The AuthGuard® authentication server is a client-server application developed using JSP/Servlet technologies. The client program runs in a browser as either a Java Applet or HTML/JavaScript based application. AuthGuard® can be configured to protect content and application servers. AuthGuard® authentication server employs a multi-tenant architecture enabling different authentication groups to login with different authentication methods/credentials. When a user attempts to access contents or services from a protected server, the server redirects that user to the AuthGuard® authentication dialog. The dialog is based on AuthGuard®’s authentication methods permitted/mandated by the administrator including the methods based on the patented Random Partial Shared Secret Recognition algorithm (RPSSR). Once the user is authenticated, the protected server allows the user to access the protected content. The login process also employs a highly secure FIPS 140-2 certified cryptographic module, and an encryption key management system integrated with the RPSSR authentication protocol; the combination of these assures high security level at credential entry devices, communication lines, and databases during every session’s user authentication process.