ARE YOU AS SMART as cryptographers for one of the world’s most secretive spy agencies? The spymasters at Government Communications Headquarters, or GCHQ, recently posted a brain teaser for the public, but internally the British eavesdropping agency for years has been testing the mental prowess of its employees with the Kryptos Kristmas Kwiz. This holiday season, The Intercept is posting one of the mind-bending quizzes — normally not available to the public — from the archive of documents provided by Edward Snowden. The winner of GCHQ’s game got a Kryptos mug. The Intercept can only offer bragging rights.

We will post the answers on New Year’s Day.