A real world example of digital signature checking

In this post we will see exactly how we can check if a SSL certificate hasn’t been tampered with. We will use https://google.com as an example and we’re manually going to check that the certificate’s digital signature is valid. Other important steps such as traversing the entire chain is beyond the scope of this simple […]

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Containerising the development environment

One of the nice things about docker is that we can use all kinds of software without cluttering up our local machine. I really like the ability to have the development environment running in a container. Here is an example where we: Get a Node.js development environment with all required tools and packages Allow remote […]

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Docker on Raspbian: cgroup not supported on this system

Are you running Docker on Raspbian and getting the error: cgroups: memory cgroup not supported on this system Best solution is to add cgroup_memory=1 in /boot/cmdline.txt and reboot. PLease note, for future releases of Raspbian you will need the following instead: Alternatively, you can downgrade to an earlier docker version:

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Returning a collection of objects from a PowerShell function

If you’re writing a function that returns a collection then don’t forget to include the comma operator in the return statement. If you forget it your function will work correctly when the collection contains multiple objects, but fails when it contains 1 object. Take the following buggy example: If you execute this code when $myarray […]

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Starting a process in PowerShell with dynamic command-line parameters

Starting a command-line process from PowerShell is very easy. A simple java -jar helloworld.jar works just fine. However when I’m starting nodes in my Selenium Grid I need to dynamically create a different number of parameters. The following code will fail because the various strings wont be correctly mapped to the usual argv[] input parameters […]

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How to generate self signed certificates

Sometimes you need a self-signed certificate for the purpose of testing websites or digitally signing files such as PDFs. Your PDF software will probably ask you for a .pfx file. You can generate these on Windows, Mac or linux On Windows On windows, with Visual Studio, you can use the makecert utility: Linux and Mac […]

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