Relying Party

A Relying Party (RP) is an entity (such as a website, application, or service) that relies on an identity provider (IdP) or authentication mechanism to verify a user's identity before granting access to resources.

In the context of authentication and security protocols, an RP does not authenticate users directly but instead depends o n a trusted third party, such as a FIDO2 authenticator, an OpenID Connect (OIDC) provider, or a certificate authority (CA), to perform authentication and validation.

Role of a Relying Party in Authentication Workflows

A Relying Party (RP) is a critical component in authentication and identity management, ensuring that users authenticate securely via trusted identity providers or cryptographic authentication mechanisms before accessing sensitive resources.

Identity Verification Process

When a user attempts to log in, the RP:

  1. Redirects the authentication request to an Identity Provider (IdP) or authentication system (e.g., FIDO2, OAuth, SAML).
  2. Receives an authentication response (e.g., signed assertion, token, or cryptographic proof).
  3. Validates the response and grants or denies access.

Security Enforcement

The RP ensures that authentication methods meet security requirements, such as:

  • Multi-Factor Authentication (MFA) (e.g., FIDO2, SMS OTP, biometrics).
  • Certificate-based authentication (e.g., PIV/CAC smart cards).
  • Federated authentication (e.g., Single Sign-On [SSO] with OAuth or SAML).

Examples of Relying Parties

  • In FIDO2 Authentication
    • A web application (e.g., a government portal or banking website) acts as an RP.
    • It requests a public key-based authentication from a user’s registered authenticator (e.g., security key, biometrics).
    • The RP verifies the cryptographic signature before granting access.
  • In Federated Identity (OIDC/SAML)
    • A cloud application (e.g., Google Workspace, Salesforce) is an RP that relies on an enterprise IdP (e.g., Okta, Azure AD) for authentication.
    • The RP validates the security token (e.g., OIDC ID Token, SAML Assertion) before allowing access.
  • In Certificate-Based Authentication
    • A VPN or enterprise system acts as an RP, requiring users to authenticate using PKI-based smart cards (e.g., PIV, CAC).
    • The RP validates the digital certificate before allowing network access.