How to Secure a Spring Boot API Using API Key and Secret Authentication?

How can I secure my Spring Boot API using API keys and secrets instead of standard authentication?

Securing your Spring Boot API with API keys and secrets is a common practice for limiting access to authorized clients without implementing traditional username and password authentication. This approach is essential when you want to provide a simple access mechanism for third-party applications.

import org.springframework.web.filter.OncePerRequestFilter;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class ApiKeyAuthFilter extends OncePerRequestFilter {
    private static final String API_KEY_HEADER = "X-API-KEY";
    private static final String API_SECRET_HEADER = "X-API-SECRET";
    private final String validApiKey = "your_api_key";
    private final String validApiSecret = "your_api_secret";

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
            throws ServletException, IOException {
        String apiKey = request.getHeader(API_KEY_HEADER);
        String apiSecret = request.getHeader(API_SECRET_HEADER);

        if (!validApiKey.equals(apiKey) || !validApiSecret.equals(apiSecret)) {
            response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Unauthorized");
            return;
        }

        filterChain.doFilter(request, response);
    }
} 

// To register the filter, use:
@Override
protected void configure(HttpSecurity http) throws Exception {
    http.addFilterBefore(new ApiKeyAuthFilter(), UsernamePasswordAuthenticationFilter.class);
}

Solutions

• 1. **Generate API Keys and Secrets**: Start by generating unique API keys and secrets for each client. Avoid sharing the same key among multiple clients.
• 2. **Create a Filter**: Implement a filter in your Spring Boot application that intercepts incoming requests to check for the presence of a valid API key and secret in the headers.
• 3. **Use Spring Security**: Leverage Spring Security to configure security settings. You can create a basic configuration that checks for the API key and secret before processing any requests.
• 4. **Custom Exception Handling**: Handle unauthorized access attempts gracefully by returning specific HTTP status codes (like 401 - Unauthorized) if the API credentials are missing or invalid.
• 5. **Documentation for Clients**: Provide clear documentation to your clients on how to use the API key and secret to access your endpoints.

Mistake: Not validating API keys and secrets properly, allowing unauthorized access.

Solution: Ensure that you strictly check both the API key and secret and return a 401 error if they do not match.

Mistake: Using static keys for all clients.

Solution: Generate unique keys for each client to enhance security and prevent cross-access.