British surveillance agency GCHQ has launched an app teaching children to understand “basic encryption techniques”, despite its director having criticised technology firms for making more advanced tools available to their users.

Cryptoy is a free app for Android tablets, with an iPad version expected to launch in 2015. It teaches children about four encryption techniques – shift, substitution, Vigenère and Enigma – as well as the history behind their use.

“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,” explains its listing on the Google Play store.

The app is aimed at Key Stage 4 students in the UK – those aged between 14 and 16 years old – and was originally developed by students on a year’s placement at GCHQ, for the Cheltenham Science Festival.

Its release is part of the British government’s drive to encourage more children to study STEM subjects – science, technology, engineering and maths – at GCSE level and beyond.

“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. That is why I am keen for GCHQ to give something back through its work with school and universities,” said the agency’s director Robert Hannigan, as the app launched.

“In particular, the Cryptoy app is a colourful, interactive way for students and their teachers to explore the fascinating world of cryptography. The app was developed by GCHQ’s industrial placement students and trialled at a number of science fairs. I hope it will inspire further study of this key topic, which has played such an important part in our past and is an invaluable part of our future.”

Hannigan recently sparked controversy with his first public intervention in the surveillance debate since taking over as GCHQ director, when he attacked US technology companies as “the command and control networks of choice” for terrorists when they make techniques for encrypting and/or anonymising communications available.

Facebook recently made it easier for users of the Tor anonymising service to access the social network by launching a .onion address, while messaging app WhatsApp is introducing end-to-end encryption, and Apple has made encryption a part of its iMessage service.

Encouraging children to learn about the history of cryptography – Enigma included – while pushing back against technology companies’ moves to introduce end-to-end encryption is not necessarily a contradiction.

However, one side-effect of Cryptoy may be to stimulate students to ask questions not just about historic encryption, but its modern variants: why technology companies are introducing them, and the role played in that process by agencies like GCHQ.

Cryptoy does not request permission to Android devices’ cameras, location or contacts information. In fact, the only permission its Google Play entry lists is “Other” – a category that according to Google may include “custom settings provided by your device manufacturer or application-specific permissions”.

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