Cryptoy - explore the fascinating world of cryptography

Last Updated: 01 Jun 2016
This fun and educational app teaches you about the mysterious world of cryptography.


Cryptoy Promo Screen

Cryptoy 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!


Cryptoy In Use


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

Cryptoy is an educational application made for, and making use of, the Android operating system, which is covered under the Apache Licence, Version 2.0. Other software used that is also covered under the Apache Licence, Version 2.0 is TwoWayView and CircularList Adapter.

In using the Cryptoy app, each person who does so (a "User") thereby acknowledges and agrees that their use of the Cryptoy app is entirely at their own risk, and that it is provided on an "as is" and "as available" basis, without any warranty or representation of any kind, by Her Majesty's Government ("HMG") and with no obligation on HMG to further develop or maintain it.

Any use of the Cryptoy app, and of any material obtained through use of it, is at the User's sole discretion and risk, and HMG shall not be liable for any direct or indirect loss or damage (of whatever nature) incurred by a User or any other person, arising from or in connection with such use. As far as the law allows, HMG expressly disclaims all warranties and conditions of any kind, whether express or implied, including (but not limited to) any concerning the fitness for purpose of the Cryptoy app.

The app has been tested on the following platforms only:

  • Google Nexus 10 (2013)
  • Google Nexus 7 (2012)
  • Google Nexus 7 (2013)

The app has been tested on versions 4.1.2 through 4.4.2 of the Android operating system only.

The Cryptoy app has been developed under the Science, Technology, Engineering and Mathematics (STEM) initiative by HMG sponsored students at GCHQ, and is protected by UK Crown Copyright.