Monthly Archives: May 2018

2 posts

Using PKCS #1 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. 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 :D

Update: I did release an update of this provider. Version 2.0 has support for keys and CA bundles.

Eclipse Kura on the Intel UP² with CentOS

Intel UP² In the past I was testing modifications to Kura with a Raspberry Pi 3 and Fedora for ARM. But I got a nice little Intel UP² just recently, and so I decided to perform my next Kura tests, with the modifications to the Apache Camel runtime in Kura, on this nice board. Creating a new device profile for Kura using CentOS 7 and the Intel UP² looked like a good idea anyway.

At the time of writing, the PR for merging the device profile into Kura is still pending (PR #2093). But my hope is that this will be merged before Kura 4 comes out.

Build your own Kura image

But it is possible to try this out right now by using the preview branch (preview/intel_up2_1) on my forked repository: ctron/kura.

The following commands use the kura-build container. For more information about building Kura with this container see: and

So for the moment you will need to build this image yourself. But if you have Docker installed, then it only needs a few minutes to create your own build of Kura:

docker run -v /path/to/output:/output -ti ctron/kura-build -r ctron/kura -b preview/intel_up2_1 -- -Pintel-up2-centos-7

Where /path/to/output must be replaced with a local directory where the resulting output should be placed. If you are running Docker with SElinux enabled, then you might need to append :z to the volume:

docker run -v /path/to/output:/output:z -ti ctron/kura-build -r ctron/kura -b preview/intel_up2_1 -- -Pintel-up2-centos-7

As you might guess, it is also possible to build other branches and repositories of Kura in the same way. That docker image only ensures that all the necessary build dependencies are present when executing the build.

If you are running on Linux and do have all the dependencies installed locally. Then of course there is no need to run through Docker, you can simply call the build-kura script directly:

./build-kura preview/intel_up2_1 -r ctron/kura -b preview/intel_up2_1 -- -Pintel-up2-centos-7

Setting up CentOS 7

This is rather simple step, you simply need to download CentOS from (the Minimal ISO is just fine). Copy the ISO to a USB stick ( On a Linux-ish system this should work like (where /dev/sdX is the USB stick, all data on this stick will be lost!):

sudo dd if=CentOS-7-x86_64-Minimal-1804.iso of=/dev/sdX bs=8M status=progress oflag=direct

Rebooting your UP with the USB stick attached, this should reboot into the CentOS installer from where you can perform a standard installation.

After the installation is finished and you booted into CentOS, you will need to enable EPEL, as Kura requires some extra components (like wireless-tools and hostapd). You can do this by executing:

sudo yum install epel-release

You might also want to install a more recent kernel into CentOS. All the core things works with the default CentOS kernel. However some things like support for the GPIO support is still missing in the default CentOS kernel. But the mainline kernel from ELRepo can easily be installed:

rpm --import
rpm -Uvh
yum --enablerepo=elrepo-kernel install kernel-ml

For more information check e.g.:

Installing Kura on the Intel UP²

Copy the RPM you just created from the build process over to the UP, e.g. by:

scp kura-build-output/2018XXXX-YYYY/kura-intel-up2-centos-7*.rpm user@my-up:

And then on the device run:

yum install kura-*.rpm

This will install the Kura package as well as any required dependencies. After the installation has completed, reboot the machine and navigate your web browser to “http://my-up”, using the credentials “admin” / “admin”.

More information