Schema Verification Policy Reference

This reference documents the schema verification policy for the verifier service. The schema policy validates that credential content conforms to defined schemas, ensuring data integrity and structural correctness.

Policy Overview

The schema verification policy validates the content of verifiable credentials against defined schemas to ensure the credential data adheres to expected structure and data types. This validation ensures credentials contain properly formatted data and helps maintain interoperability between different systems.

Supported Standards

The schema verification policy supports credential schema validation across multiple standards:

Standard	Organization	Specification	Schema Format	Validation Aspect
JSON Schema	IETF	JSON Schema	JSON Schema	Provides underlying schema validation technology for credential data
JSON-LD Context Validation	W3C	JSON-LD 1.1	JSON-LD Context	Validates against semantic data models defined in JSON-LD contexts
SD-JWT Verifiable Credential	IETF	SD-JWT Draft	JWT Claims	Validates JWT and SD-JWT claims against defined schemas
Verifiable Credentials JSON Schema	W3C	VC JSON Schema	JSON Schema	Validates credential claims against standard JSON Schema

Supported Schema Formats

The verifier supports the following credential schema validation implementations:

Schema Format	Description	Specification	Best For
W3C Verifiable Credential Schema	Schema validation for W3C VCs	W3C Recommendation	W3C VC validation using JSON Schema or JSON-LD Context
IETF Digital Credential Schema	Schema validation for IETF credentials	IETF Draft	SD-JWT and JWT credential validation

Schema Verification Process

flowchart TD
    subgraph "Schema Verification"
        Input[Credential] --> ExtractType[Extract Credential Type]
        ExtractType --> ResolveSchema[Resolve Schema]
        ResolveSchema --> ValidateContent[Validate Credential Content]
        ValidateContent --> Decision{Schema Valid?}
        Decision -->|Yes| Valid[Valid]
        Decision -->|No| Invalid[Invalid Schema]
    end

    SchemaRegistry[Schema Registry] -.-> |"Schema Retrieval"| ResolveSchema

    style Input fill:#f9f9f9,stroke:#333,stroke-width:1px
    style ExtractType fill:#e1f5fe,stroke:#333,stroke-width:1px
    style ResolveSchema fill:#e1f5fe,stroke:#333,stroke-width:1px
    style ValidateContent fill:#e1f5fe,stroke:#333,stroke-width:1px
    style Decision fill:#e1f5fe,stroke:#333,stroke-width:1px
    style Valid fill:#dcedc8,stroke:#333,stroke-width:1px
    style Invalid fill:#ffcdd2,stroke:#333,stroke-width:1px
    style SchemaRegistry fill:#fff9c4,stroke:#333,stroke-width:1px

When verifying against schemas, the policy follows these steps:

1. Type extraction - Identifies the credential type and associated schema
2. Schema resolution - Retrieves the schema from a schema registry or URI
3. Content validation - Validates the credential data against the schema
4. Result determination - Returns the validation result with any schema violations

Integration with Schema Registry

The schema policy integrates with schema registry services to:

1. Discover schemas based on credential types
2. Fetch schema definitions from URIs
3. Cache frequently used schemas for improved performance
4. Support versioned schemas for credential evolution

Error Handling

The schema policy returns specific errors for various validation failures:

Error Type	Description	Typical Cause
Schema Not Found	Cannot locate schema for validation	Missing or invalid schema reference
Schema Resolution Error	Error retrieving schema from URI	Network issues or invalid schema URI
Validation Error	Credential fails to validate against schema	Malformed credential data
Invalid Schema	Schema definition is invalid	Poorly structured schema
Unsupported Schema Type	Schema format not supported	Schema uses unsupported validation mechanism

Configuration

The schema verification policy offers various configuration options that control its behavior, including:

• Enabling or disabling schema validation
• Configuring schema resolution mechanisms
• Setting validation behavior for missing schemas
• Controlling error handling for validation failures
• Schema caching settings

For detailed configuration options, parameters, and default values, see the Verifier Configuration Reference.