The last thing you'd expect a spy agency to do is open itself up to the public, and yet Britain's Government Communications Headquarters (GCHQ) wants as many people as possible to learn a thing or two about cryptography. The spy agency, the equivalent (and a close partner) of the United States' National Security Agency, recently released Cryptoy: an Android app that teaches kids the basics of making and breaking codes, then lets them try to make something unbreakable themselves.

Cryptoy showed up on the Google Play Store last week, and while it comes from the British government, you can download and use it on an Android device in any region. (Not all devices are compatible with the app.) The program aims to teach four common methods of encryption: shift, substitution, Vigenère and Enigma.

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As the app's name suggests, this app is all about having fun rather than providing hardcore encryption know-how. The app will teach you how to create various ciphers, rate the strength of each one, show you a bit of the British history behind each encryption technique and let you share your creations with friends.

Although an app like this might seem like a natural recruiting tool for the GCHQ, the app's permissions are actually extremely mild, and there does not appear to be any way for the government to track users through it. The GCHQ probably hopes to raise awareness about what it does and get talented candidates interested tangentially, rather than use the app as a recruitment drive.,

The app is free and (as far as we can tell) safe, so if cryptography sounds like something you'd like to try, there's no reason to pass it up. Then, when one of your friends claims that your texts are indecipherable, you can show him or her just how much further you can go.