HTTPS With Undertow

This guide will help you generate a certificate and configure Undertow to use it for HTTPS.

The project

To go through this guide, you need a Web project based on the Undertow embedded Web server. If you don’t have one, invoke the SeedStack generator to create a web project type:

mvn -U org.seedstack:seedstack-maven-plugin:generate

A self-signed certificate

In this section, you are going to start the process by generating a self-signed certificate.

Generate the certificate

We are going to use the Java keytool program (locate in the JDK bin folder) to generate a keystore containing a 2048 bits self-signed certificate and its key pair. Go into the project directory and type:

keytool -genkey -alias ssl -keyalg RSA -keysize 2048 -dname "CN=myserver.mycompany.com,OU=IT,O=My company,L=Paris,C=FR,email=contact@email.com" -keystore master.jks -storepass changeMe -keypass changeMe

Configure the keystore and SSL

Now edit the application.yaml file of your project. Add the following section to configure the master keystore:

crypto:
  keystores:
    master:
      path: master.jks
      password: changeMe
  ssl:
    keyPassword: changeMe

This declares:

• A keystore named master, based on the file we generated before.
• The password used by SSL to read the key from the keystore.

Enable HTTPS

In the application.yaml file, add the following section:

web:
  server:
    https: true

This will enable HTTP on port 8080, HTTPS on port 8443 and will automatically redirect any HTTP access to HTTPS.

Try it!

Launch the Web application:

mvn seedstack:run

And point your browser to https://localhost:8443.

A trusted certificate

In this section, you are going to ask a trusted «Certificate Authority» (CA) to sign your initial certificate to replace your self-signed one.

Create a CSR

To obtain a trusted certificate, you need to create a «Certificate Signing Request» (CSR):

keytool -certreq -alias ssl -keystore master.jks -file request.csr

This CSR will have to be submitted to the CA of your choice, which will return the signed certificate to you.

Import the CA certificates in the keystore

To be able to import the signed certificate in the keystore, you must first import the CA certificate(s) in the keystore:

keytool -import -trustcacerts -alias root_ca -file root_ca.crt -keystore master.jks -storepass changeMe -keypass changeMe

Import the signed certificate

At last, import the signed certificate in the keystore under the same alias as your self-signed certificate to overwrite it:

keytool -import -alias ssl -file signed_cert.cer -keystore master.jks -storepass changeMe -keypass changeMe

Try it!

After deploying the application on an URL matching the CN of your certificate, you can point your browser to the CN. In our (fake) example, it is:

https://myserver.mycompany.com

Mutual authentication

This section deals about establishing a mutual authentication between the server and the clients. It’s useful when you need to guarantee your client identity from their certificate.

Create a truststore to validate client certificates

To be able to validate the chain of trust, you have to import the certification authority (CA) certificate(s) into a truststore:

keytool -import -trustcacerts -alias root_ca -file root_ca.crt -keystore truststore.jks -storepass changeMe -keypass changeMe

Configure the truststore

Now edit the application.yaml file of your project. Add the following section to configure the truststore:

crypto:
  truststore:
    path: truststore.jks
    password: changeMe

Configure SSL to require a client certificate

If you want to go beyond HTTPS and require HTTPS clients to send their own certificate, set the following configuration:

crypto:
  ssl:
    clientAuthMode: REQUIRED

Optional: use the client certificate for authentication

If you want to use the client certificate as the subject identity you will need to have the following dependency in your project:

<dependency>
    <groupId>org.seedstack.seed</groupId>
    <artifactId>seed-web-security</artifactId>
    <version>3.13.0</version>
</dependency>

dependencies {
    compile("org.seedstack.seed:seed-web-security:3.13.0")
}

Then configure the security subsystem to use the certificate for authentication and authorization purposes:

security:
  realms: X509CertificateRealm

To extract the certificate from the HTTP request, add the cert filter on the necessary URL patterns:

security:
  web:
    urls:
      -
        pattern: "/**"
        filters: cert

You can inject the SecuritySupport interface to do additional checks on the subject:

package org.generated.project.interfaces.rest;

import javax.inject.Inject;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import org.seedstack.seed.security.SecuritySupport;

@Path("hello")
public class HelloResource {
    @Inject
    private SecuritySupport securitySupport;

    @GET
    public String hello() {
        String id = securitySupport.getIdentityPrincipal().getPrincipal().toString();
        return "Hello " + id + "!";
    }
}

Troubleshooting

Setting up a working SSL handshake can be tricky, so if you encounter any problem you can switch the Java SSL debugging on with the -Djavax.net.debug=all system property. Example with the run goal:

mvn -Djavax.net.debug=all seedstack:run