slime_seed_finder

This program finds minecraft world generation seeds using slime chunks and biomes.

Web demo

There is a work in progress WebAssembly demo available at:

https://badel2.github.io/slime_seed_finder/

Also, a biome viewer (like Amidst but without structures): https://badel2.github.io/slime_seed_finder/biomes.html

And a tool to find the seed of a saved world: https://badel2.github.io/slime_seed_finder/anvil.html

Local instalation

To build this project you need to install the Rust programming language. Follow the instructions on https://rustup.rs Then, run the following commands

git clone https://github.com/badel2/slime_seed_finder
cd slime_seed_finder
cargo install --path . --features="main" -f

Now you should have the slime_seed_finder executable in your $PATH.

To update to the latest version:

git pull origin master
cargo install --path . --features="main" -f

Usage

slime_seed_finder find -i seedinfo.json -o seeds.json

Run slime_seed_finder --help for full details about the usage, and slime_seed_finder <subcommand> --help for detailed help about a subcommand.

The SeedInfo is a JSON with information about the world that can be useful to find the seed.

If you don't have a list of slime chunks and want to try this program, use the generate option to generate slime chunks. You can choose a numerical seed, or leave it blank to generate a random seed. You can specify how many slime chunks to generate with --num-slime-chunks (the default is 0):

# Random seed
slime_seed_finder generate -o seedinfo_random_seed.json --num-slime-chunks 40
# Seed 1234
slime_seed_finder generate -s 1234 -o seedinfo_1234.json --num-slime-chunks 40
# Finding seed 1234
slime_seed_finder find -i seedinfo_1234.json -o 1234_and_some_more.json

If you already have a list of possible 48-bit seeds, put them in a file as a JSON array:

slime_seed_finder find --candidate-seeds candidates.json -i seedinfo.json

Anvil

Anvil is the name of the format used to store chunk data. The anvil subcommand allows you to work directly on Minecraft saves:

RUST_LOG=debug slime_seed_finder anvil --input-dir=survival/region/ --mc-version="1.7"

This will use various techniques to find the world seed.

As this is an experimental feature, please only use it on backup worlds, and never on a world that is currently open by Minecraft, as it may corrupt it.

See also: web version

Recover the seed of an Alpha world

This tool can also find the seed using only dungeons. This can be useful to recover the seed of a corrupted alpha world. Check out this guide .

extend48

To convert 48-bit seeds into 64-bit seeds (by assuming that the seed was generated using Java Random nextLong), put the 48-bit seeds in candidates.json as a JSON array and run the extend48 subcommand. For example, to extend the seeds 1 and 2:

echo '[1, 2]' > candidates.json
slime_seed_finder extend48 -i candidates.json

Output:

[
  8897424013823836161,
  -651896046061879294
]

It will become more clear if we convert those seeds to hexadecimal:

0x7b7a000000000001
0xf6f4000000000002

In this case each 48-bit seed has 1 corresponding 64-bit seed, but it can be 0, 1 or 2 seeds. This has the implications that the only way to create a new Minecraft world with seed 1 or 2 is to manually set the seed to that number.

Theory

PRNG internals

Slime Chunks

Building WebAssembly demo

In order to locally test the web demos:

# Install wasm_bindgen
cargo install -f wasm-bindgen-cli
# And run this after each change
./ci/build_demo.sh

You need to run a local web server at the static/ dir. You can use the provided server.py file, which starts a server at http://localhost:8000

cd static
python3 server.py

Experimental WAPM support

This package is published on WAPM:

https://wapm.io/package/badel2/slime_seed_finder

Most of the functionalities of the CLI version should work, albeit slower. Also, it doesn't support multithreading so using it to bruteforce seeds will be slower than the web demo. And I will probably forget to update it.

Use this shell, you can use drag and drop to upload files, and use the "download" command to get the files back:

https://webassembly.sh/?run-command=wapm%20install%20badel2/slime_seed_finder

For example, you can use it to render biome maps:

$ slime_seed_finder rendermap --seed=1234
Saved image to biome_map_1.14_1234_0_0_1024x640.png
$ download biome_map_1.14_1234_0_0_1024x640.png
Downloading the file...

See also

https://github.com/pruby/slime-seed - A project with the same goal and similar optimizations