This fun and educational app teaches you about the mysterious world of cryptography. It will help you to understand ciphers and key, and enable you to create encrypted messages that you can share with your friends.

You can learn about four encryption techniques:
  • Shift
  • Substitution
  • Vigenère
  • Enigma
You can build your own messages interactively using these techniques, as well as learning the history behind their use.
Once you’ve created a message, you can share it with your friends and see if they can decrypt it… it’s up to you how much help or information you give them!

Developed by students for students

The Cryptoy app was designed by Science, Technology, Engineering and Maths (STEM) students on an industrial placement at GCHQ.
It was created as part of a project to demonstrate encryption techniques at the Cheltenham Science Festival, and has since been demonstrated at other educational events.
Many teachers told us they wanted to use Cryptoy in their schools to teach about codes and ciphers, so we decided to make it available as a free app for anyone to download.

Find out more about the app

Download Cryptoy onto your Android tablet

Please note that the IOS version of Cryptoy, suitable for use on iPads, is coming soon. Contact us if you would like to know when it becomes available.
To download the app onto your Android tablet go to Google Play.
Cryptoy is purely an educational app, and doesn’t require any permissions to access personal data or enhancements to be made to your device when installing.

The legal stuff

See the Terms & Conditions for the GCHQ website, and our Disclaimer for your use of the Cryptoy app.


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Scotby, Carlisle

t 01228 631681