Multi-signature wallet concept in Blockchain / Solidity

Introduction

A multi-signature wallet needs more than one person to approve a transaction. This makes it safer because no single person can spend money alone.

When a group of friends want to share control of a digital wallet.

For a company to require multiple managers to approve payments.

To protect funds by needing several approvals before sending money.

When you want extra security so one lost key does not lose all funds.

Syntax

Blockchain / Solidity

multiSigWallet = {
  owners: [address1, address2, address3],
  requiredSignatures: 2,
  transactions: [],
  submitTransaction(tx) { ... },
  confirmTransaction(txId, owner) { ... },
  executeTransaction(txId) { ... }
}

owners is the list of people who can approve transactions.

requiredSignatures is how many approvals are needed to send money.

Examples

This wallet needs 2 out of 3 owners to approve a transaction.

Blockchain / Solidity

owners = ['Alice', 'Bob', 'Carol']
requiredSignatures = 2

This wallet needs both owners to approve before sending money.

Blockchain / Solidity

owners = ['Dave', 'Eve']
requiredSignatures = 2

Sample Program

This program creates a multi-signature wallet with three owners. It submits a transaction, then owners confirm it. The transaction only executes after enough owners approve.

Blockchain / Solidity

class MultiSigWallet:
    def __init__(self, owners, required_signatures):
        self.owners = owners
        self.required_signatures = required_signatures
        self.transactions = {}
        self.confirmations = {}
        self.tx_count = 0

    def submit_transaction(self, tx):
        tx_id = self.tx_count
        self.transactions[tx_id] = tx
        self.confirmations[tx_id] = set()
        self.tx_count += 1
        print(f"Transaction {tx_id} submitted: {tx}")
        return tx_id

    def confirm_transaction(self, tx_id, owner):
        if owner not in self.owners:
            print(f"{owner} is not an owner.")
            return
        if tx_id not in self.transactions:
            print(f"Transaction {tx_id} does not exist.")
            return
        self.confirmations[tx_id].add(owner)
        print(f"{owner} confirmed transaction {tx_id}.")

    def execute_transaction(self, tx_id):
        if tx_id not in self.transactions:
            print(f"Transaction {tx_id} does not exist.")
            return
        if len(self.confirmations[tx_id]) >= self.required_signatures:
            print(f"Transaction {tx_id} executed: {self.transactions[tx_id]}")
            del self.transactions[tx_id]
            del self.confirmations[tx_id]
        else:
            print(f"Transaction {tx_id} needs more confirmations.")

# Example usage
owners = ['Alice', 'Bob', 'Carol']
wallet = MultiSigWallet(owners, 2)
tx_id = wallet.submit_transaction('Send 10 coins to Dave')
wallet.confirm_transaction(tx_id, 'Alice')
wallet.execute_transaction(tx_id)  # Not enough confirmations
wallet.confirm_transaction(tx_id, 'Bob')
wallet.execute_transaction(tx_id)  # Now it executes

Important Notes

Multi-signature wallets increase security by requiring multiple approvals.

Each owner has a unique key to sign transactions.

Without enough confirmations, transactions cannot be executed.

Summary

Multi-signature wallets need several people to approve transactions.

This protects funds from being spent by one person alone.

They are useful for groups or companies managing shared money.