Which method allows for alternative ways of authentication and is based on the principles of federated identity systems?

The method that allows for alternative ways of authentication and is grounded in the principles of federated identity systems is OpenID. This protocol facilitates a single sign-on (SSO) experience across multiple sites by enabling users to authenticate with a single identity from a trusted provider. In federated identity systems, users maintain a single identity that they can use across different platforms and services without needing to create multiple credentials. OpenID achieves this by providing a way for users to log in using their existing accounts at participating providers, thereby simplifying the authentication process and enhancing user convenience.

OpenID's focus on user-managed identity and its capability to interact with various applications aligns with the fundamental objectives of federated identity systems, which aim to provide seamless access and interoperability among different systems while maintaining secure authentication processes. This decentralization of identity management is essential in promoting safer and more flexible interaction within the digital ecosystem, making OpenID a significant player in this realm.