How do I handle authentication for AI tool calls?
Secure Your API Keys
When your AI application calls external APIs (e.g., weather, database), you need credentials. Never embed API keys in prompts or client-side code. Instead, keep them in environment variables or a secrets manager on your server.
Your server acts as a proxy: it receives the tool call from the AI, adds the necessary authentication headers, and forwards the request to the external service. This keeps keys hidden from users.
- Use environment variables or secret managers
- Never expose keys in client-side JavaScript
- Rotate keys periodically
- Use least-privilege scopes for each key
User Authentication and Authorization
If tools act on behalf of a user (e.g., accessing their calendar), you need user authentication. Use OAuth 2.0 to obtain access tokens with specific scopes. The AI should not handle user credentials directly; instead, your app manages the OAuth flow.
When the AI requests a tool call, your server checks if the user has granted the necessary permissions. If not, return an error or prompt for authorization. This prevents unauthorized access.
Validate and Sanitize Inputs
Even with authentication, validate all inputs from the AI to prevent injection attacks. For example, if a tool queries a database, use parameterized queries. Also, restrict tools to only the operations the user is allowed to perform.
Consider rate limiting and logging to detect abuse. Authentication is not just about keys; it's about ensuring the right access controls are in place.
Common mistakes
- Putting API keys directly in the prompt or client-side code, exposing them to users.
- Skipping user-level authorization and letting the AI access any data without permission checks.
- Not validating inputs from the AI, leading to injection vulnerabilities.