> For the complete documentation index, see [llms.txt](https://devs.truebit.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://devs.truebit.io/architecture/audit-layer.md).

# Audit Layer

**Truebit Verify uses a blockchain-backed Audit Layer to underpin its security model and enforce its core protocols**. The Audit Layer performs several key functions:

## **Node Registry Smart Contract**

**NodeRegistry Address:** `0x1e1802b2807FfE7fF22dCa24E8ff7d30a3a8150c`

Node Registration is set up on the blockchain. **It maintains a transparent list of all active Truebit Verify Nodes.** Registered nodes can participate in the computation of a task solution if selected.

When a node is registered on the Node Registration Ledger, its unique Ethereum (ETH) address is added to the NodeRegistry smart contract's storage; similarly before the shutdown, it needs to de-register to ensure a graceful shutdown.

The NodeRegistry is an EVM-compatible smart contract and it manages the list of active nodes within the Node Registration Ledger. Each position on the list contains one registered Node Address.

## Task Registry Smart Contract

**TaskRegistry Address:** `0x6825142A0e85dDB3cBf872a26eE2beefaedbc465`

Task Registration is set up on the blockchain. **It keeps a clear list of all registered and verifiable** **tasks.** Once registered, tasks can be executed directly using the Truebit API's execute endpoint.

The TaskRegistry is an EVM-compatible smart contract that includes all necessary methods for managing namespaces and tasks, allowing anyone to register their deployed tasks.

## Task Authorization Smart Contract

**TaskAuthorization Address:** `0x6da8eE7DF16BD92eb71F314f4b701C6c5b0b2721`

Task Authorization is set up on the blockchain, **maintaining a clear list of all authorized addresses that can execute tasks within a namespace**. It also keeps a list of registered API\_KEY hashes, allowing other users to execute tasks while making the user who registered the API\_KEY responsible for the task execution payment.

The TaskRegistry is an EVM-compatible smart contract that includes all necessary methods for managing accesses over a namespace.