How to Sign an OKEx POST API Request?

Below is a Python implementation for signing OKEx API requests, covering both GET and POST methods:

Python Implementation for API Signing

import hmac
import base64
import requests
import datetime
import json

# Configuration (replace with your credentials)
API_KEY = "your_api_key"
API_SECRET = "your_api_secret"
API_PASSPHRASE = "your_passphrase"
BASE_URL = "https://www.okx.com"

def get_timestamp():
    """Generate ISO 8601 formatted UTC timestamp"""
    now = datetime.datetime.utcnow()
    return now.isoformat("T", "milliseconds") + "Z"

def generate_signature(timestamp, method, endpoint, body, secret_key):
    """Generate HMAC SHA256 signature"""
    message = str(timestamp) + method.upper() + endpoint
    if body:
        message += json.dumps(body)
    mac = hmac.new(
        bytes(secret_key, "utf-8"),
        bytes(message, "utf-8"),
        digestmod="sha256"
    )
    return base64.b64encode(mac.digest()).decode("utf-8")

def get_headers(method, endpoint, body=None):
    """Generate request headers"""
    timestamp = get_timestamp()
    return {
        "OK-ACCESS-KEY": API_KEY,
        "OK-ACCESS-SIGN": generate_signature(timestamp, method, endpoint, body, API_SECRET),
        "OK-ACCESS-TIMESTAMP": timestamp,
        "OK-ACCESS-PASSPHRASE": API_PASSPHRASE,
        "Content-Type": "application/json"
    }

def api_request(method, endpoint, body=None):
    """Execute authenticated API request"""
    url = BASE_URL + endpoint
    headers = get_headers(method, endpoint, body)
    
    if method == "GET":
        response = requests.get(url, headers=headers)
    elif method == "POST":
        response = requests.post(url, headers=headers, json=body)
    
    return response.json()

Common Use Cases

GET Request Example (Account Balance)

balance = api_request("GET", "/api/v5/account/balance")
print(balance)

POST Request Example (Place Order)

order_data = {
    "instId": "BTC-USDT",
    "tdMode": "cash",
    "side": "buy",
    "ordType": "market",
    "sz": "1"
}
order_result = api_request("POST", "/api/v5/trade/order", order_data)
print(order_result)

Troubleshooting Invalid Signatures

When receiving {'msg': 'Invalid Sign', 'code': '50113'} errors:

Timestamp Verification:
- Ensure your system clock is synchronized with NTP
- Timestamp must be within ±30 seconds of OKEx server time
Body Formatting:
- For POST requests, include the body in signature calculation
- Use consistent JSON serialization (no extra spaces or line breaks)
Endpoint Accuracy:
- Verify the endpoint path matches exactly with API documentation
- Include version prefix (e.g., /api/v5/)

👉 For more API examples, visit OKEx's official documentation

FAQ Section