secure_link

Defines a string with variables from which the checksum value and lifetime of a link will be extracted.

Variables used in an expression are usually associated with a request; see example below.

The checksum value extracted from the string is compared with the MD5 hash value of the expression defined by the secure_link_md5 directive. If the checksums are different, the $secure_link variable is set to an empty string. If the checksums are the same, the link lifetime is checked. If the link has a limited lifetime and the time has expired, the $secure_link variable is set to “0”. Otherwise, it is set to “1”. The MD5 hash value passed in a request is encoded in base64url.

If a link has a limited lifetime, the expiration time is set in seconds since Epoch (Thu, 01 Jan 1970 00:00:00 GMT). The value is specified in the expression after the MD5 hash, and is separated by a comma. The expiration time passed in a request is available through the $secure_link_expires variable for a use in the secure_link_md5 directive. If the expiration time is not specified, a link has the unlimited lifetime.