diff --git a/COMPATIBILITY_MATRIX.md b/COMPATIBILITY_MATRIX.md
new file mode 100644
index 0000000..84a0ebe
--- /dev/null
+++ b/COMPATIBILITY_MATRIX.md
@@ -0,0 +1,19 @@
+# Compatibility Matrix
+
+Target support window: `1.16.5` through `1.21.11`.
+
+| Minecraft version | Module | Status |
+| --- | --- | --- |
+| 1.16.5 | `fabric-1.16.5` | Implemented (full logic) |
+| 1.17.1 | `fabric-1.17.1` | Build-ready port starter |
+| 1.18.2 | `fabric-1.18.2` | Build-ready port starter |
+| 1.19.4 | `fabric-1.19.4` | Build-ready port starter |
+| 1.20.1 | `fabric-1.20.1` | Build-ready port starter |
+| 1.21.1 | `fabric-1.21.1` | Build-ready port starter |
+| 1.21.10 | `fabric-1.21.10` | Build-ready port starter |
+| 1.21.11 | `fabric-1.21.11` | Build-ready port starter |
+
+Notes:
+- Shared cryptographic and seed conversion code is centralized in `common`.
+- World seed is enforced at exactly 1024 bits.
+- Version-specific worldgen mixins still need per-version migration to reach full runtime parity with 1.16.5 behavior.
diff --git a/README.md b/README.md
index 9ee5184..3b005b9 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,16 @@ State-of-the-art cryptography to protect your world seed against seed cracking t
 
 This mod is written for the Fabric Mod Loader. If you have advanced knowledge on coding Spigot plugins, help with porting this to Spigot would be greatly appreciated.
 
+## Project layout
+- `common`: shared code that does not depend on a specific Minecraft version (hashing, seed constants, seed parsing utilities, shared interfaces).
+- `fabric-1.16.5`: current working Fabric implementation for Minecraft 1.16.5.
+- `fabric-1.21.10`: Loom-based port start for Minecraft 1.21.10 with shared seed logic already wired.
+
+Security baseline:
+- World seed size is currently 1024 bits.
+- A runtime guard enforces exactly 1024 bits.
+- Supported version range is codified in `common` as `1.16.5` through `1.21.10`.
+
 ## How does it work?
 1. Increased the number of bits in the world seed from 64 to 1024. Although cracking a 64-bit seed with the other anti-seed-cracking measures is likely infeasible at the moment without access to a huge datacenter, we cannot rule out this possibility from the future, 1024 bits is likely to be safe for a *very* long time.
 1. Changed the random number generators from LCGs (and the homebrew RNG in the biome generator) to a fast cryptographically secure RNG based on the [BLAKE2](https://en.wikipedia.org/wiki/BLAKE_(hash_function)) secure hashing algorithm. This has a minor negative impact on performance of world gen, but ensures that players cannot derive any information about the world other than the blocks they can already see.
diff --git a/build.gradle b/build.gradle
index b72d4f1..229eb38 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,75 +1,112 @@
 plugins {
-    id 'fabric-loom' version '0.6-SNAPSHOT'
-    id 'maven-publish'
+    id 'base'
+    id 'fabric-loom' version '1.15.5' apply false
 }
 
-sourceCompatibility = JavaVersion.VERSION_1_8
-targetCompatibility = JavaVersion.VERSION_1_8
+allprojects {
+    group = project.maven_group
+    version = project.mod_version
 
-archivesBaseName = project.archives_base_name
-version = project.mod_version
-group = project.maven_group
+    repositories {
+        mavenCentral()
+        maven {
+            name = 'Fabric'
+            url = 'https://maven.fabricmc.net/'
+        }
+    }
+}
 
-dependencies {
-    //to change the versions see the gradle.properties file
-    minecraft "com.mojang:minecraft:${project.minecraft_version}"
-    mappings "net.fabricmc:yarn:${project.yarn_mappings}:v2"
-    modImplementation "net.fabricmc:fabric-loader:${project.loader_version}"
+subprojects {
+    apply plugin: 'maven-publish'
 
+    tasks.withType(JavaCompile).configureEach {
+        options.encoding = "UTF-8"
+    }
 
-    // PSA: Some older mods, compiled on Loom 0.2.1, might have outdated Maven POMs.
-    // You may need to force-disable transitiveness on them.
-}
+    if (project.name.startsWith("fabric-")) {
+        apply plugin: 'fabric-loom'
 
-processResources {
-    inputs.property "version", project.version
+        def mcVersion = project.name.substring(7)
+        def propSuffix = mcVersion.replace('.', '_')
 
-    from(sourceSets.main.resources.srcDirs) {
-        include "fabric.mod.json"
-        expand "version": project.version
-    }
+        def yarnMappings = rootProject.property("yarn_mappings_${propSuffix}")
+        def loaderVersion = rootProject.property("loader_version_${propSuffix}")
+        def javaRelease = rootProject.hasProperty("java_release_${propSuffix}") ? rootProject.property("java_release_${propSuffix}") as int : 8
 
-    from(sourceSets.main.resources.srcDirs) {
-        exclude "fabric.mod.json"
-    }
-}
+        java {
+            toolchain {
+                languageVersion = JavaLanguageVersion.of(rootProject.java_version as int)
+            }
+            withSourcesJar()
+        }
 
-// ensure that the encoding is set to UTF-8, no matter what the system default is
-// this fixes some edge cases with special characters not displaying correctly
-// see http://yodaconditions.net/blog/fix-for-java-file-encoding-problems-with-gradle.html
-tasks.withType(JavaCompile) {
-    options.encoding = "UTF-8"
-}
+        tasks.withType(JavaCompile).configureEach {
+            options.release = javaRelease
+        }
 
-// Loom will automatically attach sourcesJar to a RemapSourcesJar task and to the "build" task
-// if it is present.
-// If you remove this task, sources will not be generated.
-task sourcesJar(type: Jar, dependsOn: classes) {
-    classifier = "sources"
-    from sourceSets.main.allSource
-}
+        base {
+            archivesName = "${rootProject.archives_base_name}-mc${mcVersion}"
+        }
 
-jar {
-    from "LICENSE"
-}
+        dependencies {
+            implementation project(':common')
 
-// configure the maven publication
-publishing {
-    publications {
-        mavenJava(MavenPublication) {
-            // add all the jars that should be included when publishing to maven
-            artifact(remapJar) {
-                builtBy remapJar
+            minecraft "com.mojang:minecraft:${mcVersion}"
+            mappings "net.fabricmc:yarn:${yarnMappings}:v2"
+            modImplementation "net.fabricmc:fabric-loader:${loaderVersion}"
+        }
+
+        processResources {
+            inputs.property "version", project.version
+            filesMatching("fabric.mod.json") {
+                expand "version": project.version
             }
-            artifact(sourcesJar) {
-                builtBy remapSourcesJar
+        }
+
+        jar {
+            from "${rootProject.projectDir}/LICENSE"
+        }
+
+        publishing {
+            publications {
+                mavenJava(MavenPublication) {
+                    artifact(remapJar) {
+                        builtBy remapJar
+                    }
+                    artifact(tasks.named('sourcesJar')) {
+                        builtBy tasks.named('sourcesJar')
+                    }
+                }
             }
         }
+    } else if (project.name == "common") {
+        apply plugin: 'java-library'
+
+        java {
+            toolchain {
+                languageVersion = JavaLanguageVersion.of(rootProject.java_version as int)
+            }
+        }
+
+        tasks.withType(JavaCompile).configureEach {
+            options.release = 8
+        }
+
+        jar {
+            archiveBaseName = "${rootProject.archives_base_name}-common"
+        }
     }
+}
 
-    // select the repositories you want to publish to
-    repositories {
-        // uncomment to publish to the local maven
-        // mavenLocal()
+tasks.register("compatibilityMatrix") {
+    group = "help"
+    description = "Prints SecureSeed compatibility status for 1.16.5-1.21.10"
+    doLast {
+        println("1.16.5 -> implemented (fabric-1.16.5)")
+        println("1.17.x -> planned migration track")
+        println("1.18.x -> planned migration track")
+        println("1.19.x -> planned migration track")
+        println("1.20.x -> planned migration track")
+        println("1.21.10 -> port started (fabric-1.21.10)")
     }
 }
diff --git a/src/main/java/net/earthcomputer/secureseed/Hashing.java b/common/src/main/java/net/earthcomputer/secureseed/Hashing.java
similarity index 87%
rename from src/main/java/net/earthcomputer/secureseed/Hashing.java
rename to common/src/main/java/net/earthcomputer/secureseed/Hashing.java
index 51e0358..27bc3a0 100644
--- a/src/main/java/net/earthcomputer/secureseed/Hashing.java
+++ b/common/src/main/java/net/earthcomputer/secureseed/Hashing.java
@@ -28,14 +28,23 @@ public class Hashing {
     public static long[] hashWorldSeed(long[] worldSeed) {
         long[] result = blake2b_IV.clone();
         result[0] ^= 0x01010040;
+        if (worldSeed.length != SeedConstants.WORLD_SEED_LONGS) {
+            throw new IllegalArgumentException("worldSeed must have length " + SeedConstants.WORLD_SEED_LONGS);
+        }
         hash(worldSeed, result, new long[16], 0, false);
         return result;
     }
 
     public static void hash(long[] message, long[] chainValue, long[] internalState, long messageOffset, boolean isFinal) {
-        assert message.length == 16;
-        assert chainValue.length == 8;
-        assert internalState.length == 16;
+        if (message.length != 16) {
+            throw new IllegalArgumentException("message must have length 16");
+        }
+        if (chainValue.length != 8) {
+            throw new IllegalArgumentException("chainValue must have length 8");
+        }
+        if (internalState.length != 16) {
+            throw new IllegalArgumentException("internalState must have length 16");
+        }
 
         System.arraycopy(chainValue, 0, internalState, 0, chainValue.length);
         System.arraycopy(blake2b_IV, 0, internalState, chainValue.length, 4);
diff --git a/src/main/java/net/earthcomputer/secureseed/IChunkRandom.java b/common/src/main/java/net/earthcomputer/secureseed/IChunkRandom.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/IChunkRandom.java
rename to common/src/main/java/net/earthcomputer/secureseed/IChunkRandom.java
diff --git a/src/main/java/net/earthcomputer/secureseed/IGeneratorOptions.java b/common/src/main/java/net/earthcomputer/secureseed/IGeneratorOptions.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/IGeneratorOptions.java
rename to common/src/main/java/net/earthcomputer/secureseed/IGeneratorOptions.java
diff --git a/src/main/java/net/earthcomputer/secureseed/IMoreOptionsDialog.java b/common/src/main/java/net/earthcomputer/secureseed/IMoreOptionsDialog.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/IMoreOptionsDialog.java
rename to common/src/main/java/net/earthcomputer/secureseed/IMoreOptionsDialog.java
diff --git a/src/main/java/net/earthcomputer/secureseed/IWorldChunk.java b/common/src/main/java/net/earthcomputer/secureseed/IWorldChunk.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/IWorldChunk.java
rename to common/src/main/java/net/earthcomputer/secureseed/IWorldChunk.java
diff --git a/common/src/main/java/net/earthcomputer/secureseed/MinecraftVersionSupport.java b/common/src/main/java/net/earthcomputer/secureseed/MinecraftVersionSupport.java
new file mode 100644
index 0000000..c2e8ac2
--- /dev/null
+++ b/common/src/main/java/net/earthcomputer/secureseed/MinecraftVersionSupport.java
@@ -0,0 +1,33 @@
+package net.earthcomputer.secureseed;
+
+public final class MinecraftVersionSupport {
+    private MinecraftVersionSupport() {
+    }
+
+    public static final String MIN_SUPPORTED = "1.16.5";
+    public static final String MAX_SUPPORTED = "1.21.10";
+
+    public static boolean isWithinSupportedRange(String version) {
+        return compare(version, MIN_SUPPORTED) >= 0 && compare(version, MAX_SUPPORTED) <= 0;
+    }
+
+    private static int compare(String left, String right) {
+        int[] l = parse(left);
+        int[] r = parse(right);
+        for (int i = 0; i < 3; i++) {
+            if (l[i] != r[i]) {
+                return Integer.compare(l[i], r[i]);
+            }
+        }
+        return 0;
+    }
+
+    private static int[] parse(String version) {
+        String[] parts = version.split("\\.");
+        int[] parsed = new int[] {0, 0, 0};
+        for (int i = 0; i < parsed.length && i < parts.length; i++) {
+            parsed[i] = Integer.parseInt(parts[i]);
+        }
+        return parsed;
+    }
+}
diff --git a/common/src/main/java/net/earthcomputer/secureseed/SeedConstants.java b/common/src/main/java/net/earthcomputer/secureseed/SeedConstants.java
new file mode 100644
index 0000000..03391ee
--- /dev/null
+++ b/common/src/main/java/net/earthcomputer/secureseed/SeedConstants.java
@@ -0,0 +1,16 @@
+package net.earthcomputer.secureseed;
+
+public final class SeedConstants {
+    private SeedConstants() {
+    }
+
+    public static final int WORLD_SEED_LONGS = 16;
+    public static final int WORLD_SEED_BITS = WORLD_SEED_LONGS * 64;
+    public static final int REQUIRED_WORLD_SEED_BITS = 1024;
+
+    static {
+        if (WORLD_SEED_BITS != REQUIRED_WORLD_SEED_BITS) {
+            throw new IllegalStateException("WORLD_SEED_BITS must be exactly " + REQUIRED_WORLD_SEED_BITS);
+        }
+    }
+}
diff --git a/common/src/main/java/net/earthcomputer/secureseed/SeedUtils.java b/common/src/main/java/net/earthcomputer/secureseed/SeedUtils.java
new file mode 100644
index 0000000..d10210a
--- /dev/null
+++ b/common/src/main/java/net/earthcomputer/secureseed/SeedUtils.java
@@ -0,0 +1,48 @@
+package net.earthcomputer.secureseed;
+
+import java.math.BigInteger;
+import java.security.SecureRandom;
+
+public final class SeedUtils {
+    private SeedUtils() {
+    }
+
+    public static long[] createRandomWorldSeed() {
+        long[] seed = new long[SeedConstants.WORLD_SEED_LONGS];
+        SecureRandom rand = new SecureRandom();
+        for (int i = 0; i < SeedConstants.WORLD_SEED_LONGS; i++) {
+            seed[i] = rand.nextLong();
+        }
+        return seed;
+    }
+
+    public static long[] parseSeed(String seedStr) {
+        long[] seed = new long[SeedConstants.WORLD_SEED_LONGS];
+        try {
+            BigInteger seedBigInt = new BigInteger(seedStr);
+            if (seedBigInt.signum() < 0) {
+                seedBigInt = seedBigInt.and(BigInteger.ONE.shiftLeft(SeedConstants.WORLD_SEED_BITS).subtract(BigInteger.ONE));
+            }
+            for (int i = 0; i < SeedConstants.WORLD_SEED_LONGS; i++) {
+                BigInteger[] divRem = seedBigInt.divideAndRemainder(BigInteger.ONE.shiftLeft(64));
+                seed[i] = divRem[1].longValue();
+                seedBigInt = divRem[0];
+            }
+        } catch (NumberFormatException e) {
+            seed[0] = seedStr.hashCode();
+        }
+        return seed;
+    }
+
+    public static String seedToString(long[] seed) {
+        BigInteger seedBigInt = BigInteger.ZERO;
+        for (int i = SeedConstants.WORLD_SEED_LONGS - 1; i >= 0; i--) {
+            BigInteger val = BigInteger.valueOf(seed[i]);
+            if (val.signum() < 0) {
+                val = val.add(BigInteger.ONE.shiftLeft(64));
+            }
+            seedBigInt = seedBigInt.shiftLeft(64).add(val);
+        }
+        return seedBigInt.toString();
+    }
+}
diff --git a/src/main/java/net/earthcomputer/secureseed/Globals.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/Globals.java
similarity index 60%
rename from src/main/java/net/earthcomputer/secureseed/Globals.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/Globals.java
index 6c0109c..5c0abf4 100644
--- a/src/main/java/net/earthcomputer/secureseed/Globals.java
+++ b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/Globals.java
@@ -3,12 +3,10 @@
 import com.google.common.collect.Iterables;
 import net.minecraft.server.world.ServerWorld;
 
-import java.math.BigInteger;
-import java.security.SecureRandom;
-
 public class Globals {
-    public static final int WORLD_SEED_LONGS = 16;
-    public static final int WORLD_SEED_BITS = WORLD_SEED_LONGS * 64;
+    public static final int WORLD_SEED_LONGS = SeedConstants.WORLD_SEED_LONGS;
+    public static final int WORLD_SEED_BITS = SeedConstants.WORLD_SEED_BITS;
+    public static final int REQUIRED_WORLD_SEED_BITS = SeedConstants.REQUIRED_WORLD_SEED_BITS;
 
     public static final long[] worldSeed = new long[WORLD_SEED_LONGS];
     public static final ThreadLocal<Integer> dimension = ThreadLocal.withInitial(() -> 0);
@@ -45,43 +43,14 @@ public static void setupGlobals(ServerWorld world) {
     }
 
     public static long[] createRandomWorldSeed() {
-        long[] seed = new long[WORLD_SEED_LONGS];
-        SecureRandom rand = new SecureRandom();
-        for (int i = 0; i < WORLD_SEED_LONGS; i++) {
-            seed[i] = rand.nextLong();
-        }
-        return seed;
+        return SeedUtils.createRandomWorldSeed();
     }
 
     public static long[] parseSeed(String seedStr) {
-        long[] seed = new long[WORLD_SEED_LONGS];
-        try {
-            BigInteger seedBigInt = new BigInteger(seedStr);
-            if (seedBigInt.signum() < 0) {
-                seedBigInt = seedBigInt.and(BigInteger.ONE.shiftLeft(WORLD_SEED_BITS).subtract(BigInteger.ONE));
-            }
-            for (int i = 0; i < WORLD_SEED_LONGS; i++) {
-                BigInteger[] divRem = seedBigInt.divideAndRemainder(BigInteger.ONE.shiftLeft(64));
-                seed[i] = divRem[1].longValue();
-                seedBigInt = divRem[0];
-            }
-        } catch (NumberFormatException e) {
-            seed[0] = seedStr.hashCode();
-        }
-
-        return seed;
+        return SeedUtils.parseSeed(seedStr);
     }
 
     public static String seedToString(long[] seed) {
-        BigInteger seedBigInt = BigInteger.ZERO;
-        for (int i = WORLD_SEED_LONGS - 1; i >= 0; i--) {
-            BigInteger val = BigInteger.valueOf(seed[i]);
-            if (val.signum() < 0) {
-                val = val.add(BigInteger.ONE.shiftLeft(64));
-            }
-            seedBigInt = seedBigInt.shiftLeft(64).add(val);
-        }
-
-        return seedBigInt.toString();
+        return SeedUtils.seedToString(seed);
     }
 }
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/GeneratorOptionsAccessor.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/GeneratorOptionsAccessor.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/GeneratorOptionsAccessor.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/GeneratorOptionsAccessor.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinAbstractNetherSurfaceBuilder.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinAbstractNetherSurfaceBuilder.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinAbstractNetherSurfaceBuilder.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinAbstractNetherSurfaceBuilder.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinBadlandsSurfaceBuilder.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinBadlandsSurfaceBuilder.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinBadlandsSurfaceBuilder.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinBadlandsSurfaceBuilder.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinBiome.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinBiome.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinBiome.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinBiome.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinCachingLayerContext.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinCachingLayerContext.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinCachingLayerContext.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinCachingLayerContext.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinCarver.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinCarver.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinCarver.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinCarver.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinCaveCarver.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinCaveCarver.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinCaveCarver.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinCaveCarver.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkGenerator.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkGenerator.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkGenerator.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkGenerator.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkRandom.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkRandom.java
similarity index 88%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkRandom.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkRandom.java
index 5a3983b..3732b42 100644
--- a/src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkRandom.java
+++ b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkRandom.java
@@ -3,7 +3,6 @@
 import net.earthcomputer.secureseed.Globals;
 import net.earthcomputer.secureseed.Hashing;
 import net.earthcomputer.secureseed.IChunkRandom;
-import net.minecraft.util.math.MathHelper;
 import net.minecraft.world.gen.ChunkRandom;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Overwrite;
@@ -66,8 +65,8 @@ private void moreRandomBits() {
     public void secureseed_setSeed(long[] worldSeed, int x, int z, int dimension, int typeSalt, long salt) {
         System.arraycopy(worldSeed, 0, this.worldSeed, 0, Globals.WORLD_SEED_LONGS);
         message[0] = ((long) x << 32) | ((long) z & 0xffffffffL);
-        message[1] = ((long) dimension << 32) | ((long) salt & 0xffffffffL);
-        message[2] = typeSalt;
+        message[1] = ((long) dimension << 32) | ((long) typeSalt & 0xffffffffL);
+        message[2] = salt;
         message[3] = counter = 0;
         randomBitIndex = MAX_RANDOM_BIT_INDEX;
         secureSeeded = true;
@@ -85,6 +84,12 @@ public void secureseed_setInsecure() {
 
     @Unique
     private long getBits(int count) {
+        if (count < 0 || count > 64) {
+            throw new IllegalArgumentException("count must be in [0, 64], got " + count);
+        }
+        if (count == 0) {
+            return 0;
+        }
         if (!secureSeeded) {
             throw new IllegalStateException("Using unseeded ChunkRandom");
         }
@@ -96,21 +101,18 @@ private long getBits(int count) {
 
         int alignment = randomBitIndex & 63;
         if ((randomBitIndex >>> 6) == ((randomBitIndex + count) >>> 6)) {
-            long result = (randomBits[randomBitIndex >>> 6] >>> alignment) & ((1L << count) - 1);
+            long result = randomBits[randomBitIndex >>> 6] >>> alignment;
+            if (count != 64) {
+                result &= (1L << count) - 1;
+            }
             randomBitIndex += count;
             return result;
         } else {
-            long result = (randomBits[randomBitIndex >>> 6] >>> alignment) & ((1L << (64 - alignment)) - 1);
-            randomBitIndex += count;
-            if (randomBitIndex >= MAX_RANDOM_BIT_INDEX) {
-                moreRandomBits();
-                randomBitIndex -= MAX_RANDOM_BIT_INDEX;
-            }
-            alignment = randomBitIndex & 63;
-            result <<= alignment;
-            result |= (randomBits[randomBitIndex >>> 6] >>> (64 - alignment)) & ((1L << alignment) - 1);
-
-            return result;
+            int lowerCount = 64 - alignment;
+            long lower = randomBits[randomBitIndex >>> 6] >>> alignment;
+            randomBitIndex += lowerCount;
+            long upper = getBits(count - lowerCount);
+            return lower | (upper << lowerCount);
         }
     }
 
@@ -148,11 +150,14 @@ public void consume(int count) {
     @Override
     public int nextInt(int bound) {
         if (!secure) return super.nextInt(bound);
+        if (bound <= 0) {
+            throw new IllegalArgumentException("bound must be positive");
+        }
 
-        int bits = MathHelper.log2DeBruijn(bound);
+        int bits = 32 - Integer.numberOfLeadingZeros(bound - 1);
         int result;
         do {
-            result = (int) getBits(bits);
+            result = bits == 0 ? 0 : (int) getBits(bits);
         } while (result >= bound);
 
         return result;
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkStatus.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkStatus.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkStatus.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinChunkStatus.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinCreateWorldScreen.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinCreateWorldScreen.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinCreateWorldScreen.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinCreateWorldScreen.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinEndBiomeSource.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinEndBiomeSource.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinEndBiomeSource.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinEndBiomeSource.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinEndSpikeFeature.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinEndSpikeFeature.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinEndSpikeFeature.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinEndSpikeFeature.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinEnderDragonFight.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinEnderDragonFight.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinEnderDragonFight.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinEnderDragonFight.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinGeneratorOptions.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinGeneratorOptions.java
similarity index 94%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinGeneratorOptions.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinGeneratorOptions.java
index b8a0216..ade6594 100644
--- a/src/main/java/net/earthcomputer/secureseed/mixin/MixinGeneratorOptions.java
+++ b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinGeneratorOptions.java
@@ -35,12 +35,12 @@ public class MixinGeneratorOptions implements IGeneratorOptions {
 
     @Override
     public long[] secureseed_getSeed() {
-        return secureSeed;
+        return secureSeed == null ? null : secureSeed.clone();
     }
 
     @Override
     public void secureseed_setSeed(long[] seed) {
-        this.secureSeed = seed;
+        this.secureSeed = seed == null ? null : seed.clone();
         if (seed != null) this.seed = seed[0];
     }
 
@@ -81,7 +81,7 @@ private static <T1, T2, T3, T4, T5, R> App<RecordCodecBuilder.Mu<GeneratorOption
     @Inject(method = "fromProperties", at = @At("RETURN"))
     private static void parseSecureSeedFromLevelProperties(DynamicRegistryManager registryManager, Properties properties, CallbackInfoReturnable<GeneratorOptions> ci) {
         String seedStr = properties.getProperty("level-seed");
-        long[] seed = seedStr.isEmpty() ? Globals.createRandomWorldSeed() : Globals.parseSeed(seedStr);
+        long[] seed = seedStr == null || seedStr.isEmpty() ? Globals.createRandomWorldSeed() : Globals.parseSeed(seedStr);
         ((IGeneratorOptions) ci.getReturnValue()).secureseed_setSeed(seed);
     }
 }
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinMinecraftServer.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinMinecraftServer.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinMinecraftServer.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinMinecraftServer.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinMoreOptionsDialog.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinMoreOptionsDialog.java
similarity index 97%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinMoreOptionsDialog.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinMoreOptionsDialog.java
index 918abfc..c863740 100644
--- a/src/main/java/net/earthcomputer/secureseed/mixin/MixinMoreOptionsDialog.java
+++ b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinMoreOptionsDialog.java
@@ -57,6 +57,6 @@ private void setSecureSeedOnGeneratorOptions(CallbackInfoReturnable<GeneratorOpt
 
     @Override
     public void secureseed_setSeed(long[] seed) {
-        this.secureSeed = seed;
+        this.secureSeed = seed == null ? null : seed.clone();
     }
 }
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinMultiNoiseBiomeSource.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinMultiNoiseBiomeSource.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinMultiNoiseBiomeSource.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinMultiNoiseBiomeSource.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinNoiseChunkGenerator.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinNoiseChunkGenerator.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinNoiseChunkGenerator.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinNoiseChunkGenerator.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinOctavePerlinNoiseSampler.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinOctavePerlinNoiseSampler.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinOctavePerlinNoiseSampler.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinOctavePerlinNoiseSampler.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinOctaveSimplexNoiseSampler.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinOctaveSimplexNoiseSampler.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinOctaveSimplexNoiseSampler.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinOctaveSimplexNoiseSampler.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinPillagerOutpostFeature.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinPillagerOutpostFeature.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinPillagerOutpostFeature.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinPillagerOutpostFeature.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinRavineCarver.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinRavineCarver.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinRavineCarver.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinRavineCarver.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinSeedCommand.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinSeedCommand.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinSeedCommand.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinSeedCommand.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinServerChunkManager.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinServerChunkManager.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinServerChunkManager.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinServerChunkManager.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinServerWorld.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinServerWorld.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinServerWorld.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinServerWorld.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinSlimeEntity.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinSlimeEntity.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinSlimeEntity.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinSlimeEntity.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinSurfaceBuilders.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinSurfaceBuilders.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinSurfaceBuilders.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinSurfaceBuilders.java
diff --git a/src/main/java/net/earthcomputer/secureseed/mixin/MixinWorldChunk.java b/fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinWorldChunk.java
similarity index 100%
rename from src/main/java/net/earthcomputer/secureseed/mixin/MixinWorldChunk.java
rename to fabric-1.16.5/src/main/java/net/earthcomputer/secureseed/mixin/MixinWorldChunk.java
diff --git a/src/main/resources/assets/secureseed/icon.png b/fabric-1.16.5/src/main/resources/assets/secureseed/icon.png
similarity index 100%
rename from src/main/resources/assets/secureseed/icon.png
rename to fabric-1.16.5/src/main/resources/assets/secureseed/icon.png
diff --git a/src/main/resources/fabric.mod.json b/fabric-1.16.5/src/main/resources/fabric.mod.json
similarity index 100%
rename from src/main/resources/fabric.mod.json
rename to fabric-1.16.5/src/main/resources/fabric.mod.json
diff --git a/src/main/resources/secureseed.mixins.json b/fabric-1.16.5/src/main/resources/secureseed.mixins.json
similarity index 100%
rename from src/main/resources/secureseed.mixins.json
rename to fabric-1.16.5/src/main/resources/secureseed.mixins.json
diff --git a/fabric-1.17.1/src/main/java/net/earthcomputer/secureseed/PortStart.java b/fabric-1.17.1/src/main/java/net/earthcomputer/secureseed/PortStart.java
new file mode 100644
index 0000000..284ab9a
--- /dev/null
+++ b/fabric-1.17.1/src/main/java/net/earthcomputer/secureseed/PortStart.java
@@ -0,0 +1,14 @@
+package net.earthcomputer.secureseed;
+
+public final class PortStart {
+    private PortStart() {
+    }
+
+    public static long[] createPortSeed() {
+        return SeedUtils.createRandomWorldSeed();
+    }
+
+    public static int requiredSeedBits() {
+        return SeedConstants.REQUIRED_WORLD_SEED_BITS;
+    }
+}
diff --git a/fabric-1.17.1/src/main/resources/assets/secureseed/icon.png b/fabric-1.17.1/src/main/resources/assets/secureseed/icon.png
new file mode 100644
index 0000000..8b58a65
Binary files /dev/null and b/fabric-1.17.1/src/main/resources/assets/secureseed/icon.png differ
diff --git a/fabric-1.17.1/src/main/resources/fabric.mod.json b/fabric-1.17.1/src/main/resources/fabric.mod.json
new file mode 100644
index 0000000..8c21424
--- /dev/null
+++ b/fabric-1.17.1/src/main/resources/fabric.mod.json
@@ -0,0 +1,24 @@
+{
+  "schemaVersion": 1,
+  "id": "secureseed",
+  "version": "${version}",
+  "name": "SecureSeed",
+  "description": "State-of-the-art cryptography to protect your world seed against seed cracking tools",
+  "authors": [
+    "Earthcomputer"
+  ],
+  "contact": {
+    "website": "https://earthcomputer.net",
+    "repo": "https://github.com/Earthcomputer/SecureSeed"
+  },
+  "license": "MIT",
+  "icon": "assets/secureseed/icon.png",
+  "environment": "*",
+  "entrypoints": {},
+  "mixins": [
+    "secureseed-1.17.1.mixins.json"
+  ],
+  "depends": {
+    "fabricloader": ">=0.11.1"
+  }
+}
diff --git a/fabric-1.17.1/src/main/resources/secureseed-1.17.1.mixins.json b/fabric-1.17.1/src/main/resources/secureseed-1.17.1.mixins.json
new file mode 100644
index 0000000..ef0df29
--- /dev/null
+++ b/fabric-1.17.1/src/main/resources/secureseed-1.17.1.mixins.json
@@ -0,0 +1,11 @@
+{
+  "required": false,
+  "minVersion": "0.8",
+  "package": "net.earthcomputer.secureseed.mixin",
+  "compatibilityLevel": "JAVA_8",
+  "mixins": [],
+  "client": [],
+  "injectors": {
+    "defaultRequire": 1
+  }
+}
diff --git a/fabric-1.18.2/src/main/java/net/earthcomputer/secureseed/PortStart.java b/fabric-1.18.2/src/main/java/net/earthcomputer/secureseed/PortStart.java
new file mode 100644
index 0000000..284ab9a
--- /dev/null
+++ b/fabric-1.18.2/src/main/java/net/earthcomputer/secureseed/PortStart.java
@@ -0,0 +1,14 @@
+package net.earthcomputer.secureseed;
+
+public final class PortStart {
+    private PortStart() {
+    }
+
+    public static long[] createPortSeed() {
+        return SeedUtils.createRandomWorldSeed();
+    }
+
+    public static int requiredSeedBits() {
+        return SeedConstants.REQUIRED_WORLD_SEED_BITS;
+    }
+}
diff --git a/fabric-1.18.2/src/main/resources/assets/secureseed/icon.png b/fabric-1.18.2/src/main/resources/assets/secureseed/icon.png
new file mode 100644
index 0000000..8b58a65
Binary files /dev/null and b/fabric-1.18.2/src/main/resources/assets/secureseed/icon.png differ
diff --git a/fabric-1.18.2/src/main/resources/fabric.mod.json b/fabric-1.18.2/src/main/resources/fabric.mod.json
new file mode 100644
index 0000000..636b137
--- /dev/null
+++ b/fabric-1.18.2/src/main/resources/fabric.mod.json
@@ -0,0 +1,24 @@
+{
+  "schemaVersion": 1,
+  "id": "secureseed",
+  "version": "${version}",
+  "name": "SecureSeed",
+  "description": "State-of-the-art cryptography to protect your world seed against seed cracking tools",
+  "authors": [
+    "Earthcomputer"
+  ],
+  "contact": {
+    "website": "https://earthcomputer.net",
+    "repo": "https://github.com/Earthcomputer/SecureSeed"
+  },
+  "license": "MIT",
+  "icon": "assets/secureseed/icon.png",
+  "environment": "*",
+  "entrypoints": {},
+  "mixins": [
+    "secureseed-1.18.2.mixins.json"
+  ],
+  "depends": {
+    "fabricloader": ">=0.11.1"
+  }
+}
diff --git a/fabric-1.18.2/src/main/resources/secureseed-1.18.2.mixins.json b/fabric-1.18.2/src/main/resources/secureseed-1.18.2.mixins.json
new file mode 100644
index 0000000..ef0df29
--- /dev/null
+++ b/fabric-1.18.2/src/main/resources/secureseed-1.18.2.mixins.json
@@ -0,0 +1,11 @@
+{
+  "required": false,
+  "minVersion": "0.8",
+  "package": "net.earthcomputer.secureseed.mixin",
+  "compatibilityLevel": "JAVA_8",
+  "mixins": [],
+  "client": [],
+  "injectors": {
+    "defaultRequire": 1
+  }
+}
diff --git a/fabric-1.19.4/src/main/java/net/earthcomputer/secureseed/PortStart.java b/fabric-1.19.4/src/main/java/net/earthcomputer/secureseed/PortStart.java
new file mode 100644
index 0000000..284ab9a
--- /dev/null
+++ b/fabric-1.19.4/src/main/java/net/earthcomputer/secureseed/PortStart.java
@@ -0,0 +1,14 @@
+package net.earthcomputer.secureseed;
+
+public final class PortStart {
+    private PortStart() {
+    }
+
+    public static long[] createPortSeed() {
+        return SeedUtils.createRandomWorldSeed();
+    }
+
+    public static int requiredSeedBits() {
+        return SeedConstants.REQUIRED_WORLD_SEED_BITS;
+    }
+}
diff --git a/fabric-1.19.4/src/main/resources/assets/secureseed/icon.png b/fabric-1.19.4/src/main/resources/assets/secureseed/icon.png
new file mode 100644
index 0000000..8b58a65
Binary files /dev/null and b/fabric-1.19.4/src/main/resources/assets/secureseed/icon.png differ
diff --git a/fabric-1.19.4/src/main/resources/fabric.mod.json b/fabric-1.19.4/src/main/resources/fabric.mod.json
new file mode 100644
index 0000000..42089de
--- /dev/null
+++ b/fabric-1.19.4/src/main/resources/fabric.mod.json
@@ -0,0 +1,24 @@
+{
+  "schemaVersion": 1,
+  "id": "secureseed",
+  "version": "${version}",
+  "name": "SecureSeed",
+  "description": "State-of-the-art cryptography to protect your world seed against seed cracking tools",
+  "authors": [
+    "Earthcomputer"
+  ],
+  "contact": {
+    "website": "https://earthcomputer.net",
+    "repo": "https://github.com/Earthcomputer/SecureSeed"
+  },
+  "license": "MIT",
+  "icon": "assets/secureseed/icon.png",
+  "environment": "*",
+  "entrypoints": {},
+  "mixins": [
+    "secureseed-1.19.4.mixins.json"
+  ],
+  "depends": {
+    "fabricloader": ">=0.11.1"
+  }
+}
diff --git a/fabric-1.19.4/src/main/resources/secureseed-1.19.4.mixins.json b/fabric-1.19.4/src/main/resources/secureseed-1.19.4.mixins.json
new file mode 100644
index 0000000..ef0df29
--- /dev/null
+++ b/fabric-1.19.4/src/main/resources/secureseed-1.19.4.mixins.json
@@ -0,0 +1,11 @@
+{
+  "required": false,
+  "minVersion": "0.8",
+  "package": "net.earthcomputer.secureseed.mixin",
+  "compatibilityLevel": "JAVA_8",
+  "mixins": [],
+  "client": [],
+  "injectors": {
+    "defaultRequire": 1
+  }
+}
diff --git a/fabric-1.20.1/src/main/java/net/earthcomputer/secureseed/PortStart.java b/fabric-1.20.1/src/main/java/net/earthcomputer/secureseed/PortStart.java
new file mode 100644
index 0000000..284ab9a
--- /dev/null
+++ b/fabric-1.20.1/src/main/java/net/earthcomputer/secureseed/PortStart.java
@@ -0,0 +1,14 @@
+package net.earthcomputer.secureseed;
+
+public final class PortStart {
+    private PortStart() {
+    }
+
+    public static long[] createPortSeed() {
+        return SeedUtils.createRandomWorldSeed();
+    }
+
+    public static int requiredSeedBits() {
+        return SeedConstants.REQUIRED_WORLD_SEED_BITS;
+    }
+}
diff --git a/fabric-1.20.1/src/main/resources/assets/secureseed/icon.png b/fabric-1.20.1/src/main/resources/assets/secureseed/icon.png
new file mode 100644
index 0000000..8b58a65
Binary files /dev/null and b/fabric-1.20.1/src/main/resources/assets/secureseed/icon.png differ
diff --git a/fabric-1.20.1/src/main/resources/fabric.mod.json b/fabric-1.20.1/src/main/resources/fabric.mod.json
new file mode 100644
index 0000000..3011b7a
--- /dev/null
+++ b/fabric-1.20.1/src/main/resources/fabric.mod.json
@@ -0,0 +1,24 @@
+{
+  "schemaVersion": 1,
+  "id": "secureseed",
+  "version": "${version}",
+  "name": "SecureSeed",
+  "description": "State-of-the-art cryptography to protect your world seed against seed cracking tools",
+  "authors": [
+    "Earthcomputer"
+  ],
+  "contact": {
+    "website": "https://earthcomputer.net",
+    "repo": "https://github.com/Earthcomputer/SecureSeed"
+  },
+  "license": "MIT",
+  "icon": "assets/secureseed/icon.png",
+  "environment": "*",
+  "entrypoints": {},
+  "mixins": [
+    "secureseed-1.20.1.mixins.json"
+  ],
+  "depends": {
+    "fabricloader": ">=0.11.1"
+  }
+}
diff --git a/fabric-1.20.1/src/main/resources/secureseed-1.20.1.mixins.json b/fabric-1.20.1/src/main/resources/secureseed-1.20.1.mixins.json
new file mode 100644
index 0000000..ef0df29
--- /dev/null
+++ b/fabric-1.20.1/src/main/resources/secureseed-1.20.1.mixins.json
@@ -0,0 +1,11 @@
+{
+  "required": false,
+  "minVersion": "0.8",
+  "package": "net.earthcomputer.secureseed.mixin",
+  "compatibilityLevel": "JAVA_8",
+  "mixins": [],
+  "client": [],
+  "injectors": {
+    "defaultRequire": 1
+  }
+}
diff --git a/fabric-1.21.1/src/main/java/net/earthcomputer/secureseed/PortStart.java b/fabric-1.21.1/src/main/java/net/earthcomputer/secureseed/PortStart.java
new file mode 100644
index 0000000..284ab9a
--- /dev/null
+++ b/fabric-1.21.1/src/main/java/net/earthcomputer/secureseed/PortStart.java
@@ -0,0 +1,14 @@
+package net.earthcomputer.secureseed;
+
+public final class PortStart {
+    private PortStart() {
+    }
+
+    public static long[] createPortSeed() {
+        return SeedUtils.createRandomWorldSeed();
+    }
+
+    public static int requiredSeedBits() {
+        return SeedConstants.REQUIRED_WORLD_SEED_BITS;
+    }
+}
diff --git a/fabric-1.21.1/src/main/resources/assets/secureseed/icon.png b/fabric-1.21.1/src/main/resources/assets/secureseed/icon.png
new file mode 100644
index 0000000..8b58a65
Binary files /dev/null and b/fabric-1.21.1/src/main/resources/assets/secureseed/icon.png differ
diff --git a/fabric-1.21.1/src/main/resources/fabric.mod.json b/fabric-1.21.1/src/main/resources/fabric.mod.json
new file mode 100644
index 0000000..d646cfa
--- /dev/null
+++ b/fabric-1.21.1/src/main/resources/fabric.mod.json
@@ -0,0 +1,24 @@
+{
+  "schemaVersion": 1,
+  "id": "secureseed",
+  "version": "${version}",
+  "name": "SecureSeed",
+  "description": "State-of-the-art cryptography to protect your world seed against seed cracking tools",
+  "authors": [
+    "Earthcomputer"
+  ],
+  "contact": {
+    "website": "https://earthcomputer.net",
+    "repo": "https://github.com/Earthcomputer/SecureSeed"
+  },
+  "license": "MIT",
+  "icon": "assets/secureseed/icon.png",
+  "environment": "*",
+  "entrypoints": {},
+  "mixins": [
+    "secureseed-1.21.1.mixins.json"
+  ],
+  "depends": {
+    "fabricloader": ">=0.11.1"
+  }
+}
diff --git a/fabric-1.21.1/src/main/resources/secureseed-1.21.1.mixins.json b/fabric-1.21.1/src/main/resources/secureseed-1.21.1.mixins.json
new file mode 100644
index 0000000..ef0df29
--- /dev/null
+++ b/fabric-1.21.1/src/main/resources/secureseed-1.21.1.mixins.json
@@ -0,0 +1,11 @@
+{
+  "required": false,
+  "minVersion": "0.8",
+  "package": "net.earthcomputer.secureseed.mixin",
+  "compatibilityLevel": "JAVA_8",
+  "mixins": [],
+  "client": [],
+  "injectors": {
+    "defaultRequire": 1
+  }
+}
diff --git a/fabric-1.21.10/README.md b/fabric-1.21.10/README.md
new file mode 100644
index 0000000..66d6edb
--- /dev/null
+++ b/fabric-1.21.10/README.md
@@ -0,0 +1,7 @@
+# fabric-1.21.10
+This module is the migration target for Minecraft 1.21.10.
+
+Current status:
+- Dedicated Loom module is configured.
+- Shared seed utilities from `common` are wired.
+- Version-specific mixins and mappings from `fabric-1.16.5` still need to be ported.
diff --git a/fabric-1.21.10/src/main/java/net/earthcomputer/secureseed/PortStart.java b/fabric-1.21.10/src/main/java/net/earthcomputer/secureseed/PortStart.java
new file mode 100644
index 0000000..284ab9a
--- /dev/null
+++ b/fabric-1.21.10/src/main/java/net/earthcomputer/secureseed/PortStart.java
@@ -0,0 +1,14 @@
+package net.earthcomputer.secureseed;
+
+public final class PortStart {
+    private PortStart() {
+    }
+
+    public static long[] createPortSeed() {
+        return SeedUtils.createRandomWorldSeed();
+    }
+
+    public static int requiredSeedBits() {
+        return SeedConstants.REQUIRED_WORLD_SEED_BITS;
+    }
+}
diff --git a/fabric-1.21.10/src/main/resources/assets/secureseed/icon.png b/fabric-1.21.10/src/main/resources/assets/secureseed/icon.png
new file mode 100644
index 0000000..8b58a65
Binary files /dev/null and b/fabric-1.21.10/src/main/resources/assets/secureseed/icon.png differ
diff --git a/fabric-1.21.10/src/main/resources/fabric.mod.json b/fabric-1.21.10/src/main/resources/fabric.mod.json
new file mode 100644
index 0000000..b6ecbf1
--- /dev/null
+++ b/fabric-1.21.10/src/main/resources/fabric.mod.json
@@ -0,0 +1,24 @@
+{
+  "schemaVersion": 1,
+  "id": "secureseed",
+  "version": "${version}",
+  "name": "SecureSeed",
+  "description": "State-of-the-art cryptography to protect your world seed against seed cracking tools",
+  "authors": [
+    "Earthcomputer"
+  ],
+  "contact": {
+    "website": "https://earthcomputer.net",
+    "repo": "https://github.com/Earthcomputer/SecureSeed"
+  },
+  "license": "MIT",
+  "icon": "assets/secureseed/icon.png",
+  "environment": "*",
+  "entrypoints": {},
+  "mixins": [
+    "secureseed-1.21.10.mixins.json"
+  ],
+  "depends": {
+    "fabricloader": ">=0.11.1"
+  }
+}
diff --git a/fabric-1.21.10/src/main/resources/secureseed-1.21.10.mixins.json b/fabric-1.21.10/src/main/resources/secureseed-1.21.10.mixins.json
new file mode 100644
index 0000000..ef0df29
--- /dev/null
+++ b/fabric-1.21.10/src/main/resources/secureseed-1.21.10.mixins.json
@@ -0,0 +1,11 @@
+{
+  "required": false,
+  "minVersion": "0.8",
+  "package": "net.earthcomputer.secureseed.mixin",
+  "compatibilityLevel": "JAVA_8",
+  "mixins": [],
+  "client": [],
+  "injectors": {
+    "defaultRequire": 1
+  }
+}
diff --git a/fabric-1.21.11/src/main/java/net/earthcomputer/secureseed/PortStart.java b/fabric-1.21.11/src/main/java/net/earthcomputer/secureseed/PortStart.java
new file mode 100644
index 0000000..284ab9a
--- /dev/null
+++ b/fabric-1.21.11/src/main/java/net/earthcomputer/secureseed/PortStart.java
@@ -0,0 +1,14 @@
+package net.earthcomputer.secureseed;
+
+public final class PortStart {
+    private PortStart() {
+    }
+
+    public static long[] createPortSeed() {
+        return SeedUtils.createRandomWorldSeed();
+    }
+
+    public static int requiredSeedBits() {
+        return SeedConstants.REQUIRED_WORLD_SEED_BITS;
+    }
+}
diff --git a/fabric-1.21.11/src/main/resources/assets/secureseed/icon.png b/fabric-1.21.11/src/main/resources/assets/secureseed/icon.png
new file mode 100644
index 0000000..8b58a65
Binary files /dev/null and b/fabric-1.21.11/src/main/resources/assets/secureseed/icon.png differ
diff --git a/fabric-1.21.11/src/main/resources/fabric.mod.json b/fabric-1.21.11/src/main/resources/fabric.mod.json
new file mode 100644
index 0000000..9353d7e
--- /dev/null
+++ b/fabric-1.21.11/src/main/resources/fabric.mod.json
@@ -0,0 +1,24 @@
+{
+  "schemaVersion": 1,
+  "id": "secureseed",
+  "version": "${version}",
+  "name": "SecureSeed",
+  "description": "State-of-the-art cryptography to protect your world seed against seed cracking tools",
+  "authors": [
+    "Earthcomputer"
+  ],
+  "contact": {
+    "website": "https://earthcomputer.net",
+    "repo": "https://github.com/Earthcomputer/SecureSeed"
+  },
+  "license": "MIT",
+  "icon": "assets/secureseed/icon.png",
+  "environment": "*",
+  "entrypoints": {},
+  "mixins": [
+    "secureseed-1.21.11.mixins.json"
+  ],
+  "depends": {
+    "fabricloader": ">=0.11.1"
+  }
+}
diff --git a/fabric-1.21.11/src/main/resources/secureseed-1.21.11.mixins.json b/fabric-1.21.11/src/main/resources/secureseed-1.21.11.mixins.json
new file mode 100644
index 0000000..ef0df29
--- /dev/null
+++ b/fabric-1.21.11/src/main/resources/secureseed-1.21.11.mixins.json
@@ -0,0 +1,11 @@
+{
+  "required": false,
+  "minVersion": "0.8",
+  "package": "net.earthcomputer.secureseed.mixin",
+  "compatibilityLevel": "JAVA_8",
+  "mixins": [],
+  "client": [],
+  "injectors": {
+    "defaultRequire": 1
+  }
+}
diff --git a/gradle.properties b/gradle.properties
index 9d6138b..9629205 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,12 +1,51 @@
 # Done to increase the memory available to gradle.
 org.gradle.jvmargs=-Xmx1G
-# Fabric Properties
-# check these on https://modmuss50.me/fabric.html
-minecraft_version=1.16.5
-yarn_mappings=1.16.5+build.4
-loader_version=0.11.1
+java_version=21
+# Fabric 1.16.5 Properties
+loom_version_1_16_5=1.15.5
+minecraft_version_1_16_5=1.16.5
+yarn_mappings_1_16_5=1.16.5+build.4
+loader_version_1_16_5=0.11.1
+
+# Fabric 1.21.10 target (port start)
+loom_version_1_21_10=1.15.5
+minecraft_version_1_21_10=1.21.10
+yarn_mappings_1_21_10=1.21.10+build.3
+loader_version_1_21_10=0.19.1
+
 # Mod Properties
 mod_version=0.1
 maven_group=net.earthcomputer
 archives_base_name=secureseed
 
+loom_version_1_17_1=1.15.5
+minecraft_version_1_17_1=1.17.1
+yarn_mappings_1_17_1=1.17.1+build.65
+loader_version_1_17_1=0.19.1
+java_release_1_17_1=16
+loom_version_1_18_2=1.15.5
+minecraft_version_1_18_2=1.18.2
+yarn_mappings_1_18_2=1.18.2+build.4
+loader_version_1_18_2=0.19.1
+java_release_1_18_2=17
+loom_version_1_19_4=1.15.5
+minecraft_version_1_19_4=1.19.4
+yarn_mappings_1_19_4=1.19.4+build.2
+loader_version_1_19_4=0.19.1
+java_release_1_19_4=17
+loom_version_1_20_1=1.15.5
+minecraft_version_1_20_1=1.20.1
+yarn_mappings_1_20_1=1.20.1+build.10
+loader_version_1_20_1=0.19.1
+java_release_1_20_1=17
+loom_version_1_21_1=1.15.5
+minecraft_version_1_21_1=1.21.1
+yarn_mappings_1_21_1=1.21.1+build.3
+loader_version_1_21_1=0.19.1
+java_release_1_21_1=21
+java_release_1_21_10=21
+loom_version_1_21_11=1.15.5
+minecraft_version_1_21_11=1.21.11
+yarn_mappings_1_21_11=1.21.11+build.4
+loader_version_1_21_11=0.19.1
+java_release_1_21_11=21
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index bb8b2fc..63e0e83 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.5.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.2.0-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/settings.gradle b/settings.gradle
index 5b60df3..1035597 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1,6 +1,6 @@
 pluginManagement {
     repositories {
-        jcenter()
+        mavenCentral()
         maven {
             name = 'Fabric'
             url = 'https://maven.fabricmc.net/'
@@ -8,3 +8,15 @@ pluginManagement {
         gradlePluginPortal()
     }
 }
+
+rootProject.name = 'SecureSeed'
+
+include 'common'
+include 'fabric-1.16.5'
+include 'fabric-1.17.1'
+include 'fabric-1.18.2'
+include 'fabric-1.19.4'
+include 'fabric-1.20.1'
+include 'fabric-1.21.1'
+include 'fabric-1.21.10'
+include 'fabric-1.21.11'