idcheck
apache cookie SSO mechanism.
...The server uses a private cookie scoped only for the client browser and the idcheck webserver which is always protected with SSL.
In addition to the common practise of using SSL for everything (which idcheck supports). The idcheck system can also be used to provide authentication to websites where you merely want to hide content from various people. For example, an intranet whose contents are available to thousands of people. This is, in fact, its main advantage and feature.
Please check the wiki pages for more info (link above).
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