This page demonstrates a variety of tools to use with the poly-alphabetic substitution cipher systems.
To crack a poly-alphabetice cipher you need to guess the repeat length of the codeword used.
If it isn't based on a keyword then you need a "crib." A crib is a word or phrase that is very likely to be in the message. Usually this will be at the start or end of the message. You can use cribs to guess the keyword(s) used to generate the cipher stream.
alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
To use a Latin or other alphabet insert it into the box below.