The Government Communications Headquarters (GCHQ) has released an app aimed at introducing secondary school students to the basic principles of cryptography, enabling them to create encoded messages which can be shared on social media and then deciphered by their friends.

The app, Cryptoy, was designed by students on placement at the GCHQ for the Cheltenham Science Festival, and has been used at several outreach events since. The GCHQ received interest from multiple teachers who wanted to use the app as a teaching aid, and so has elected to release it as a free Android app, with an iOS version planned for 2015.

The GCHQ hopes the app will encourage the uptake of STEM (science, technology, engineering and maths) subjects in schools, and help build a knowledge base of cyber security skills in the UKs young adults.

“Building maths and cyber skills in the younger generation is essential for maintaining the cyber security of the UK and growing a vibrant digital economy,” said Robert Hannigan, director of the GCHQ. “That is why I am keen for GCHQ to give something back through its work with school and universities.”

The agency has faced controversy in recent years after Edward Snowdens revelations that the security and signals intelligence agency was attempting to collect all online and telephone data in the UK, but has also seen interest in its activities in World War II driven by the release of The Imitation Game, a film dealing with the work it carried out at Bletchley Park in breaking the German Enigma codes.