Module ngx_http_secure_link_module
The ngx_http_secure_link_module module (0.7.18) is used to check authenticity of requested links, protect resources from unauthorized access, and limit link lifetime.
The authenticity of a requested link is verified by comparing the checksum value passed in a request with the value computed for the request. If a link has a limited lifetime and the time has expired, the link is considered outdated. The status of these checks is made available in the $secure_link variable.
The module provides two alternative operation modes. The first mode is enabled by the secure_link_secret directive and is used to check authenticity of requested links as well as protect resources from unauthorized access. The second mode (0.8.50) is enabled by the secure_link and secure_link_md5 directives and is also used to limit lifetime of links.
This module is not built by default, it should be enabled with the --with-http_secure_link_module configuration parameter.