The Cyber Security Challenge Germany (CSCG) is the German hacking
competition for pupils and students. There are 12 online challenges
starting on May 2nd, 2016. The juveniles have to solve different
IT-Security tasks till August.
"On the one hand, CrypTool has very efficient implementations including cryptanalysis and all relevant standards. So the tool is technically very useful. On the other hand, the visualization and presentation of the cryptographic techniques in CrypTool is excellent and there is no system that I know of that combines those two qualities in such an outstanding way."
Prof. Dr. Johannes Buchmann, TU Darmstadt
RSA sanity check
Testing RSA moduli for shared prime factors. Full article (2012-05-24)