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CrypTool

Software for illustrating cryptographic and cryptanalytic concepts

Wikipedia contributorsAdapted for Fathomly · View authors
1 min read
Source updated May 22, 2026
Image credit is listed at the end of this article.

CrypTool is an open-source project that is a free e-learning software for illustrating cryptographic and cryptanalytic concepts.

01History

The development of CrypTool started in 1998. Originally developed by German companies and universities, it is an open-source project since 2001.

Currently 4 versions of CrypTool are maintained and developed: CrypTool 1 (CT1), CrypTool 2 (CT2), JCrypTool (JCT), and CrypTool-Online (CTO). All are available in English and German.

The goal of the CrypTool project is to make users aware of how cryptography can help against network security threats and to explain the underlying concepts of cryptology.

The development of CT1 started in 1998. It is written in C++ and designed for the Microsoft Windows operating system.

In 2007, development began on two additional projects, both based on a pure-plugin architecture, to serve as successors to the original CT1 program:

  • CrypTool 2 (built with C#/.NET/WPF) (abbreviated CT2)
uses the concept of visual programming to clarify cryptographic processes. Currently, CT2 contains more than 150 crypto functions.
  • JCrypTool 1.0 (built with Java/Eclipse/RCP/SWT) (abbreviated JCT)
runs on Windows, macOS, and Linux, and offers both a document-centric and a function-centric perspective. Currently, JCT contains more than 100 crypto functions. One of its focal points are modern digital signatures (like Merkle trees and SPHINCS).

The browser software CrypTool-Online (CTO) has been in development since 2010 and is now the one most widely used.

Since 2023, the project has been managed by the CODE research institute at the University of the Bundeswehr Munich.

CrypTool is used in schools, universities, companies and agencies for education and awareness training.

Watch videos about CrypToolExplainers and documentaries on YouTube (opens in a new tab)

Sources and credits

This article is adapted from the Wikipedia article “CrypTool”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

Images, from Wikimedia Commons:

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