Trusted Linker Download Redirection (TLDR)
Bennish.net
This document describes an HTTP extension that allows user agents to verify downloaded data. It provides a standardised way for an HTTPS URL (assumed trustworthy) to redirect to a non-HTTPS URL and give the user agent extra information about the resulting output (e.g. a downloaded file.) Once that is retrieved, it can check whether or not the data has been modified since the trustworthy site checked it (e.g. altered during transit or as a result of the destination site having been compromised.)