GCHQ Visitors

Last week, we welcomed two GCHQ employees who taught us about the history of coding (from the Roman times, to more recently, World War II) and how coding has significantly shaped British history.

We were taught about steganography (the practice of hiding secret messages in plain sight). We learnt that people, through history, have used steganography. One way this was done was by shaving someone’s head and writing a secret message before waiting for their hair to grow back! Once their hair had grown enough, they would send the message to the recipient and have their hair shaved off again so the message could be read! More recently, we were told, coders have hid messages within pixelated pictures.

We also learnt about transposition. We were tasked with wrapping a slip of paper around wooden sticks (with different-sized diameters). We then wrote a secret message before passing this onto another group who had a different-sized stick. The code didn’t work! We were told that the recipient of the message would need the same ‘key’. We were shown Caesar’s Ciphers (a coding tool) and encrypted messages before passing them to another group who needed to decode the code.

After this, we learnt more about coding during World War II. We learnt about the various coding machines used, including: Enigma, Lorenz and the MK2. We also learnt how the team at Bletchley Park used the Bombe machine and Colossus computer to crack German encrypted messages.

Finally, we were given the opportunity to explore various WWII artefacts.