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SeedShield

Cryptographic structure seed protection for Paper/Spigot servers.

中文 | English

SeedShield prevents seed cracking tools (chunkbase, SeedCrackerX, Structurecracker) from determining structure locations by replacing each structure type's placement salt with an irreversible SHA-256 derived value. Can work in main world / nether / end world.

This is the first Paper/Spigot plugin to provide cryptographic structure seed protection. Previously, this level of protection was only available through Fabric mods or custom server forks.

How It Works

Minecraft determines structure positions using this formula:

position = f(worldSeed, regionCoords, salt)

The salt is a hardcoded integer per structure type. Tools like chunkbase know these default salts, so knowing the world seed = knowing all structure locations.

SeedShield replaces each salt with:

salt = SHA-256(secretKey + ":" + worldSeed + ":" + structureType)[0..4]
  • Per-structure isolation: Each structure type gets a unique cryptographic salt. Cracking one type's salt reveals nothing about others.
  • Secret key protection: Without the 256-bit key (stored in config.yml), salts cannot be reversed.
  • Stronghold protection: Also modifies concentricRingsSeed and recalculates ring positions.

Installation

  1. Download SeedShield-1.0.0.jar from Releases
  2. Place it in your server's plugins/ folder
  3. Delete the region files of worlds you want to protect (structures must regenerate)
  4. Restart the server
  5. Edit plugins/SeedShield/config.yml to configure which worlds to protect

Important: SeedShield only affects newly generated chunks. Existing structures in already-generated chunks will not change positions.

Configuration

# Auto-generated 256-bit secret key. DO NOT SHARE.
secret-key: "a1b2c3d4..."

# Worlds to protect
enabled-worlds:
  - world
  - survival

Requirements

  • Paper 1.20.5+ (or forks: Leaves, Purpur, Folia, etc.)
  • Java 17+

Note: Versions 1.20.4 and below are not supported. Paper switched to Mojang mappings starting from 1.20.5, which this plugin relies on for reflection.

Security Analysis

Attack Vector Protection Level
chunkbase / online seed maps ✅ Fully defeated
SeedCrackerX client mod ✅ Defeated (combine with FakeSeed for hashed seed)
Brute-force single structure salt (2³² attempts) ⚠️ Possible per-type, but each type must be cracked independently
Reverse secret key from salt ✅ Infeasible (SHA-256 preimage resistance)
Cross-structure salt derivation ✅ Impossible without key

Building from Source

git clone https://github.com/7yunluo/SeedShield.git
cd SeedShield
mvn package

The JAR will be at target/SeedShield-1.0.0.jar.

License

MIT License