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

# Secure Relayer

> Handling private keys securely

# Secure Relayer Setup

Bayex uses a relayer system to subsidize gas for user onboarding or specific interactions. Security is paramount when handling the relayer's private keys.

## The Problem

Storing private keys on the client-side (e.g., in `.env` exposed to the browser) is a critical security vulnerability.

## The Solution: External Relayer Service

We utilize the **Polymarket Relayer** (`relayer-v2`) for executing gasless transactions. This removes the need for managing a hot wallet on your own backend for standard operations.

### Architecture

1. **Client Signature**: The user signs a typed data structure (EIP-712) in their browser. This signature grants permission for the specific action (e.g., `CTWrapper.wrap`).
2. **Relayer Submission**: The frontend sends this signature and the transaction payload to the Relayer API.
3. **Execution**: The Relayer verifies the payload, pays the MATIC gas fees, and submits the transaction to the Polygon network.

### API Endpoint

**Production:** `https://relayer-v2.polymarket.com/`

### Implementation Flow

Instead of sending transactions directly via `window.ethereum`:

1. Construct the meta-transaction payload.
2. Request user signature via `eth_signTypedData_v4`.
3. POST the payload to the Relayer.

```typescript theme={null}
// Example Payload Construction
const payload = {
  to: contractAddress,
  data: encodedFunctionData,
  signature: userSignature,
  // ... other relayer specific fields
};

await axios.post("https://relayer-v2.polymarket.com/transactions", payload);
```