A DID Document is a key component of a decentralized identity system. It describes how to interact securely with the subject identified by a DID (Decentralized Identifier).

Every DID resolves to a corresponding DID Document, which contains the public information necessary to establish trusted, secure communication with the DID’s owner.

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What’s Inside a DID Document?

A DID Document is typically a JSON or JSON-LD file and includes:

• Public Keys: Used to verify digital signatures and encrypt data.
• Authentication Methods: Ways to prove control of the DID (e.g., via cryptographic signatures).
• Service Endpoints: URLs or other contact methods, such as messaging or credential issuance endpoints.
• Verification Relationships: Definitions of how the keys can be used (e.g., for authentication, assertion, delegation).

Example Structure

{
  "@context": "https://www.w3.org/ns/did/v1",
  "id": "did:example:123456789abcdefghi",
  "verificationMethod": [{
    "id": "did:example:123456789abcdefghi#keys-1",
    "type": "Ed25519VerificationKey2018",
    "controller": "did:example:123456789abcdefghi",
    "publicKeyBase58": "H3C2AVvLMfQ1...etc"
  }],
  "authentication": [
    "did:example:123456789abcdefghi#keys-1"
  ],
  "service": [{
    "id": "did:example:123456789abcdefghi#vcs",
    "type": "VerifiableCredentialService",
    "serviceEndpoint": "https://example.com/vc/"
  }]
}

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Why Is It Important?

The DID Document enables:

• Verification of Identity: You can cryptographically verify that the person or system claiming a DID actually controls it.
• Secure Communications: Service endpoints allow encrypted communication with the DID subject.
• Interoperability: DID Documents follow a standard format, making them readable and usable across platforms and ecosystems.

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Where Is It Stored?

Depending on the DID method, the DID Document can be:

• Stored on-chain (e.g., on a blockchain),
• Stored off-chain and referenced by the DID,
• Dynamically generated when the DID is resolved.

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Related Terms

• DID: The decentralized identifier itself.
• DID Resolver: A tool that looks up a DID and returns the corresponding DID Document.
• Verifiable Credential (VC): A signed digital credential that often links back to a DID Document for verification.