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monero-multisig

trying my hand at m of n, will add more robust web eventually

Features

• Flexible M-of-N configurations — 2-of-3, 3-of-5, or any valid threshold
• Multi-round key exchange — handles the full Monero multisig setup protocol
• Transaction co-signing — build, partially sign, and submit multisig transactions
• Balance synchronization — export/import partial key images between co-signers
• Daemon RPC integration — communicates directly with monerod via JSON-RPC
• Persistent state — wallet setup progress is saved locally between sessions

Architecture

┌──────────────────────────────────────────────────┐
│                    CLI (clap)                     │
│  create-wallet · exchange-keys · sign-tx · ...   │
├──────────────┬──────────────────┬────────────────┤
│   wallet.rs  │  transaction.rs  │   config.rs    │
│              │                  │                 │
│  Key setup   │  Build, sign,    │  RPC client,   │
│  & exchange  │  & submit txs    │  settings       │
├──────────────┴──────────────────┴────────────────┤
│              Monero Daemon (monerod)              │
│                 JSON-RPC API                      │
└──────────────────────────────────────────────────┘

Module Overview

Module	Purpose
main.rs	CLI argument parsing and command dispatch
wallet.rs	Multisig wallet creation, key exchange rounds, state persistence
transaction.rs	Unsigned tx building, partial signing, submission, balance sync
config.rs	Daemon RPC connection, JSON config loading, JSON-RPC client

Prerequisites

• Rust 1.70+ (curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh)
• Monero daemon (monerod) running with RPC enabled
• Monero wallet RPC (monero-wallet-rpc) for each participant

Build

git clone https://github.com/melonmelonz/monero-multisig.git
cd monero-multisig
cargo build --release

The binary will be at target/release/monero-multisig.

Usage

1. Create wallets (each participant)

# Participant A
monero-multisig create-wallet --threshold 2 --participants 3 --label "shared-fund"
# → outputs multisig info string A

# Participant B (on their machine)
monero-multisig create-wallet --threshold 2 --participants 3 --label "shared-fund"
# → outputs multisig info string B

# Participant C
monero-multisig create-wallet --threshold 2 --participants 3 --label "shared-fund"
# → outputs multisig info string C

2. Exchange keys

Each participant collects the info strings from all others and runs:

# Participant A exchanges with B and C's info
monero-multisig exchange-keys --info "<B_info>" "<C_info>"

For M > 2, multiple rounds are required — the tool will prompt you to share updated info strings after each round.

3. Synchronize balances

Before building a transaction, all participants must share partial key images:

# Each participant exports their info
monero-multisig export-info
# → share the output with all co-signers

# Each participant imports the others' info
monero-multisig import-info --info "<peer1_info>" "<peer2_info>"

4. Build and sign a transaction

# One participant builds the unsigned transaction
monero-multisig build-tx --address "4..." --amount 1000000000000 --priority 1
# → outputs multisig tx set data

# Each required co-signer signs it
monero-multisig sign-tx --tx-data "<tx_set_hex>"
# → outputs updated tx set with their signature applied

Check balance

monero-multisig balance

5. Submit

Once the threshold number of signatures is collected:

monero-multisig submit-tx --tx-data "<fully_signed_tx_hex>"
# → Transaction submitted! Hash: abc123...

Configuration

Pass a JSON config file with --config:

{
  "network": "stagenet",
  "daemon": {
    "host": "127.0.0.1",
    "port": 38081,
    "tls": false
  },
  "data_dir": "/home/user/.monero-multisig"
}

Or use CLI flags for quick overrides:

monero-multisig --daemon-host node.example.com --daemon-port 18081 create-wallet ...

Multisig Protocol Overview

Monero multisig works through a multi-step protocol:

1. Prepare — Each participant generates their multisig key material
2. Key Exchange — Participants share info strings in one or more rounds:
   • 2-of-N: single make_multisig round
   • M-of-N (M > 2): (M − 1) rounds of exchange_multisig_keys
3. Sync — Before transacting, participants exchange partial key images so each wallet can compute the correct balance
4. Sign — A transaction is built by one party and passed to M co-signers
5. Submit — The fully signed transaction is broadcast to the network

Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/my-feature)
3. Commit your changes (git commit -am 'Add my feature')
4. Push to the branch (git push origin feature/my-feature)
5. Open a pull request

License

MIT — see LICENSE for details.