Solana Multisig Program

A secure, fully functional Multi-Signature (Multisig) smart contract built on Solana using the Anchor framework. This program allows a group of designated owners to jointly manage funds and execute transactions based on a configurable threshold of approvals.

📋 Table of Contents

• Features
• Architecture
• Prerequisites
• Getting Started
• Testing
• Program Instructions
• Error Codes
• Security Considerations
• License

✨ Features

• Dynamic Ownership: Support for up to 10 distinct owners per multisig instance.
• Customizable Thresholds: Require any number of approvals ($M$ of $N$) to execute a transaction.
• Secure Execution: Transactions are executed directly from the Multisig PDA, ensuring funds are strictly managed by the program.
• Deterministic PDAs: Both the Multisig and its Transactions are derived using deterministic seeds for easy discovery.
• Comprehensive Edge-Case Handling: Protects against duplicate signers, overflow attacks, and unauthorized execution.

🏗 Architecture

State Accounts

1. MultisigAccount

   • Tracks the list of owners (up to 10).
   • Stores the required threshold of signatures.
   • Maintains a transaction_index (nonce) to ensure unique PDAs for every proposed transaction.

2. TransactionAccount

   • Stores the destination address (to).
   • Stores the amount of lamports to transfer (amount).
   • Tracks approvals via a boolean vector (signers).
   • Maintains execution state (executed) to prevent double-spending.

🛠 Prerequisites

Ensure you have the following installed before getting started:

• Rust (latest stable)
• Solana CLI (v1.16+ recommended)
• Anchor CLI (v0.29+)
• Node.js & Yarn (or npm/bun)

🚀 Getting Started

1. Clone the repository

   git clone https://github.com/Enmilo-dev/sol-multisig
   cd sol-multisig

2. Install dependencies

   npm install
   # or bun install / yarn install

3. Build the Anchor program

   anchor build

4. Sync program ID Update the program ID in Anchor.toml and programs/multisig/src/lib.rs with the newly generated key from target/deploy/multisig-keypair.json.

   anchor keys sync

🧪 Testing

The repository includes a comprehensive Mocha/Chai test suite validating both the happy paths and security edge cases (e.g., threshold limits, duplicate authorizations).

To run the local test validator and the full suite:

anchor test

📖 Program Instructions

create_multisig

Initializes a new MultisigAccount PDA.

• Parameters: owners (Array of Pubkeys), threshold (u8).
• Validation: Ensures 2 <= threshold <= owners.len() <= 10. Checks for duplicate owners.

create_transaction

Proposes a new transfer of SOL from the multisig.

• Parameters: amount (u64 in lamports), recipient (Pubkey).
• Behavior: Derives a new PDA for the transaction, sets the creator as the first signer automatically, and increments the multisig's transaction index.

approve

Appends a signature to a pending transaction.

• Behavior: Flips the signer's index in the TransactionAccount.signers array to true.
• Validation: Ensures the transaction hasn't been executed and the signer hasn't already approved.

execute_transaction

Executes the transaction and transfers funds to the recipient.

• Behavior: Validates that the number of approvals meets the required threshold. If valid, transfers lamports from the Multisig PDA to the recipient PDA and marks the transaction as executed.

🛑 Error Codes

Code	Name	Description
6000	OwnersCountExceeded	Maximum of 10 owners allowed
6001	OwnersCountNotMet	Minimum of 2 owners required
6002	DuplicateOwner	The owners array contains duplicates
6003	InvalidOwner	The signer is not an authorized owner
6004	ThresholdExceeded	Threshold cannot exceed the number of owners
6005	ThresholdNotMet	Not enough approvals to execute transaction
6006	InvalidAmount	Transaction amount must be greater than 0
6007	TransactionAlreadyExecuted	This transaction has already been processed
6008	AlreadyApproved	This owner has already approved this transaction
6009	Overflow	Math overflow error

🛡 Security Considerations

• Rent Exemption: Standard Solana rent logic applies. When verifying execution balances in tests, remember to account for the base rent-exemption lamports held by initialized PDAs.
• Double Spend Protection: Transactions use a boolean executed flag which strictly prevents replay attacks.
• Signer Verification: All instructions verify that the executing account signed the transaction via Anchor's Signer<'info> wrapper.

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.