Using a self-signed cert in Tomcat

A pretty common scenario is to set up a test server and client and getting a cert from a third party can be expensive and time-consuming. You can, of course, sign your own cert. Be aware that this will restrict others unless they make an exception in their browser when connecting to your site. It is not reccomended for production server, but is awfully handy for testing.

Why do this? The OAuth exchange happens in two stages. First, the user comes in with a browser. At that point the user must accept an exception if your Tomcat has a self-signed cert. Once the user log in, a redirect is made to the client, which fires up its own SSL connection and has only a basic set of certs available. Anything else (the analog of the exception in the browser) must be manually configured. The practical problem with that is that Java has a very bad way to do it, either by restricting the JVM to using your cert only or requiring you to manufacture your own version of a trust store. This is the reason that there is a way to set this in the client configuration.

Creating a self-signed cert

It is pretty easy to create on of these. The easiest path is probably to use the Java keytool and issue the following command:

    keytool -genkey -keyalg RSA -alias selfsigned -keystore localhost-keystore.jks -storepass password -validity 365 -keysize 2048

where you set the name of the keystore and the password (with the -storepass flag). The validity refers to the number of days, so this will create a cert that is valid for a year. You would then need to fill in some prompts that will be given to you. This is all quite straightforward. These are all for making the CN (Common Name). One tip is to just hit return and use the same password for the keystore as for the cert. You can then check that it worked by issuing

    keytool -list -storepass password -keystore localhost-keystore.jks

Setting the keystore in Tomcat.

I assume you are using just Tomcat and have created a JKS (Java Keystore) that contains your cert for your server. Add an <ssl> block to your client configuration that points to this store, so if you have something like this in the Tomcat server.xml file:

    <Connector port="9443"
               clientAuth="false" sslProtocol="TLS >

It is also possible to set a trust store here. Normally the truststore (set of trusted certs) that is the default one shipped with your version of Java is more than sufficient.

Using the certs with your OA4MP client

In your client configuration you would just point to this same keystore:

<client name="your-client-config-name"
      <!-- other stuff!!-->
     <ssl useJavaTrustStore="true">
   <!-- more stuff -->

That should do it. I prefer to put passwords in a CDATA tag since that means you can use special characters and not have to worry about them. There is an older way to do this in OA4MP that is still supported which is inferior because the password is an attribute and this prevented many passwords from being used. You can also use a PKCS12 store if you have that. In that case, the type is PKCS12.

Last modified 11/20/19.
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