Did you know?

That CrypTool was originally designed as an internal business application for information security training. CrypTool has since developed into an important open-source project in the field of cryptology. Over 50 volunteer developers worldwide contribute to the program.

What is CrypTool 1?

CrypTool 1 (CT1) is an open-source Windows program for cryptography and cryptanalysis. It’s the most wide-spreaded e-learning software of its kind.

What is CrypTool 2?

CrypTool 2 (CT2) is an open-source program offering an innovative visual programming GUI to experiment with cryptographic procedures and to animate their cascades.

What is JCrypTool?

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

What is CrypTool-Online?

CrypTool-Online (CTO) runs in a browser and provides a variety of encryption and cryptanalysis methods including illustrated examples and tools like password generator and password meter.

What is MysteryTwister C3?

MysteryTwister C3 (MTC3) is an international Crypto Cipher Contest offering a broad variety of challenges, a moderated forum, and an ongoing hall-of-fame.

New Chapter 12: Lightweight Introduction to Lattices, June 2020

This 90-page chapter covers the basic theory behind lattices in a lightweight fashion. The theory is accompanied with lots of practical examples, SageMath code, and cryptographic challenges. The input data of the challenges is bundled in text files in chal_i_helper.zip.


Current Book version: 12th edition, May 2018

In this free, 500+ pages book delivered with the CrypTool applications you will find predominantly mathematically oriented information on learning, using and experimenting cryptographic procedures. The 12th edition is a major update of the book.

The main chapters have been written by various authors and are independent from each another.

1. Official presentation of the CrypTool project

Last Update: October 2016
On around 50 slides, this CrypTool presentation gives an overview of the whole CrypTool project including its 5 subprojects.

2. Official presentation of the CrypTool 1 program

Last Update: September 2017
This presentation, with over 100 slides, gives an exhaustive overview about the features of CrypTool 1.4, and a short overview of the CrypTool project.

3. "Innovative" CrypTool presentation

This colorful innovative presentation, held in Spain, November 2008 by Gonzalo Álvarez Marañón, describes the past, present and future of CrypTool in a visual appealing way.

4. The RSA cipher

Last Update: November 2010
This presentation shows the basics of the RSA cipher in an attractive interactive way.
We offer it in three variants:
a) Powerpoint 2007 (for download; dynamical, animated)
b) PDF (for download; static, no interaction)
c) Flash (can be started within the browser, requires JavaScript; time-controlled replay)
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) operation.
An example implementation can be found here.

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