Wednesday, May 12, 2021

CrypTool 2 Release 2021.1 published

CrypTool 2General News

In May 2021, we published the release "2021.1", which is the first one this year and a major functional update. The last CT2 release was published in April 2020.

A YouTube video showing the changes in the new version can be watched here: What is New in the CrypTool 2 Release 2021.1?

In this new release of CT2, the Workspace Manager allows undo and redo of component settings. Some modern ciphers are added, e.g. ChaCha, and new steganography components are implemented. We introduced visual cryptography for the first time in CrypTool 2. Of course, many bugs, typos, etc. were fixed.

From a developer's perspective it may be interesting that the C# namespace "Cryptool" (historically named wrong) was renamed to "CrypTool". This internal namespace change can cause some problems when installing this version over an old version.

HINT: If you encounter any problems during the startup of CT2 after the update, please first try to restart it once more. If this does not fix the problem, please delete all CrypTool folders in your %APPDATA% folder and all of its sub directories. Thank you.

Thanks to the many users who sent feedback, requests, laud, and criticism. We hope that you have as much fun using CT2 as we have creating it!

Stay safe and healthy!

Sincerely yours, The CrypTool 2 Developer Team, May 2021

Changelog summary:

Here is a more detailed summary of the many updates and additions.

Core components:


  • A bug was fixed which caused problems with F11 and F12 when the Workspace Manager's settings were visible.
  • We automatically translated CT2 (and all components) to simplified Chinese. Keep in mind that the translation can be poor. So this is not considered as a language release yet. We would appreciate if native Chinese speakers help us to correct this automatic translation.

Workspace Manager (WSM):

  • Undo and redo is now possible with settings.
  • A bug was fixed which lead to a crash in the UI thread when components were moved while the Ctrl key was pressed.


  • The layout of the Startcenter was slightly changed by separating main functions and external functions and by showing these in different boxes.

Language statistics/models:

  • All our language models have been recalcultes using the Gutenberg library and Wikipedia text corpora.
  • Five new language models were introduced: Dutch, Swedish, Portuguese, Polish, and Turkish.



  • The old steganography components were removed. Instead, new text and image steganography components were added including the BPCS steganography algorithm.

Visual Cryptography:

  • New components in CT2 now allow to use visual encryption with text and images.


  • The ChaCha cipher of Bernstein (with a visualization of the cipher's internal states) has been implemented in CT2.

Blow, Twofish, and Threefish:

  • Now all three algorithms invented by Bruce Schneier are integrated in CT2.

Enigma Analyzer:

  • The Enigma analyzer was reimplemented using new state-of-the-art attacks implemented by George Lasry. To allow a fast attack, we also (re-)implemented the attack developed by Jim Gillogly.

DES Visualization:

  • A bug was fixed showing wrong bits in the visualization of the Data Encryption Standard (DES) in the DES visualization component.

VIC Cipher:

  • The Soviet cipher VIC used by agent Reino Häyhänen (Victor=VIC) was implemented in CT2.

Boolean Input:

  • The old ions were replaced by icons for color blind users.


  • A bug was fixed in the key schedule visualization.

Homophonic Substitution Analyzer:

  • A few performance optimizations have been added.

DECRYPT project:

  • A commandline version was built to be used in the DECRYPT pipeline.

... and many more small bugfixes, improvements, etc.

Posted by:

Nils Kopal