Freenet actually does this, though they aren't just sending random chaff, they'll actually use it to duplicate the data. It makes this particular attack imposs

Freenet actually does this, though they aren't just sending random chaff, they'll actually use it to duplicate the data. It makes this particular attack impossible, but freenet has it's own potential issues. If you control all of someone's inputs and outputs you can still determine when they are using the system.