CryptoToolJ User Guide

Overview

CryptoToolJ is a Java-based application program that supports encryption, decryption, and cryptanalysis of text file using a variety of simple historical ciphers.

Encryption/Decryption: Encrypting operations require that the user create the appropriate cryptographic key, and decrypting operations require the user supply the correct key. The following ciphers are implemented in the default version, although additional cipher engines can be added to through tool as plugins. Clicking on their links gets additional information about the cipher method itself.

CIPHER	Description of the Key
Caesar	An integer by which each letter is shifted
Simple Substitution	A keyword or a permutation of A..Z
Transposition	A String, such as 1023, describing the reordering of a block of text
Vigenere	A keyword
Gronsfeld	A keyword
Beaufort	A keyword
Autoclave	A keyword
Playfair	A keyword
Railfence	An integer > 0 giving number of rows

Key Dialog CryptoToolJ provides a key dialog window to assist with creating and using keys.

Cryptanalysis: Once a message has been typed into CryptoToolJ's textarea, a variety of programs can be used to cryptanalyze it. The following analyzers are implemented in the default version, although additional analyzers can be added as plugins.

Analyzer	Description
Index of Coincidence	Displays the message's index of coincidence.
TextAnalyzer	Displays frequency data in an interactive histogram.
AffineAnalyzer	Attempts to break the text assuming affine encryption.
CaesarAnalyzer	Attempts to break the text assuming Caesar encryption.
SubstitutionAnalyzer	Attempts to break the text assuming simple substitution encryption.
VigenerAnalyzer	Attempts to break the text assuming Vigenere encryption.

Using CryptoToolJ to Encrypt/Decrypt Messages

When CryptoToolJ is started, its main window opens:

This window is not interactive. It just reports the status of the program and it can also be used by analyzers to report their results. CryptoToolJ has four menus, File, Edit, Window, and Analysis. To encrypt or decrypt a file or a message, use the file menu to open a Cipher Window:

Cipher windows are numbered and more than one can be open at a time, although only the front window is considered active. The window's title shows the name of the cipher engine that has been selected for that window.

This window contains a choice-box menu that lists the available cipher engines. The Caesar cipher is the default choice. When the Cipher window is initially opened, its Encrypt and Decrypt buttons are de-activated and remain so until the cryptographic key is specified. Once the cipher engine has been selected, clicking on the Key Button will open the Key Dialog:

To specify a valid cryptographic key, you must select the plaintext alphabet and ciphertext alphabet and provide the key data. In this example, the key data consists of the Caesar shift. For most other cipher engines, the key data would consist of a keyword. In either case, the key data is used to generate the cryptographic key, which is some permutation of the alphabets.

The alphabets may be specified by choosing from among the checkbox options and/or by designating other and typing in a valid alphabet descriptor. The alphabet descriptor may be composed of any combination of Unicode character ranges and Unicode block names. Here are some examples.

Descriptor	Meaning
Range.ai+Range.kz	Lowercase a to z except for j
Range.ai+Range.kz+Range.AI+Range.KZ	Lower- and uppercase a to z except for j
UnicodeBlock.GREEK	The standard Greek alphabet
UnicodeBlock.HIRAGANA+UnicodeBlock.KATAKANA	The standard Japanese alphabets

Any alphabet ranges specified in the Other field, are added to those selected by checkboxes. (NOTE: CryptoToolJ does not currently recognize all Unicode blocks by name.)

Once a valid key has be specified, the Encrypt and Decrypt buttons will become activated. When either button is clicked, its action will be applied to the text in the Input TextArea and the result will be displayed in the Output TextArea. Here's the result of a Caesar encryption.

Menus

File Menu

New Cipher opens a Cipher Window, which then controls all encryption and analysis tasks.
Open File opens a Cipher Window and then uses a File Dialog to prompt the user for a file. The file's text is read into the window. (This option is not available in the applet version.)
Close Cipher closes Cipher Window, prompting the user to save any text that has been modified.
Save saves the designated text to a file. (This option is not available in the applet version.)
Save As renames and saves the designated text to a file. (This option is not available in the applet version.)
Print prints the designated. (This option is not yet implemented.)
Quit quits the program, prompting the user to save any text that was modified.

Edit Menu

The Edit Menu consists of the standard Cut, Copy, Paste, and Select all options.

Window Menu

The Window Menu helps to manage the Main Window and any Cipher Windows that are opened. Selecting a window from the menu will bring that window to the front.

Analysis Menu

The Analysis Menu lists the names of the various Analyzers that are available. When an Analyzer is selected, it will be applied to the currently activated textarea within the current Cipher Window. If no textarea or no window is active, the command is ignored.