Which authentication method will you implement when your company opens up its directory services to a partner company?

Implementing federation as an authentication method when a company opens its directory services to a partner organization is a strategic choice for facilitating secure access. Federation allows different organizations to establish a trust relationship wherein they share authentication tokens or credentials. This means that users from the partner company can authenticate with their own organization's credentials and gain access to specific resources in your directory without needing to create separate accounts.

This method is particularly beneficial when collaborating with external partners, as it streamlines the user experience by allowing single sign-on capabilities while maintaining the necessary security and control over access rights and permissions. By leveraging established federated identity standards such as SAML (Security Assertion Markup Language) or OAuth, this approach also enhances interoperability between different systems and services.

While directory services and single sign-on are important elements of user authentication, they do not specifically address the external partnership context as effectively as federation does. Additionally, attestation, which typically verifies the authenticity of a device or system's state, does not pertain directly to user authentication in the context of opening up directory services to partners.