chela

chela splits one secret - a crypto wallet's recovery phrase, or any short password - into a set of paper cards, so that any M of the N cards rebuild it and any fewer reveal nothing at all. Make five cards and require three: two can be lost or destroyed and you can still recover, while anyone who finds one or two learns nothing.

It is built for inheritance and disaster recovery. Hand the cards to family or trusted friends; the secret comes back only when enough of them bring their cards together. Each card is a short list of ordinary words, and a card recovers from those words alone

• no account, no server, nothing kept online.

The method is Shamir's Secret Sharing, the standard approach for exactly this problem. chela implements it - and everything it needs, the field arithmetic, BIP-39, the checksums - from scratch in this repository, with no outside dependencies, so every line can be read and checked. SPEC.md explains how it works, in plain language and in full detail.

I was handed a card and need to recover a secret

You don't need to be technical, and you don't need to install anything.

Take your time. The paper cards in your hand are the only thing that can recover the secret, and they don't expire. If you need to come back tomorrow, they will still work tomorrow.

1. Find any computer with a web browser - Windows, Mac, or Linux, anything from the last decade.
2. Download the recovery program. On the latest release, under Assets, click the file whose name ends in -web.html. Save it to your Desktop or Downloads.
3. Open it. Double-click the file; it opens in your browser as chela's main screen.
4. Click "Recover from shares" and follow the wizard. It asks for one card at a time, then shows the recovered secret.
5. You need a minimum number of cards. The card itself says how many: look for the "M of N" on the front (for example "3 of 5" means any 3 of the 5 cards).

Step by step, with screenshots: RECOVERY.md. And if every copy of chela ever vanished, you can still recover by hand with pen and paper: MANUAL_RECOVERY.md.

Privacy: chela runs entirely inside your browser. Nothing is sent over the internet. To be extra careful, turn off Wi-Fi before you start - it works the same offline.

I want to make a backup

Pick two numbers: how many cards to make (N) and how many it should take to recover (M). "5 cards, any 3" is a common choice. Then:

1. Download the -web.html file from the latest release and open it in your browser (the same file used for recovery).
2. Choose to split a secret, enter your wallet phrase or password, set M and N, and add a name and the cardholders if you want them printed.
3. Print the cards (Print → Save as PDF works well), give one to each person, and store them somewhere safe. Keep the whole card: the words are what recover the secret, and the printed label is there to help.

Prefer a terminal? The interactive wizard and the scriptable CLI are under Build from source.

What is printed on a card

CHELA-<RSID>-<x>-<M>-<N>-<W>
word1 word2 ... wordW

The words on the second line are the secret in split form, and a card recovers from its words alone. The top line just restates the same details for people to read, and it is cross-checked against the words. One card on its own reveals nothing about the secret - not even what kind of secret it is. The exact format is in SPEC.md.

Understanding and checking chela

chela is meant to be a tool you can trust without taking anyone's word for it.

• SPEC.md - what chela does and exactly how a card is built, from first principles and precise enough to reimplement in another language.
• AUDITORS.md - a guided walk through the cryptographic code, file by file.
• MANUAL_RECOVERY.md - recover a secret by hand, on paper, with no computer at all.
• AGENTS.md - for pointing an AI assistant at the repository to check that it is sound and well packaged.

Build from source

git clone https://github.com/SecretSplitKit/Chela.git
cd chela
cargo build --release --workspace
cargo test --workspace

Path	What it is
target/release/chela	Interactive wizard (terminal)
target/release/chela-cli	Scriptable command-line tool
target/release/chela-bundle	Builds the standalone chela.html

Wizard - ./target/release/chela splits a seed or password, recovers, or quits. The split wizard ends by offering a print-ready HTML backup; the recover wizard stops at the threshold, asks for confirmation before showing the secret, and clears the screen on exit.

CLI:

# Split a 24-word seed (+ optional passphrase) into 5 cards, any 3 to recover.
./target/release/chela-cli split --mnemonic "abandon abandon ... art" \
  --passphrase "optional passphrase" -m 3 -n 5 --paper backup.html > shares.txt

# Split arbitrary text.
./target/release/chela-cli split --text "correct horse battery staple" -m 2 -n 4 > shares.txt

# Recover from any threshold of cards.
./target/release/chela-cli recover < shares.txt

Standalone browser file - ./target/release/chela-bundle chela.html writes one self-contained HTML file. Open it in any modern browser; no install, no network.

Verifying a release

Every release artifact is signed with minisign and built reproducibly: rebuilding a given source tag on the same target and toolchain yields byte-identical binaries, which the release workflow checks with a two-pass build.

SHA256SUMS and SHA256SUMS.minisig are attached to every release. Save the public key below as chela.pub, then:

minisign -V -p chela.pub -m SHA256SUMS
sha256sum -c SHA256SUMS

Public key

untrusted comment: minisign public key DDD078AB7F7BE629
RWQp5nt/q3jQ3XBn/Ni5bQNj6MehmwvQTYgdBQ9zxTTgc4+qyJfazk9x

Reproduce a release locally

git checkout <tag>
SOURCE_DATE_EPOCH=$(git log -1 --pretty=%ct) \
  RUSTFLAGS="-C link-arg=-Wl,--build-id=none" \
  cargo build --release --locked
sha256sum target/release/chela target/release/chela-cli target/release/chela-bundle

Compare against the release's SHA256SUMS. The RUSTFLAGS above are for Linux; macOS uses -Wl,-no_uuid and Windows MSVC uses /Brepro. The release workflow (.github/workflows/release.yml) is the authoritative recipe.

License

Dual-licensed at your option:

• Apache 2.0 (LICENSE-APACHE)
• MIT (LICENSE-MIT)