Secret!

Discover the fascinating world of secrets!

Why do we love secrets? How do we keep them? And how are they revealed? The interactive exhibition “Secret!” invites visitors to explore these questions.
The success story of modern, mathematically based cryptography began soon after the Second World War. Without these new methods and asymmetric cryptography, today's internet applications, electronic payment systems, mobile communications, digital tax returns and general data protection would not be feasible, and in some cases even unimaginable.
But secrets are also very important in everyday life: They range from simple hiding places, such as a key under the doormat, to private diaries and agreements, contracts or wills that need to be protected from unauthorized persons.

From February 14 to December 14, 2025, you can discover the mechanisms behind secrets at numerous interactive exhibits, test your own creativity and gain surprising insights.

• Decode words using the rotating wheels and find out how one of the oldest encryption methods works.
• Learn about historical encryption machines and understand their significance in history.
• Discover some of the basics of modern cryptography and how it protects us in everyday life.
• From fortune cookies to treasure chests – discover the beauty of little secrets.
• Match well-known phrases with the right pictures.
• Solve an exciting encryption puzzle.

The exhibition was designed by the Mathematikum Gießen and will delight adults and children from age 8 and above. 
Guided tours of the MAINS take place on each of the opening days at 3 p.m.; a registration is not necessary.