Which protocol facilitates sharing of information within a user profile between sites, allowing users to log in without sharing their password with the consumer site?

The correct protocol that facilitates sharing of information within a user profile between sites, allowing users to log in without sharing their password with the consumer site, is OAuth.

OAuth is an open standard for access delegation commonly used as a way to grant websites or applications limited access to a user's information without exposing passwords. When a user opts to log in using OAuth, they are redirected to the service that manages their credentials (for example, Google or Facebook), where they can authenticate. The service then provides an access token to the application requesting access. This token allows the application to request information from the user's profile from the OAuth provider without having direct access to the user’s passwords or other sensitive credentials. This not only enhances user security but also simplifies the authentication process.

In contrast, other protocols such as LDAPS, RADIUS, and Diameter serve different purposes. LDAPS is primarily used for securely accessing and maintaining directory information services over an encrypted connection, rather than handling user profile data between different consumer sites. RADIUS and Diameter are network protocols primarily involved in providing authentication, authorization, and accounting for network access rather than enabling third-party access to a user's identity securely. Thus, OAuth uniquely addresses the need for secure and shared access to user profiles across different platforms without revealing