#About Verifier

The verifier is a core service in the Vidos ecosystem that validates digital credentials, signatures, and claims according to various verification policies and standards. It ensures the cryptographic integrity, temporal validity, and compliance with defined rules for digital credentials from the perspective of the issuer, providing a critical trust layer for verification workflows.

#Why use a Verifier?

In digital trust ecosystems, verification is essential for establishing confidence in credentials and claims. The Verifier provides:

• Reliable validation of digital credentials against configurable policies
• Standards compliance across various credential formats and proof types
• Flexible verification rules to meet specific organizational requirements
• Comprehensive checks from cryptographic validation to temporal constraints
• Standardized results that clearly indicate verification status

By automating the complex verification process, the Verifier enables applications to make informed trust decisions without needing to implement complex cryptographic validation logic.

#What is a Verifier?

A verifier functions as a trusted validation service that assesses the authenticity and validity of digital credentials and presentations. It processes input credentials or presentations and returns detailed verification results that indicate whether the credential meets the defined trust requirements.

The Verifier performs multiple policy checks including:

• Proof verification - Validating digital signatures and cryptographic proofs to confirm the credential was truly issued by the claimed issuer
• Format validation - Ensuring credentials conform to expected standards as defined by the issuer
• Temporal checks - Verifying that credentials are within their validity period as established by the issuer
• Status verification - Checking if credentials have been revoked by the issuer
• Schema validation - Validating that credentials conform to their defined schemas as specified by the issuer

#Verifier Architecture

The Verifier in Vidos has two main components that work together to provide verification services:

1. Verifier Service: The core implementation that handles the verification process according to configurable policies
2. Verifier Management Service: Enables configuration and management of verifier instances for different verification needs

Vidos supports creating multiple verifier instances, each with its own policy configuration, to support different verification requirements within your organization.

The Verifier works closely with other Vidos services:

• Interacts with the Resolver to retrieve cryptographic material needed for verification
• Relies on the Validator for schema validation
• Provides verification results to the Authorizer for access control decisions

#Verification Process

When a credential is submitted for verification, the Verifier performs a series of policy checks from the issuer's perspective:

1. Format validation - Confirms the credential follows the expected data structure
2. Proof verification - Validates digital signatures by verifying cryptographic proofs
3. Temporal verification - Checks if the credential is within its validity period
4. Status verification - Ensures the credential hasn't been revoked
5. Schema validation - Verifies the credential adheres to its defined schema
6. Additional policy checks - Applies any custom verification policies configured for the instance

Each check can be individually configured or disabled to meet specific verification requirements.

#Use Cases

The Verifier Service supports various verification scenarios:

• Credential validation - Verify the authenticity and validity of digital credentials
• Access control - Support policy-based authorization decisions
• Compliance verification - Ensure credentials meet regulatory requirements
• Trust chain validation - Validate complex nested credential structures
• Multi-format verification - Support different credential formats through a unified interface

By providing configurable verification policies, the Verifier Service enables customized trust decisions based on your organization's specific requirements while maintaining focus on validating that the credential was properly issued and remains valid according to the issuer's parameters.

#Summary

The Verifier is a critical service in the Vidos ecosystem that:

• Validates the integrity and authenticity of digital credentials
• Applies configurable verification policies to support diverse trust requirements
• Provides clear, structured verification results for making trust decisions
• Integrates with other Vidos services to enable comprehensive trust solutions
• Supports multiple credential formats and proof types through a unified interface

By offering standardized verification capabilities, the Verifier simplifies the implementation of trusted digital interactions across your applications and services.