Blog Posts


Overview of articles written by the CrypTool team.

CrypTool 2 Release 2023.2 published

Sunday, December 24, 2023

In December 2023, we released "CrypTool 2 - 2023.2", the second release version this year. The last previous version of CrypTool 2 was released in June 2023. Since June of this year, we have enriched CrypTool 2 with new components, improved existing templates and fixed various bugs. In the area of modern cryptography, we have integrated the Simplified AES cipher. As

Schülerkrypto 2023 in Kelkheim

Friday, December 8, 2023

After four years, the student crypto event sponsored by Deutsche Bank took place again on December 8, 2023 at the Eichendorff School in Kelkheim. This time, the topic was historical and modern cryptography as well as blockchains and quantum cryptography. You can also find pictures of the event on Deutsche Bank's LinkedIn page.

New Version of CrypTool 1 — CT 1.4.42 released

Tuesday, December 21, 2021

CrypTool 1.4.42 was published on December 21, 2021. Compared to CrypTool 1.4.41, this version contains a range of small bug fixes and improvements for CrypTool 1 (CT1). The open-source project CrypTool (CT) creates the most widespread e-learning programs for cryptography and cryptanalysis. The CT programs are used at many schools and universities worldwide, but also in companies and administrations to make understanding

JCrypTool version 1.0 released

Monday, November 30, 2020

Version 1.0 of JCrypTool was released today, November 30th, 2020. It is intended for beginners and experts in cryptography alike. JCrypTool is available in English and German. Already bundled are over 100 plugins that cover classical and modern cryptography. View a full list of included cryptography features.     Visit the JCrypTool download page The first milestone of JCrypTool was published already in 2007

Testing RSA moduli for shared prime factors

Thursday, May 24, 2012 (Update: Friday, August 21, 2020)

The RSA algorithm for public-key cryptography is based on the presumed difficulty of factoring large bi-prime integers, the factoring problem. However, as pointed out in Lenstra et al \[^1] it is possible, given a set of moduli, to factor some of them by finding shared primes. This way the factoring problem is bypassed using a simple greatest common divisor (gcd)

JCrypTool updates to Eclipse 2019-06

Monday, July 1, 2019

JCrypTool weekly builds are based on the latest Eclipse version 2019-06 since July 2019. Since the latest weekly builds since July 2019, JCrypTool is based on the latest Eclipse version 2019-06 and benefits from all its improvements. The next stable version of JCrypTool will be based on this Eclipse version as well. All JCrypTool downloads are available on our releases page.

Article about solving the Double-Transposition Challenge in Cryptologia

Saturday, June 28, 2014

A level X challenge in MysteryTwister 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. The according attack against the double-column transposition cipher was just described in the journal Cryptologia and is now implemented in CrypTool 2, based on the method presented in the article