This is a discussion topic for the Ore project, NoXray. View the full project on Ore for downloads and more information.
NoXray
NoXray is a mixin plugin that works on SpongeVanilla and SpongeForge. Thanks to mixins I was able to make a system that is effective and doesn’t lag that much. It works by modifying the chunks at send time and updating surrounding blocks when players break a block. Please note that ores in caves are visible, due to the fact that their is an air-block next to it, but this should slow down people that xray very effectively .