# Signing Orders

> 📘 Note
>
> As a measure to counter replay attacks, we are adding the `timestamp` field for order signing. Presently, this field is optional.
>
> Starting from **21 August 2023 00:00 UTC**, the timestamp field will become mandatory, ensuring enhanced security and preventing potential replay attacks.

To create an order, a signature needs to be generated. This signature allows for the gasless trading experience in Aevo. The signature generation used by Aevo follows the guideline laid out in the EIP-712 (<https://eips.ethereum.org/EIPS/eip-712>) . This signing method is widely used and supported in most wallets.

> 🚧 Important!
>
> The signature generated for order submission is **different** from the signature for authentication.

## Method

***

* Signature is generated by signing the `Order` payload using the account's `Signing Key`
* `Signing Key` is generated during Enable Trading.

## Example

***

```python
from random import randint
from eip712_structs import EIP712Struct, Address, Uint, Boolean, make_domain
from web3 import Web3
from eth_account import Account

# Generate Salt
salt = randint(0, 10**6)

# Limit price and amount is in 6 decimal places
decimals = 10**6
limit_price = int(100 * decimals)  # Limit price of $100
amount = int(2 * decimals)  # Size of 2 contracts

# Current timestamp in UNIX seconds
timestamp = 1690434000 

# instrument_id from /options-chain
instrument = 1

class Order(EIP712Struct):
    maker = Address()
    isBuy = Boolean()
    limitPrice = Uint(256)
    amount = Uint(256)
    salt = Uint(256)
    instrument = Uint(256)
    timestamp = Uint(256)

order_struct = Order(maker="your_address", # The wallet's main address
                    isBuy=True, # True if buy, False if sell
                    limitPrice=limit_price,
                    amount=amount,
                    salt=salt,
                    instrument=instrument,
                    timestamp=timestamp)

# Get bytes
domain = make_domain(name="Aevo Mainnet", version="1", chainId=1)
# Testnet Domain
# domain = make_domain(name='Aevo Testnet', version='1', chainId=11155111)
signable_bytes = Web3.keccak(order_struct.signable_bytes(domain=domain))

# Sign with key
key = "your_signing_key"
signature = Account._sign_hash(signable_bytes, key).signature.hex()
```

```javascript
// Get signing keys, and sign message
const signer = new ethers.Wallet(signingKey);

const orderMessage = {
  maker: "your_wallet_address,
  isBuy: true,  // true if buy, false if sell
  instrument: "ETH-24AUG22-1850-C",
  
  // Limit price is in 6 decimal places. 
  // Eg. $10.00 = "10000000"
  limitPrice: ethers.utils.parseUnits(10, 6).toString(),

  // This is the number of contracts
  amount: 10,
    
  // Timestamp in UNIX seconds
	timestamp: 1690434000, 

  // Random number
  salt: Math.floor(Math.random() * 100000).toString(),
}

// Get the order signature
const orderSignature = await signer._signTypedData(
  {
    name: "Aevo Mainnet",
    version: "1",
    chainId: 1,
  },
  { 
    Order: [
      { name: "maker", type: "address" },
      { name: "isBuy", type: "bool" },
      { name: "limitPrice", type: "uint256" },
      { name: "amount", type: "uint256" },
      { name: "salt", type: "uint256" },
      { name: "instrument", type: "uint256" },
      { name: "timestamp", type:"uint256" },
    ]
  },
  orderMessage
);
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.aevo.xyz/api-reference/signing-orders.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.