Gallery: Challenge yourself to some of the GCHQ's toughest puzzles

The GCHQ Puzzle Book

The Government Communications Headquarters in the UK is home to some of the smartest cryptanalysts, puzzle crackers, and hackers in the world. It just published a book full of puzzles to challenge, frustrate, and test readers with some of the most mind-bending tests of skill in the world.

What follows is seven selections from this book of over 200 puzzles. Some are easy, some not so much. The first TechRepublic reader to contact me with the correct answers to all seven questions will win my copy of the GCHQ Puzzle Book.

In addition is one tough puzzle that doesn't have instructions--i Spy. Part of the puzzle is actually figuring out what you're supposed to be doing.

You'll also find the latest challenge to come out of the GCHQ itself. You don't need to answer this question to be eligible to win the book--it's just there as the ultimate test of your puzzle solving mettle.

Good luck!

All images and puzzles courtesy of CGHQ/Penguin Books

Image: GCHQ/Penguin Books

By Brandon Vigliarolo

Brandon writes about apps and software for TechRepublic. He's an award-winning feature writer who previously worked as an IT professional and served as an MP in the US Army.