This really doesn't solve the DDOS problem though. It's throwing more CPU time and bandwidth at a scenario that already requires both of those. It can slow a

This really doesn't solve the DDOS problem though. It's throwing more CPU time and bandwidth at a scenario that already requires both of those. It can slow a small group of script kiddies making a thousand requests to your server per second, but it doesn't stop an actual distributed attack using a botnet or large numbers of machines. If you're adding the signatures, you presumably need to spend CPU time to authenticate it, and bandwidth to send the data, plus the actual content. Why not just have the middle-man soak up the extra requests, cache the data, and fan it out that way?