README

Vigenery. A program to encrypt/decrypt and break the vigenere cipher.

Author: Brendan Fahy <brendan@f4hy.com>

To build this project you will need GHC (or some other haskell compiler)
Build with:
      ghc --make vigenery

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Usage : vigenery [-mode] [-i input] [-k key]
Encryption
 vigenery -e -i inputfile.txt -k key
 vigenery -e -i inputfile.txt -k key -o output.txt
Decryption
 vigenery -d -i inputfile.txt -k key
 vigenery -d -i inputfile.txt -k key -o output.txt
cryptAnalysis
 vigenery -a -i inputfile.txt


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The vigenere cipher was once known as the unbreakable cipher and was used extensivly during the american civil war!

Now it is very easy to break. To break the cipher this program uses the Kasiki test, and statistical information from finding the Index of Coincidence. 


The program works pretty well, but is not very robust and does not handle bad user input well. That is coming in the next version