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Controller Documents

This document explains Controller Documents (also known as Controlled Identifier Documents), a core concept in the W3C Controlled Identifier (CID) specification. Controller Documents serve as the foundation for verifiable cryptographic interactions in Vidos.

What are Controller Documents?

Section titled “What are Controller Documents?”

Controller Documents are machine-readable documents containing cryptographic material and service endpoints used to verify proofs from, and interact with, the controller of an identifier. They establish trust anchors by providing verification methods to validate authority over identifiers.

Controller Documents are closely related to DID Documents but serve as a more generalized concept that DID Documents implement.

Core Components

Section titled “Core Components”

A Controller Document consists of several key components:

Identifiers

Section titled “Identifiers”

Every Controller Document includes:

  • Subject: The entity described (the id property)
  • Controller: Entity with authority to change the document
  • Also Known As: Optional additional identifiers for the subject

Verification Methods

Section titled “Verification Methods”

Verification methods provide cryptographic material to verify proofs. Each method has a unique identifier, type (cryptographic algorithm), verification material (e.g., public key), and controller reference.

Verification Relationships

Section titled “Verification Relationships”

Verification relationships define how verification methods can be used:

Services

Section titled “Services”

Services define endpoints for interacting with the subject (e.g., credential issuers, messaging endpoints, data storage).

Controller Document Structure

Section titled “Controller Document Structure”

Controller Documents follow a structured data model with standardized properties:

{
    "@context": "https://www.w3.org/ns/cid/v1",
    "id": "https://controller.example",
    "controller": "https://controller.example",
    "verificationMethod": [
        {
            "id": "https://controller.example#key-1",
            "type": "Multikey",
            "controller": "https://controller.example",
            "publicKeyMultibase": "z6MkmM42vxfqZQsv4ehtTjFFxQ4sQKS2w6WR7emozFAn5cxu"
        }
    ],
    "authentication": ["https://controller.example#key-1"],
    "assertionMethod": ["https://controller.example#key-1"],
    "service": [
        {
            "id": "https://controller.example#messaging",
            "type": "MessagingService",
            "serviceEndpoint": "https://example.com/messages"
        }
    ]
}

How Controller Documents Function in Vidos

Section titled “How Controller Documents Function in Vidos”

Within Vidos, Controller Documents play a crucial role in verification:

The resolver service takes an identifier as input, retrieves the associated Controller Document, and provides verification methods for cryptographic validation. This establishes trust without centralized identity providers, similar to DID Resolution.

Vidos Integration

Section titled “Vidos Integration”

Controller Documents integrate with:

  • Resolver (translates identifiers to documents)
  • Verifier (validates signatures and credentials)
  • Validator (ensures conformance)
  • Authorizer (authenticates and authorizes)
  • Library services

Use Cases

Section titled “Use Cases”

Controller Documents enable identity verification (cryptographic proof without passwords), credential verification (validating signatures), secure communication (encrypted channels), service discovery (standardized interaction methods), and capability authorization (precise access control).

Section titled “Related Resources”

W3C Specifications

Section titled “W3C Specifications”

Vidos Documentation

Section titled “Vidos Documentation”