Delve into the world of cryptography with Cryptoy!

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

You'll learn about four encryption techniques:

- Shift
- Substitution
- Vigenère
- Enigma

You'll have a fun and interactive way of building your own messages using each technique, 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 of information you give them!

Cryptoy is brought to you by STEM students sponsored by GCHQ, the UK intelligence agency responsible for providing Signals Intelligence (SIGINT) to Her Majesty's Government. We are also the UK's National Technical Authority for Information Assurance, and provide guidance on the use of technology and encryption.

For more information about inspiring young people in Science, Technology, Engineering and Mathematics (STEM) go to

For more information about the work of GCHQ visit

Disclaimer - The Cryptoy App is an educational application made for, and making use of, the Android operating system, which is covered under the Apache License, Version 2.0. Other software used that is also covered under the Apache License, Version 2.0 is TwoWayView and CircularListAdapter.

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 thier own risk, and that it is provided on an "an 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, and is protected by UK Crown Copyright.
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Additional Information

December 11, 2014
Current Version
Requires Android
4.1 and up
Content Rating
Warning – content has not yet been rated. Unrated apps may potentially contain content appropriate for mature audiences only.
Offered By
Government Communication Headquarters
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