CrypTool is a free, open-source e-learning application, used worldwide in the implementation and analysis of cryptographic algorithms. It supports both contemporary teaching methods at schools and universities as well as awareness training for employees and civil servants. The program can be downloaded here.

The current version offers the following highlights:

• Numerous classic and modern cryptographic algorithms (encryption and decryption, key generation, secure passwords, authentication, secure protocols, etc.)
• Visualization of several algorithms (Caesar, Enigma, RSA, Diffie-Hellman, digital signatures, AES, etc.)
• Cryptanalysis of several algorithms (Vigenère, RSA, AES, etc.)
• Cryptanalytical measurement methods (entropy, n-grams, autocorrelation, etc.)
• Related auxiliary methods (primality tests, factorization, base64 encoding, etc.)
• Number theory tutorial
• Comprehensive online help
• Accompanying script with additional information about cryptology
• And plenty more!

Originally designed as an internal business application for information security training, CrypTool has since developed into an important open-source project in the field of cryptology. Over 50 volunteer developers worldwide have contributed to the program.

Since spring 2008, the CrypTool project has been operating the Crypto Portal for Teachers. The portal is currently only available in German, but is intended to act as a platform for teachers to share teaching materials and related links concerning cryptology.

Since spring 2009, the CrypTool project has also been operating the webseite CrypTool-Online. This portal presents the opportunity for people interested in cryptology to try out a variety of ciphers and encryption methods in their browser without downloading or installing any kind of software. This website seeks to provide a simple introduction to cryptology for first-time users and young people. The offline version of CrypTool is still available for download for advanced tasks and problems. A Smartphone version is currently under development.

The current release version, CrypTool 1.4.x, is a Windows application written in C++. There are also two successor projects in the works (currently still in beta), both using state-of-the-art standards of software development:

• CrypTool 2.0 is developed in C# with Visual Studio 2010 (Express Edition) and WPF. In July 2008, the first beta version was been released. It has since been continuously updated. CrypTool 2.0 provides a fully developed architecture and rich cryptographic functionality combined with a pioneering GUI, featuring a visual presentation of cryptographic protocols with the ability to drag and drop. Also unique is the integration of a framework for the distribution of tasks of peer-to-peer networks.
• JCrypTool is developed in Java and based on Eclipse RCP. The beta versions are updated continously. JCrypTool is platform-independent (available for Windows, Linux, and Mac) and includes the cryptographic libraries FlexiProvider (a powerful toolkit developed by the TU Darmstadt) and BouncyCastle (a library with a comprehensive API of cryptographic functions) for the Java Cryptography Architecture JCA.

Volunteers, especially programmers and students planning to write their theses, are always welcome to join in the further development of the CrypTool project.