Its main function is to protect the UK from terrorism and cyber attacks, but now GCHQ is set for its second foray into the rather less dangerous world of puzzle books. The country's top code breakers have created a new set of brainteasers to mark the intelligence agency's centenary year in 2019. And to celebrate its upcoming release, the organisation have posted a teaser on Twitter using emojis. The GCHQ posted a teaser on Twitter yesterday about the release of its new book using emojis. The answer to the difficult puzzle is expected to be given later today.