When I was a teacher, a question I was constantly asked by curious students was, “Can you teach us how to hack?” Turning this idea on its head, and teaching the techniques behind some of our most important national cyber security measures, is an excellent way of motivating students to do good. This is why the Raspberry Pi Foundation and GCHQ have been working together to bring you exciting new resources!

### More computing power with the OctaPi

You may have read about GCHQ’s OctaPi computer in Issue 58 of the MagPi. The OctaPi is a cluster computer joining together the power of eight Raspberry Pis (i.e. 32 cores) in a distributed computer system to execute computations much faster than a single Pi could perform them.

We have created a brand-new tutorial on how to **build your own OctaPi** at home. Don’t have eight Raspberry Pis lying around? Build a TetraPi (4) or a HexaPi (6) instead! You could even build the OctaPi with Pi Zero Ws if you wish. You will be able to run any programs you like on your new cluster computer, as it has all the software of a regular Pi, but is more powerful.

### Understanding cryptography

You probably use public key cryptography online every day without even realising it, but now you can use your OctaPi to understand exactly how it keeps your data safe. Our new **OctaPi: public key cryptography** resource walks you through the invention of this type of encryption (spoiler: Diffie and Hellman weren’t the first to invent it!). In it, you’ll also learn how a public key is created, whether a brute force attack using the OctaPi could be used to find out a public key, and you will be able to try breaking an encryption example yourself.

These resources are some our most advanced educational materials yet, and fit in with the “Maker” level of the Raspberry Pi Foundation Digital Making Curriculum. The projects are ideal for older students, perhaps those looking to study Computer Science at university. And there’s more to come: we have two other OctaPi resources in the pipeline to make use of the OctaPi’s full capabilities, so watch this space!