Using PEM encoded X.509 certificates in Java

PEM is a well know file format when it comes to certificates. And when using Kubernetes (or OpenShift in my case) it is so easy to re-use the internal CA for some tasks.

Except when it comes to Java. As Java does only use JKS (its Java-only, binary keystore) or PKCS12 for keys and certificates. So Google offers you a bunch of tutorials on how to convert PEM encoded certificates to JKS or PKCS12 so that Java can consume that. But that may be ugly in a lot of situations. Doing that manually once if fine. But adding this to e.g. a pod, becomes a lengthy YAML init container setup, which seems unnecessary to me.

But Java does allow the use of security providers, which may extend the security system. However searching the net, I couldn’t find anything which would provider a PEM based KeyStore. Maybe that was simply due to the fact that the over “convert PEM to …” tutorials spammed the search results.

So I went along and simply created my own provider. For my own use case, which is using the OpenShift service CA certificate. It only took a few minutes to do the actual implementation as reading a PEM file is no mystery.

In case you need to use a PEM encoded X.509 certificate in Java, you now can either re-encode that with `openssl` on the command line or simply drop on this provider and use `PEM` as the KeyStore type:


And then:

KeyStore keyStore = KeyStore.getInstance("PEM");

For more information see: ctron/pem-keystore at GitHub

If you know some other provider which supports this, please let me know and I would be happy to switch as this is only a scratch to my itch 🙂 On the other hand if this is useful to you, then please let me know. There are still a few things missing, like keys and Java 9+ support. But maybe you want to submit a pull request for that 😀

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