Tutaj znajduje się podsumowanie najważniejszych funkji obecnej wersji CrypTool (najnowszej wersji stabilnej). Funkcje te różnią się od funkcji następców , które są obecnie w budowie.

CrypTool jest darmowy program, który umożliwia zastosowanie i analizowanie mechanizmów kryptograficznych. Posiada typowy wygląd i styl nowoczesnych aplikacji systemu Windows. CrypTool zawiera obszerną pomoc online , która może być zrozumiana bez rozległej wiedzy o tematcie kryptografii. CrypTool jest dostępny w języku angielskim, niemieckim, polskim i hiszpańskim. CrypTool zawiera prawie wszystkie funkcje state-of-the-art i pozwala dowiedzieć się jak i wykorzystać wjęcej na temat kryptologii.

• metody klasyczne: np. szyfr Caesar, szyfr ADFGVX, transpositie podwójnych kolumn(permutatia) i algorytm szyfrowania Enigmy
• metody nowoczesne: np. algorytmy RSA i AES, algorytmy szyfrowania hybrydowe i algorytmy w oparciu o siatkę i zmniejszenie krzywych eliptycznych

Podsumowanie wszystkich algorytmów szyfrowania realizowane w CrypTool są dostępne na stronie pomocy pod menu szyfrowanie / deszyfrowanie. Wiele zrzutów ekranu można znaleźć na tej stronie internetowej oraz są zawarte w prezentacji CrypTool .

Jeśli zostaje szyfrowany dokumentu wynik jest wyświetlany w nowym oknie: tytuł nowego okna zawiera zarówno nazwę oryginalnego dokumentu jak i zastosowany klucz szyfrujący. Korzystanie z dwóch specjalnych ikonek: Kliknięcie ikony Pokaż klucz pozwala przechowywać kopię klucza z danego okna w wewnętrzne przechowywanie. Jeśli następtnie zostaje szyfrowany inny dokument o tej samej metody szyfrowania, ikonka Wstaw klucz wpisuje zapamiętany klucz w danym oknie dialogowym. Jest to pomocne, zwłaszcza przy bardziej skomplikowanych kluczach.

Narzędzia do automatycznej analizy klasycznych algorytmów szyfrowania są przewidziane w celu uzyskania klucza zaszyfrowanego dokumentu lub karty pokładu (ewentualnie przy użyciu wszelkich dodatkowych informacji, takich jak nieszyfrowany dokument lub język dokumentu). Aby uzyskać dodatkowe informacje dotyczące automatycznej analizy, w CrypTool pomocne jest przejście do ekranu menu analizy i wybrania analizy algorytmu szyfrowanego.

Do pomocy ręcznej analizy dokumentów, CrypTool może wyświetlić histogram danego dokumentu, określić statystyki N-gramu i obliczyć entropie i autocorrelatie.

The encryption functions within the menu Crypt/Decrypt are implemented in a way that they can be called upon and performed efficiently. On the other hand, the functions in the menu Indiv. Procedures are implemented in a way that they can be performed step by step and interactively. In this 2nd menu the main focus is on e-learning.

• calculate hash values and show their sensitivity
• create Message Authentication Codes (MACs)
• find out how strong keys can be generated from passwords according to the PKCS#5 standard
• compress and decompress documents. This enables the study of file compression prior to the actual encryption of a given document
• generate or analyze pseudo random numbers
• demonstrate protocols for authentication und key exchange (DH)
• step through some ciphers forward and backwards (using the animation software ANIMAL)
• apply common encodings like base64 and uuencode

Which menu items can be selected depends on the type of the active document. The menus and sub-menus of CrypTool are dynamically generated, depending on the opened document's type (binary or text). All menu items are visible all the time, but only the ones which fit to current document type can be selected. The remaining menu items are disabled. An overview of all menu items (menu tree) within CrypTool can be found in appendix A of the script.

Within CrypTool the modern algorithms are implemented according to international standards. The authors of CrypTool did not implement cryptographic functionality where good free programs were available on the internet: So e.g. dictionary attacks against password files (see John-the-Ripper) are not part of CrypTool yet. Nevertheless CrypTool contains a tool to check out the quality of your passwords.

The RSA Cryptosystem

The RSA cryptosystem (see menu Indiv. Procedures \ RSA Cryptosystem \ RSA demonstration) is covered comprehensively and implemented for different codings. The RSA key can be generated from prime numbers selected by the user. Key generation, encryption and decryption can be followed step-by-step.

Factorisation of numbers is also an important application for cryptography. Simple RSA cryptosystems can be easily cracked using the factorisation algorithms presented in CrypTool. Thus, you get an idea of the minimum length of keys necessary for secure systems.

Interactive Demonstrations / Visualizations

These interactive demonstrations (visualizations) are helpful for improving the understanding of the following topics:

• creating an electronic signature (menu Digital Signatures/PKI \ Sign Message)
• processing hybrid encryption (menu Crypt/Decrypt \ Hybrid \ RSA-AES Encryption)
• how do modifications to a document change the hash value
  • sensitivity of hash algorithms (menu Indiv. Procedures \ Hash \ Hash Demonstration)
  • generation of hash value collisions (birthday paradox) (menu Analysis \ Hash \ Attack on the Hash Value of the Digital Signature)
• Diffie-Hellman key exchange (menu Indiv. Procedures \ Protocols \ Diffie-Hellman Demonstration)
• side-channel attack (menu Analysis \ Asymmetric Encryption \ Side-Channel Attack on Textbook RSA)
• authentication protocols (menu Indiv. Procedures \ Protocols \ Network Authentication)
• shared secrets using Chinese Remainder Theorem (menu Indiv. Procedures \ Chinese Remainder Theorem Applications \ Secret Sharing by CRT) and Shamir (menu Indiv. Procedures \ Secret Sharing Demonstration (Shamir))
• visualizations of some algorithms (e.g. Vigenère, AES, Enigma) (menu Indiv. Procedures \ Visualization of Algorithms)
• find out how an ancient number theoretic theorem (Chinese Remainder Theorem) can be applied (e.g. when are the planets of our solar system positioned in one straight line) (menu Indiv. Procedures \ Chinese Remainder Theorem Applications \ Astronomy and Planetary Motion)
• 3D visualization of big sets of random numbers (menu Analysis \ Analyse Randomness \ 3D Visualization)
• computer based training for number theory (menu Indiv. Procedures \ Number Theory - Interactive \ Learning Tool for Number Theory)
• point addition on elliptic curves (menu Indiv. Procedures \ Number Theory - Interactive \ Point Addition on Elliptic Curves)

Besides the interactive demonstrations the CrypTool package contains the educational game The Number Shark, which trains pupils to calculate factors of integer numbers.

Online help, documentation and tutorials

During the development of CrypTool, much care has been taken to ensure that context sensitive help is available at any point by pressing the F1 key. You can get a fast overview, if you move through the menu items: Just click F1 to see details about any menu item.

• explanation of all basic cryptographic terms
• a short list of references.
• a chronology of the development in cryptography
• examples (tutorials) for an easy kick off
• a well sorted index of cryptographic topics

• The readme file contains all important elements of the CrypTool package, new features of this version, a description of the project, and how to install and use CrypTool
• The CrypTool presentation, with about 100 slides, gives an overview of the CrypTool project and CrypTool's features
• In the script (provided as a PDF file with about 200 pages) you will find more, mathematically-oriented information about
  • cryptographic methods
  • prime numbers
  • elementary number theory with many examples
  • current results of the cryptanalytic research
  Additionally the appendix contains a list of movies and novels where cryptography plays a role.
• In the fantasy story The Dialogue of the Sisters by Dr. Carsten Elsner two sisters in a psychiatric hospital use a variant of the RSA cryptosystem
• Within the fantasy story The Chinese Labyrinth by Dr. Carsten Elsner, Marco Polo has to solve some number theoretic problems to become a chief advisor of the Great Khan

We are appreciative for the support of the following companies and projects:

• For the hash functions, symmetric and asymmetric ciphers, and key management, CrypTool 1.x uses the Secude Toolkit. That toolkit has been made available for us by the Secude IT Security GmbH. At the enclosed Secude toolkit the support for smart cards has been deactivated. However, if you hold a valid license for the Secude library, you can use your ticket file to activate smart card support in CrypTool 1.x.
• For the demonstration of ECC-AES hybrid encryption, we leverage the "cv act library" from cryptovision.
• For the demonstration of both the RSA crypto system, and the factorisation of numbers, CrypTool uses the ‘Miracl’ library for arbitrary precision arithmetic. The Miracl library is provided by Shamus Software Ltd.
• For the demonstration of hash collisions (birthday paradox), CrypTool uses the OpenSSL library libeay32.dll.
• For the attacks against RSA based on lattice basis reduction (LLL), we use the number theory library NTL from Victor Shoup.
• We also use the GMP library for primality tests.