CrypTool 1 (CT1) is an open-source Windows program for cryptography and cryptanalysis. It’s the most wide-spreaded e-learning software of its kind.
CT 2.0 released
The release version of CrypTool 2.0 was released on 20th Aug 2014. We would be happy if many of you use it for teaching, self-study, education and awareness and give us feedback. (2014-08-25)
Article about solving the Double-Transposition Challenge in Cryptologia
A level X challenge in MysteryTwister C3 by Klaus Schmeh using the double-column transposition cipher withstood a long time against cryptanalysis efforts. Nevertheless, it was solved in November 2013 by George Lasry. (2014-06-25)
The 10th Beta of CrypTool 2 was released on 19th October 2013. You are cordially invited to test and give feedback. Final version of CT 2 is planned to be published in July 2014.
Land der Ideen - Statements
"CrypTool includes an unparalleled array of cryptologic tools, which are ideal for anyone who wants to study cryptography or cryptanalysis. CrypTool is a free application, readily available on the Internet."