CrypTool

CrypTool allows to study encryption and decryption algorithms in a friendly environment, and put into practice the gained knowledge about cryptography and cryptoanalysis.

The application has a basic GUI, comprised of the main menu, a toolbar, and the main work area. The toolbar has ugly crafted icons, not to mention that they seem too small. Also, the grey theme color gives the impression of a faded and outdated look.

If you're a novice user, you need to know that CrypTool contains comprehensive online help about every built-in cryptographic function and method, along with multiple languages support.

As per included algorithms, they represent both classic and modern cryptosystems. The modern methods include hybrid encryption, RSA and AES algorithms, while the classic ones are illustrated by the Enigma algorithm, the Caesar cipher, or the double-column transposition.

This tool allows users to create a text authentication code via the HMacMD5 algorithm, encrypt and decrypt messages with AES, or generate pseudo-random data with SHA1.

In conclusion, CrypTool is a free and very useful software program for learning cryptography and cryptoanalysis in an enjoyable environment.