> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mls.onchainden.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Smart Contracts

> Open-source, audited smart contracts power the on-chain security layer of Multi-Layer Security Wallet.

The smart contracts are the final layer of defense in the [three-layer security architecture](/enterprise-security/security-layers). They enforce your organization's policies directly on-chain, blocking any transaction that does not meet policy requirements, even if every off-chain system is compromised.

## Open source

The complete smart contract codebase is open source and available on GitHub:

<Card title="OnChainDen/mls-contracts" icon="github" href="https://github.com/OnChainDen/mls-contracts" horizontal>
  Source code, tests, deployment scripts, and technical documentation
</Card>

Anyone can read the code, verify the deployed contracts against the source, and independently review the security properties of the system.

## Technical documentation

Extensive, in-depth technical documentation lives alongside the code in the repository. If you want to understand exactly how the contracts work, start with the [repository README](https://github.com/OnChainDen/mls-contracts#readme), then explore the detailed deep-dives:

| Topic                                                                                                             | Description                                                           |
| ----------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------- |
| [Merkle Tree Architecture](https://github.com/OnChainDen/mls-contracts/blob/main/docs/MERKLETREE_ARCHITECTURE.md) | How policies are stored as a Merkle tree and verified with proofs     |
| [Guardian Protection](https://github.com/OnChainDen/mls-contracts/blob/main/docs/GUARDIAN_PROTECTION.md)          | Guardian architecture, `SafeExecutorModule`, and update flows         |
| [Signatures](https://github.com/OnChainDen/mls-contracts/blob/main/docs/SIGNATURES.md)                            | Signature encoding formats, EIP-712, nonces, and signed message types |
| [Disaster Recovery](https://github.com/OnChainDen/mls-contracts/blob/main/docs/DISASTER_RECOVERY.md)              | Guardian recovery and transaction recovery mechanisms                 |
| [Deployment](https://github.com/OnChainDen/mls-contracts/blob/main/docs/DEPLOYMENT.md)                            | Deployment instructions and configuration                             |

## Security audits and deployments

<CardGroup cols={2}>
  <Card title="Security Audits" icon="shield-check" href="/smart-contracts/audits">
    Independent third-party audit reports from Certora and yAudit
  </Card>

  <Card title="Deployments" icon="network-wired" href="/smart-contracts/deployments">
    Supported networks and deployed contract addresses
  </Card>
</CardGroup>