Simple multisig contract with Fift

This information is very low-level. It could be hard for newcomers and designed for advanced people who want to understand Fift. The use of Fift is not required in everyday tasks.

Overview

This tutorial helps you learn how to deploy your multisig contract. Recall that a $(n, k)$-multisig contract is a multi-signature wallet with $n$ private key holders, which accepts requests to send messages if the request (a.k.a. order, query) collects at least $k$ holder’s signatures.

Based on the original multisig contract code and updates by akifoq:

• Original TON Blockchain multisig-code.fc
• akifoq/multisig with Fift libraries to work with multisig.

Prefer videos over text?

Watch this if you are new to multi-signature wallets: What is Multisig Technology? (video)

What you’ll learn

• How to create and customize a simple multisig wallet.
• How to deploy a multisig wallet using Lite client.
• How to sign a request and send it in a message to the blockchain.

Set up your environment

Before we begin our journey, check and prepare your environment.

• Install func, fift, lite-client binaries, and fiftlib from the latest GitHub release.
• Clone the repository and open its directory in CLI.

git clone https://github.com/akifoq/multisig.git
cd ./multisig

Get started

1. Compile the code to Fift.
2. Prepare multisig owner’s keys.
3. Deploy your contract.
4. Interact with the deployed multisig wallet in the blockchain.

Compile the contract

Compile the contract to Fift with:

func -o multisig-code.fif -SPA stdlib.fc multisig-code.fc

Prepare multisig owner’s keys

Create participant’s keys

To create a key, you need to run:

fift -s new-key.fif $KEY_NAME$

• Where KEY_NAME is the file name where the private key will be written.

For example:

fift -s new-key.fif multisig_key

We’ll receive a multisig_key.pk file with the private key inside.

Collect public keys

Also, the script will issue a public key in the format:

Public key = Pub5XqPLwPgP8rtryoUDg2sadfuGjkT4DLRaVeIr08lb8CB5HW

Anything after Public key = needs to be saved somewhere!

Let’s store it in a file called keys.txt. It’s important to have one public key per line.

Deploy your contract

Deploy via lite-client

After creating all the keys, you need to collect the public keys into a text file, keys.txt.

For example:

PubExXl3MdwPVuffxRXkhKN1avcGYrm6QgJfsqdf4dUc0an7/IA
PubH821csswh8R1uO9rLYyP1laCpYWxhNkx+epOkqwdWXgzY4

After that, you need to run:

fift -s new-multisig.fif 0 $WALLET_ID$ wallet $KEYS_COUNT$ ./keys.txt

• $WALLET_ID$: the wallet number assigned to the current key. It is recommended that each new wallet with the same key use a unique $WALLET_ID$.
• $KEYS_COUNT$: the number of keys needed for confirmation, usually equal to the number of public keys.

Wallet ID explained

It is possible to create many wallets with the same keys (Alice key, Bob key). What should we do if Alice and Bob already share a wallet? That’s why $WALLET_ID$ is crucial here.

The script will output something like:

new wallet address = 0:4bbb2660097db5c72dd5e9086115010f0f8c8501e0b8fef1fe318d9de5d0e501

(Saving address to file wallet.addr)

Non-bounceable address (for init): 0QBLuyZgCX21xy3V6QhhFQEPD4yFAeC4_vH-MY2d5dDlAbel

Bounceable address (for later access): kQBLuyZgCX21xy3V6QhhFQEPD4yFAeC4_vH-MY2d5dDlAepg

(Saved wallet creating query to file wallet-create.boc)

Keep the bounceable address — this is the wallet address we will be using.

If you have a “public key must be 48 characters long” error, please make sure your keys.txt uses Unix-style line endings (LF). For example, line endings can be changed via Sublime Text.

Activate your contract

You need to send some TON to the newly generated wallet. For example, 0.5 TON. You can send testnet coins via @testgiver_ton_bot.

After that, run lite-client:

lite-client -C global.config.json

Where to get global.config.json?

You can get a fresh config file global.config.json for Mainnet or Testnet.

After starting Lite client, it’s best to run the time command in the lite-client console to make sure the connection was successful:

time

Okay, Lite client works!

After that, you need to deploy the wallet. Run the command:

sendfile ./wallet-create.boc

After that, the wallet will be ready to work within a minute.

Interact with a multisig wallet

Create a request

First, you need to create a message request:

fift -s create-msg.fif $ADDRESS$ $AMOUNT$ $MESSAGE$

• $ADDRESS$ - address where to send coins.
• $AMOUNT$ - number of coins (in TON).
• $MESSAGE$ - the file name for the compiled message.

For example:

fift -s create-msg.fif EQApAj3rEnJJSxEjEHVKrH3QZgto_MQMOmk8l72azaXlY1zB 0.1 message

Use the -C comment attribute to add a comment for your transaction. To get more information, run the create-msg.fif file without parameters.

Choose a wallet

Next, you need to choose a wallet to send coins from:

fift -s create-order.fif $WALLET_ID$ $MESSAGE$ -t $AWAIT_TIME$

Where:

• $WALLET_ID$ — ID of the wallet backed by this multisig contract.
• $AWAIT_TIME$ — time in seconds the smart contract will await signatures from the multisig wallet owners for the request.
• $MESSAGE$ — name of the message BoC file created in the previous step.

The request expires if $AWAIT_TIME$ elapses before the request is signed. As usual, $AWAIT_TIME$ equals a couple of hours (7200 seconds).

For example:

fift -s create-order.fif 0 message -t 7200

The resulting file is saved as order.boc.

order.boc must be shared with key holders; they must sign it.

Sign your part

To sign, run:

fift -s add-signature.fif $KEY$ $KEY_INDEX$

• $KEY$ - file name containing the private key to sign, without extension.
• $KEY_INDEX$ - index of the given key in keys.txt (zero-based).

For example, for our multisig_key.pk file:

fift -s add-signature.fif multisig_key 0

Create a message

After everyone has signed the order, it needs to be turned into a message for the wallet and signed again with the following command:

fift -s create-external-message.fif wallet $KEY$ $KEY_INDEX$

In this case, only one signature from a wallet owner is enough. The idea is that you can’t attack a contract with invalid signatures.

For example:

fift -s create-external-message.fif wallet multisig_key 0

Send the signed message to the TON blockchain

After that, start lite-client again:

lite-client -C global.config.json

And finally, we want to send our sign! Just run:

sendfile wallet-query.boc

If everyone else signed the request, it will be completed!

You did it!

See also

• Multisignature wallet v2