necessitating direct contact with the institution.

Decentralized Identifiers represent a straightforward yet impactful concept. They shift identity control from centralized platforms to individuals, building a more secure, private, and interoperable digital environment.