Lightning Grim Anticheat

# Lightning Grim Anticheat This project is a fork of GrimAC implementing substantial performance improvements and superiour reach, block placement, and interact checks. If you would like a bugfix or enhancement and cannot sponsor the work, pull requests are welcome. GrimAC is an open source Minecraft anticheat designed for 1.21.5 and supports 1.8-1.21.5. It can run on 1.8-1.21.5 and fully supports players connecting through ViaVersion on 1.7-1.21.x no matter the native server version. Geyser players are fully exempt. ### Current changes that upstream does not have (includes but is not limited to) - WallHit - checks for hitting through walls - EntityPierce - checks for hitting through other entities - Bukkit Event Piston Optimizations - Optimized Hitbox/Collision Boxes - Optimized Reach calculations - Checks for PacketOrder (patches lots of noslow, autoblocks, etc...) - Checks for Inventory interactions (prevents using crafting slots as extra storage, moving while having inventory open, etc...) - ~~LineOfSightPlace - checks if blocks placements/container interactions were within line of sight of player. Stops placing blocks and opening chests through walls or in directions players aren't looking at.~~ ### Compiling through terminal/command prompt 1. git clone [https://github.com/Axionize/LightningGrim](https://github.com/Axionize/LightningGrim) (or click the green code button, download ZIP, then unzip it.) 2. cd LightningGrim 3. gradlew build 4. The final jar is located in build/libs ### API Information Grim's API allows you to integrate Grim into your own plugins. For more information, check out the API's GitHub repository [here](https://github.com/GrimAnticheat/GrimAPI). ## Grim supremacy Here are the main cores that make 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