Security token intro

Security tokens or URL tokens are a way to give users access permission for various Web resources. It is a technique involving Stealth Redirection or URL Hiding to ensure that your visitors see the original domain name and not the destination URL. 
Secure URLs indicate that hackers or other unwanted prying eyes cannot intercept the information transmitted from the browser to the server. For additional protection against access by unauthorized clients, you can use directives from the Secure Link module to require that clients include a specific hashed string in the URL of the asset they are requesting.
 
The Security Token module verifies a requested resource's validity by comparing an encoded string in the URL of the HTTP request with the string it computes for that request. If a link has a limited lifetime and the time has expired, the link is considered outdated.