What is CrypTool 1?

CrypTool 1 (CT1) is an open-source Windows program for cryptography and cryptanalysis. It’s the most widespread e-learning software of its kind.

What is CrypTool 2?

CrypTool 2 (CT2) is an open-source program offering an innovative visual programming GUI to experiment with cryptographic procedures and to animate their workflow.

What is JCrypTool?

JCrypTool (JCT) is an open-source e-learning platform, allowing to experiment comprehensively with cryptography on Linux, macOS, and Windows.

What is CrypTool-Online?

CrypTool-Online (CTO) runs in a browser and provides a variety of encryption and cryptanalysis methods including illustrated examples and tools like password generator and password meter.

What is MysteryTwister C3?

MysteryTwister C3 (MTC3) is an international Crypto Cipher Contest offering a broad variety of challenges, a moderated forum, and an ongoing hall-of-fame.


While you can learn a lot about classic encryption methods and their weaknesses under the menu item Ciphers, you here have the chance to encrypt a text in hex with the modern AES encryption method. Currently, this method is being regarded as safe – provided a "good" key is used.

You can have the Password Generator provide you with a safe password. On this site, you can also learn about what a "good" password is and how to remember a seemingly complicated password without a problem.

Try beating the computer at the Taxman game and prove your mathematical skills by getting to the top of the high score.

Many more cryptographic functions, some of them in colorful visualizations, are contained in the downloadable versions of CrypTool – an overview of these more than 300 functions can be found here.