How can I securely implement user-based authentication for the completions API without exposing my API key?

Based on the OpenAI API documentation, the completions API supports only API key authentication. In other words, there isn’t an alternative method (such as OAuth or similar user-specific flows) built into the API that allows each end user to authenticate with their own credentials.

Recommended Approach

Given this limitation, here’s the recommended approach:

• Backend Proxy:
  Route your API requests through your own backend server. Your server will hold your API key securely (loaded from an environment variable or key management service) and can handle the actual call to the OpenAI API. You can then implement user management (login, sessions, etc.) on your server.

• User-Based Attribution:
  Manage user accounts and track usage on your backend. While the API calls are made using your API key, your server can attribute requests and responses to individual users based on your own authentication system.

This ensures that the API key is never exposed in client-side code, and you maintain control over user authentication while still accessing the completions API securely.

Example Flow

1. User Authentication:
   Your app authenticates users using your preferred method (e.g., username/password, OAuth via another provider, etc.).

2. Proxy Request:
   When a user makes a request, your frontend sends the request to your backend along with their session token.

3. Server Processing:
   Your backend verifies the user session, prepares the request for the completions API, and adds the API key in the Authorization header.

4. Call to OpenAI:
   Your server makes the call to the OpenAI API and returns the result to the frontend.

Code Example

Below is a simplified example in Node.js using Express:

JAVASCRIPTCopied
const express = require('express');
const axios = require('axios');
require('dotenv').config();

const app = express();
app.use(express.json());

app.post('/api/complete', async (req, res) => {
  // Example: Verify user session here
  // If valid, process the user's request:

  const prompt = req.body.prompt;
  
  try {
    const response = await axios.post('https://api.openai.com/v1/completions', {
      prompt: prompt,
      max_tokens: 50,
      model: 'text-davinci-003'
    }, {
      headers: {
        'Authorization': `Bearer ${process.env.OPENAI_API_KEY}`,
        'Content-Type': 'application/json'
      }
    });

    res.json(response.data);
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});

This pattern lets you securely use a single API key while still offering a user authentication and tracking system within your application.

Conclusion

There is no native, user-specific authentication mechanism for the completions API beyond using API keys. Instead, using a backend proxy is the best practice to handle both user authentication and keeping your API key secure while attributing individual requests to the proper user.

If you have any follow-up questions or need further clarification on working with the API, feel free to ask!