A program for Creating and Analysing Classical Ciphers. jkrypto is a Java program which can be used to create and analyse classical substitution and transposition ciphers. It is a rewrite of a much older program krypto.

You can use JKrypto to encrypt/decrypt text messages using either a mono or polyalphabetic vigenere, beauford or general substitution cipher, using an alphabetic key to specify the alphabets; or using a row or column transposition cipher given a key which is either a word or a permutation.

You can use jkrypto to en/decrypt text messages using either a mono or polyalphabetic vigenere, beauford or general substitution cipher, using an alphabetic key to specify the alphabets; or using a row or column transposition cipher given a key which is either a word or a permutation.

You can also use jkrypto to analyse ciphers of these forms by tabulating or graphing frequency distributions and computing IC's over 1 or multiple alphabets; searching for repeated strings of a specified size to implement the kasiski method; exhaustively searching all row or column permutations to match a search string to break these transpositions, and to reformat the data into a specified block size and number per line. These can be used to assist an analyst to break modest sized ciphers of these types.

To use jkrypto you can invoke it either with or without a filename argument:
java -jar jkrypto.jar file
will run jkrypto in command-line mode, analysing the named file
java -jar jkrypto.jar
will run jkrypto using the GUI interface

Requirements:
* Java

The license of this software is Freeware, you can free download and free use this file encryption software.