About CrypTool-Online (CTO)
Encrypt directly within your browser
CrypTool-Online provides an exciting insight into the world of cryptology. A variety of ciphers, coding methods, and analysis tools are introduced together with illustrated examples. Our emphasis is on making explanations easy to understand in order to further the general interest in cryptography and cryptanalysis. Therefore, you can experiment with the introduced methods in an interactive way directly on the website.
So you can learn the fundamentals of historically relevant ciphers in a little while, and also use the tools under Ciphers to encrypt messages yourself. You can also decrypt and analyze already encrypted messages and discover weaknesses of different ciphers. Under Highlights, you can for instance check the modern cipher AES or let the site generate good passwords for you.
CrypTool-Online is the online version of the e-learning program CrypTool. The so-called download (or offline) versions of CrypTool are also free and suitable for working with longer texts and conducting high performance analyses on encrypted messages.