Grim Anticheat

# GrimAC GrimAC is an free open source Minecraft anticheat designed to support the latest versions of Minecraft. It currently supports minecraft versions 1.8-1.21. Geyser players are fully exempt. This project is considered feature-complete for the 2.0 (open-source) branch. If you would like a bug fix or enhancement and cannot sponsor the work, pull requests are welcome. A premium version is planned, which will offer additional subscription-based paid checks, such as heuristics. ## Installation notes - **Java 17 is now required.** More information [here](https://github.com/GrimAnticheat/Grim/wiki/Updating-to-Java-17). - Paper, Spigot, and Folia are currently supported. - If you use Geyser, place Floodgate on the backend server so grim can exempt bedrock players. Grim cannot access the Floodgate API if it is on the proxy. - If you use ViaVersion, it should be on the backend server as movement is highly dependent on client version. ## Support & wiki information - Support & discussion: [Discord](https://discord.grim.ac) - Report issues: [Issues](https://github.com/GrimAnticheat/Grim/issues/new/choose) - Wiki & examples: [Wiki](https://github.com/GrimAnticheat/Grim/wiki) ## Developer API Grim's API allows you to integrate Grim into your own plugins. - API repository: [GrimAPI](https://github.com/GrimAnticheat/GrimAPI) - Wiki info: [Wiki](https://github.com/GrimAnticheat/GrimAPI) ## How to compile 1. `git clone https://github.com/GrimAnticheat/Grim.git` 2. `cd Grim` 3. `./gradlew build` 4. The final jar will compile into the build/libs folder ## Grim supremacy What makes Grim stand out against other anticheats? ### Movement Simulation Engine * We have a 1:1 replication of the player's possible movements * This covers everything from basic walking, swimming, knockback, cobwebs, to bubble columns * It even covers riding entities from boats to pigs to striders * Built upon covering edge cases to confirm accuracy * 1.13+ clients on 1.13+ servers, 1.12- clients on 1.13+ servers, 1.13+ clients on 1.12- servers, and 1.12- clients on 1.12- servers are all supported regardless of the large technical changes between these versions. * The order of collisions depends on the client version and is correct * Accounts for minor bounding box differences between versions, for example: * Single glass panes will be a + shape for 1.7-1.8 players and * for 1.9+ players * 1.13+ clients on 1.8 servers see the + glass pane hitbox due to ViaVersion * Many other blocks have this extreme attention to detail. * Waterlogged blocks do not exist for 1.12 or below players * Blocks that do not exist in the client's version use ViaVersion's replacement block * Block data that cannot be translated to previous versions is replaced correctly * All vanilla collision boxes have been implemented ### Fully asynchronous and multithreaded design * All movement checks and the overwhelming majority of listeners run on the netty thread * The anticheat can scale to many hundreds of players, if not more * Thread safety is carefully thought out * The next core allows for this design ### Full world replication * The anticheat keeps a replica of the world for each player * The replica is created by listening to chunk data packets, block places, and block changes * On all versions, chunks are compressed to 16-64 kb per chunk using palettes * Using this cache, the anticheat can safely access the world state * Per player, the cache allows for multithreaded design * Sending players fake blocks with packets is safe and does not lead to falses * The world is recreated for each player to allow lag compensation * Client sided blocks cause no issues with packet based blocks. Block glitching does not false the anticheat. ### Latency compensation * World changes are queued until they reach the player * This means breaking blocks under a player does not false the anticheat * Everything from flying status to movement speed will be latency compensated ### Inventory compensation * The player's inventory is tracked to prevent ghost blocks at high latency, and other errors ### Secure by design, not obscurity * All systems are designed to be highly secure and mathematically impossible to bypass * For example, the prediction engine knows all possible movements and cannot be bypassed