Decentralized Identifier (DID)

A DID follows the URI syntax did:method:identifier (for example did:web:example.com or did:key:z6Mk...) and resolves to a DID Document in JSON or JSON-LD that holds the public keys, authentication methods and service endpoints tied to it. The DID Method defines how the identifier is created, resolved, updated and deactivated on a given substrate, whether a blockchain, a web domain or the key itself. The W3C registry lists more than one hundred methods.

It moves identity control to the user. Whoever holds the private key proves control of the DID without a federated login or an issuer that can revoke access. Verifiable credentials are signed and verified on this base, and in tokenization it enables reusable KYC and permissioned access to assets without repeating verification on each platform. It is the foundational piece of self-sovereign identity.

In practice, did:web relies on DNS and HTTPS with no on-chain cost and is widely used by institutions, did:ethr runs on Ethereum and did:key is self-contained. Microsoft deployed the did:ion method on Bitcoin. The standard reached DID Core v1.0 by W3C Director decision in June 2022, and version 1.1 advanced to Candidate Recommendation in March 2026, with implementations invited. In the European Union, eIDAS 2.0 and its EUDI Wallet bring these principles into the single-market framework.