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