What is a Decentralized Identifier (DID)?

A Decentralized Identifier (DID) is a unique digital identity managed by an individual or organization, independent of centralized registries or identity providers. Unlike traditional usernames or IDs controlled by external entities (like companies or governments), DIDs allow users to own, control, and manage their own digital identities securely.

Key characteristics of Decentralized Identifiers include:

• Decentralization: No central authority or single point of failure.
• Persistent and Resilient: Remains stable over time, independent of any specific service or platform.
• Cryptographically Verifiable: Enables secure verification of identity ownership using cryptographic methods.
• Privacy Preserving: Users selectively disclose personal attributes, reducing unnecessary data exposure.

DIDs are fundamental in systems like Self-Sovereign Identity (SSI), enabling secure authentication, credential sharing, and trust establishment without centralized databases or intermediaries.

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Decentralized Identifiers emerged as a response to growing concerns around privacy, data breaches, and centralized identity management. Traditional digital identity systems store sensitive user data in central databases, making them vulnerable to hacking, misuse, or loss of control. By contrast, DIDs provide a more secure, user-controlled alternative.

Each DID is typically represented as a string, similar to a URL. It points to a decentralized DID Document containing:

• Public Keys: For cryptographic authentication and verification.
• Service Endpoints: Locations where interactions or identity verification can occur.
• Authentication Methods: Information on how users prove ownership of the DID.

This DID Document is stored on decentralized networks or blockchains, ensuring no single authority can revoke or alter identity information without user consent.

Multiple DID methods exist, each utilizing different decentralized networks:

• did:web – Managed via web domains, offering simplicity but moderate decentralization.
• did:key – Based purely on cryptographic keys, with high decentralization and simplicity.
• did:ion – Built on Bitcoin, providing strong decentralization and long-term persistence.
• did:ethr – Utilizing Ethereum blockchain, widely adopted for secure identity management.

The W3C DID standard ensures interoperability, defining core DID concepts, formats, and mechanisms for resolving and verifying DIDs across different platforms.

Decentralized Identifiers are ideal for secure and private digital identity management in various scenarios, including:

• User Authentication: Securely accessing applications without usernames/passwords.
• Credential Sharing: Verifiable Credentials (VCs) allow selective, private sharing of identity attributes like age or qualifications.
• Supply Chain and IoT: Securely identifying and authenticating physical assets and devices, improving supply chain security.
• Healthcare: Safely managing sensitive medical records with full user control and minimal third-party exposure.

Decentralized Identifiers complement modern authentication methods like passkeys (FIDO2/WebAuthn) by offering secure, decentralized storage and management of digital identities. Combined, they create robust authentication solutions that enhance user control, reduce phishing risks, and strengthen privacy.

A DID is a cryptographically secured, user-controlled digital identity that operates independently from centralized identity providers or databases.

DIDs allow users to manage their own identity data, selectively disclosing attributes only as needed, reducing reliance on third-party data storage.

DIDs and their associated DID Documents are typically stored on decentralized networks or blockchains, ensuring resilience and decentralization.

The W3C DID standard specifies formats, methods, and protocols, ensuring interoperability across various DID implementations and decentralized networks.

Users maintain full control over their DIDs, including revocation or updates, without requiring permission from any external authority or central registry.