Securing Spring Boot API with API key and secret

Create a filter that grabs what ever header(s) you’re using for authentication.

import org.springframework.security.web.authentication.preauth.AbstractPreAuthenticatedProcessingFilter;

public class APIKeyAuthFilter extends AbstractPreAuthenticatedProcessingFilter {

    private String principalRequestHeader;

    public APIKeyAuthFilter(String principalRequestHeader) {
        this.principalRequestHeader = principalRequestHeader;
    }

    @Override
    protected Object getPreAuthenticatedPrincipal(HttpServletRequest request) {
        return request.getHeader(principalRequestHeader);
    }

    @Override
    protected Object getPreAuthenticatedCredentials(HttpServletRequest request) {
        return "N/A";
    }

}

Configure the filter in your Web Security config.

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.BadCredentialsException;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.config.http.SessionCreationPolicy;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;

@Configuration
@EnableWebSecurity
@Order(1)
public class APISecurityConfig extends WebSecurityConfigurerAdapter {

    @Value("${yourapp.http.auth-token-header-name}")
    private String principalRequestHeader;

    @Value("${yourapp.http.auth-token}")
    private String principalRequestValue;

    @Override
    protected void configure(HttpSecurity httpSecurity) throws Exception {
        APIKeyAuthFilter filter = new APIKeyAuthFilter(principalRequestHeader);
        filter.setAuthenticationManager(new AuthenticationManager() {

            @Override
            public Authentication authenticate(Authentication authentication) throws AuthenticationException {
                String principal = (String) authentication.getPrincipal();
                if (!principalRequestValue.equals(principal))
                {
                    throw new BadCredentialsException("The API key was not found or not the expected value.");
                }
                authentication.setAuthenticated(true);
                return authentication;
            }
        });
        httpSecurity.
            antMatcher("/api/**").
            csrf().disable().
            sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS).
            and().addFilter(filter).authorizeRequests().anyRequest().authenticated();
    }

}