What method should be recommended for organizations using Microsoft 365 that require single sign-on with smart cards or certificates?

The recommended method for organizations using Microsoft 365 that require single sign-on with smart cards or certificates is Federated Authentication. This approach allows users to authenticate with their organization's identity provider through Single Sign-On (SSO), enabling them to access multiple applications without needing to re-enter their credentials.

Federated Authentication leverages established protocols such as SAML (Security Assertion Markup Language) or WS-Federation, which support the use of smart cards and certificates effectively, ensuring a secure and seamless user experience. By employing this method, organizations can enhance their security posture while simplifying the login process for users who must authenticate using smart cards or certificate-based logins.

This method is particularly valuable in scenarios where enhanced security is paramount, such as in government or financial sectors, where the use of strong authentication measures like smart cards is often required.

Other methods, like Basic Authentication, do not provide the level of security needed for environments that require smart card integration; OAuth 2.0 is primarily designed for delegated access, and while Multi-Factor Authentication adds an extra layer of security, it doesn’t specifically address the integration of smart cards or certificates for authentication.