david wong

Hey! I'm David, cofounder of zkSecurity and the author of the Real-World Cryptography book. I was previously a crypto architect at O(1) Labs (working on the Mina cryptocurrency), before that I was the security lead for Diem (formerly Libra) at Novi (Facebook), and a security consultant for the Cryptography Services of NCC Group. This is my blog about cryptography and security and other related topics that I find interesting.

Cryptool... posted March 2015

I just discovered Cryptool. I can't believed I didn't know about that earlier.

The CrypTool Portal raises awareness and interest in encryption techniques for everyone. All learning programs in the CrypTool project are open source and available for free. The CrypTool project develops the world most-widespread free e-learning programs in the area of cryptography and cryptoanalysis.

On their main page (cryptool portal) you have links to: Cryptool 1, Cryptool 2, JCryptool, Cryptool Online and Mystery Twister C3. Each project is a huge amount of information that was gathered by a group of volunteer (so yeah, for free). There are tons of tutorials and ways to play with ciphers to understand them. There is even a coppersmith and boneh-durfee explanation/implementation of the attacks I implemented these last months... This is huge. I feel like I'm just discovering the tip of the iceberg and it's all really confusing so here's a recap of what is everything, for me and for you :)

Cryptool 1


CrypTool 1 (CT1) was the first version of CrypTool. It was released in 1998 and allows to experiment with different cryptographic algorithms. CT1 runs under Windows. CT1 has two successors: CT2 and JCT.

It doesn't seem like it's useful to dig into this one since CT2 and JCT are supposed to be the updated versions. I've still installed it and it looks really old! But it's super complete and super fast so... still super useful.

Cryptool 2


CrypTool 2 (CT2) supports visual programming and execution of cascades of cryptographic procedures. CT2 also runs under Windows.

I skimmed through it seeing no resemblance to CT1. I have to spend more time with it but CT1 seemed way more educational and complete...



JCrypTool (JCT) is platform-independent and runs under Linux, Mac and Windows.

Haven't tried it yet but it looks like a multiplatform CT2

Cryptool Online

CrypTool-Online (CTO) was released in spring 2009. This tool allows to try out different algorithms in a browser / smartphone.

I'm gonna be honest here, not really nice compared to CT1 and CT2. Pretty limited.

Mystery Twister C3

You like riddles? You always loved to solve the crosswords in your newspaper? Or maybe you are just curious and want to find out about some of the ways to hide a secret (and possibily even to uncover it)? This is your place! Here at MysteryTwister C3 you can solve crypto challenges, starting from the simple Caesar cipher all the way to modern AES we have challenges for everyone.

The first riddle is just a sequence a number where you have to guess the last entry. Typical IQ test but it has been solved by 2138 people.

The 29th riddle is Hadstad broadcast attack and had only been solved by 102 people.

There are raffles every month so it might be a nice playground :) play here

Well done! You've reached the end of my post. Now you can leave a comment or read something else.



I am one of the contributors to the CrypTool project and may be able to add some information:
1) A presentation given in Norway 2013 could be helpful to get an overview of the whole project.
All three (CT1, CT2 and JCT) are still maintained. Most new development goes into CT2 and JCT.
2) Resemblance of CT2 with CT1
> I have to spend more time with it but CT1 seemed way more educational and complete...
CT2 has a complete different interface -- inspired from visual programming.
From an educational perspective it should be more modern as CT1 as its much more interactive.
3) At https://www.cryptool.org/en/ctp-documentation-en/ctp-functions-en
you can compare which functions are in the different versions. Please notice, that the list on the web is not quite current (so actually there are more than 400 functions overall).
4) JCT has a similar GUI as CT1, however it is platform independent and "Eclipse-minded".
A presentation about JCT can be found here:
- For developers: https://github.com/jcryptool/core/wiki/Getting-started-as-a-JCrypTool-Developer
- For users: https://github.com/jcryptool/doc/raw/master/pdf/jcryptool_presentation_en.pdf
Best regards, Sven (April 5th, 2013)

PS: We'd like to write "CrypTool" with a capital "T" [it's just for historical reasons as the CrypTool started in the "old days" just before year 2000 when many projects and companies had this temporary fashion switching to capitalization within a single word. Additionally, one of the developers was a fan of the the Hungarian notation] :-)


Thanks for the clarifications Sven!

leave a comment...