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.

About CrypTool 2

CrypTool 2 is the modern successor of CrypTool 1, the well-known e-learning platform for cryptography and cryptanalysis.

Modern Plug’n’Play Interface / Visual Programming


CrypTool 2 provides a graphical user interface for visual programming. So workflows can be visualized and controlled to enable intuitive manipulation and interaction of cryptographic functions.

The vector-oriented GUI is based on the Windows Presentation Foundation (WPF) and gives users the ability to scale the current view at will.

CrypTool 2 follows the Microsoft Office 2007 User Interface Design Guideline, providing a consistent and rich user experience.

Visualization of Algorithms

Visualisation of Algorithms

The same component used for visual workflow programming can also visualize its inner operation. This makes it handy for the user to comprehend all the details of a cryptographic algorithm while seeing the bigger picture of how this algorithm may be used in a real-life scenario.

Comprehensive Cryptanalysis Functions

Frequency Test

CrypTool 2 provides a variety of cryptanalytical tools to analyze or even break classical and modern ciphers. With the current version you can, for instance, apply a ciphertext-only attack on an Enigma-encrypted ciphertext. Plenty of other cryptanalysis functions are also available, such as performing frequency tests to find n-grams and assessing the length of a codeword used for a polyalphabetic cipher (such as the Vigenère cipher).

Integrated Online Help

Integrated Online-Help

It has always been essential for every version of CrypTool to come with thorough documentation about its functions. Whenever the user presses F1 on their keyboard, corresponding information about the function currently selected appears. The online help comprises instructions about using the function as well as a theoretical background and references for further reading on the topic.


CrypTool always was and always will be an open source project. CrypTool 2 is licensed under the Apache Open Source Licence 2.0.

Anyone interested in adding functionality is welcome to do so. CrypTool 2 is based on the latest .NET Framework (currently .NET 4.7.2) and has a pure-plugin architecture, which makes it very easy for new volunteers to develop additional functions. A new developer can fully concentrate on the functional aspects of his or her plugin and must merely implement some rather simple interfaces to integrate in the core system.

Please see the documentation page for access to the source code and for joining the developer wiki..

In Wikipedia you can find a description of the whole open-source project CrypTool.