VigenereCrack - Cracking Vignere Ciphers the easy way
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14 May 2012
VigenereCrack is a little tool that can be used to decipher texts encrypted with the Vignere Algorithm (http://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher) .

Usage
=====
VigenereCrack has three modes of operation. It can be used to generate a table of letter distributions
for a specific cipher text and key length. Decrypt a cipher text with an specified password, and generate
a pdf containing cipher text decrypted with variations of passwords generated out of the most likely password.

!!!IMPORTANT!!!
By default the script assumes Spanish language as the natural language.
In order to crack English texts, three variables need to be adapted in main()

Letter distribution table:
''''''''''''''''''''''''''
To generate a letter distribution table out of the cipher Text A1, and with a assumed key length of 16

python3 VigenereCrack.py ../../CriptoCompeticion/TextosConcurs/A1.txt 16

Create letter distribution table only!
Finding most likely passwords with 16 characters ...


Distance of the letter distribution frequency to Spanish. (lower values are better , lowest are marked with *)

Column  00      01      02      03      04      05      06      07      08      09      10      11      12      13      14      15    
[A]: [3.667] [4.120] [3.755] *3.204* [3.396] *3.360* [3.622] [3.799] [3.892] [3.704] [3.522] [3.662] [3.463] [4.012] [3.699] [3.913] [A]: 
[B]: [3.798] [3.999] [4.065] [3.928] [4.067] [3.867] [3.835] [4.266] [4.155] [4.206] [4.169] [4.233] [4.057] [3.932] [3.477] [3.802] [B]: 
[C]: *3.149* *3.012* *3.169* [3.379] *3.177* *3.058* *3.089* *3.413* *3.073* *3.232* *2.903* *3.273* *3.106* *3.024* [3.432] *3.320* [C]: 
[D]: [4.469] [4.274] [4.641] [4.277] [4.113] [4.333] [4.335] [3.782] [4.302] *3.465* [3.948] [3.894] [4.378] [4.197] [3.817] [3.997] [D]: 
[E]: [4.211] [3.519] [3.601] [3.517] *3.279* [3.763] [3.870] [3.985] [3.825] [3.604] [3.873] [3.890] [3.897] [3.816] [3.988] [3.659] [E]: 
[F]: [4.037] [4.220] [4.323] [4.281] [4.030] [4.462] [4.440] [3.603] [4.029] [3.732] [4.608] [4.009] [4.074] [3.823] [3.878] [3.974] [F]: 
[G]: [3.387] *3.036* [3.657] *3.271* [3.560] [3.712] [3.324] [3.544] *2.888* [3.605] *3.097* *3.374* [3.789] [3.671] [4.038] [4.239] [G]: 
[H]: [4.159] [4.308] [4.259] [4.407] [4.381] [3.910] [4.550] [4.286] [4.199] [4.236] [4.204] [4.193] [3.763] [4.138] [3.874] [3.993] [H]: 
[I]: [4.076] [3.906] [3.534] [3.922] [3.972] [4.033] [3.635] [3.593] [3.923] [4.032] [4.069] [4.124] [4.036] [3.946] [4.176] [4.193] [I]: 
[J]: [3.425] [4.100] [3.569] [3.823] [3.775] [3.949] [3.570] [3.838] [3.826] [3.802] [4.269] [4.045] *3.318* [3.670] [3.379] [3.430] [J]: 
[K]: *3.227* [3.703] [3.756] [3.821] [4.004] [3.926] [3.687] [3.838] [3.355] [4.054] [3.111] [3.628] [3.918] [4.004] [4.162] [3.801] [K]: 
[L]: [3.954] [3.881] [4.253] [3.961] [3.955] [3.691] [4.071] [3.964] [4.243] [3.825] [3.636] [3.673] [3.608] [3.652] [3.941] [3.729] [L]: 
[M]: [4.029] [3.804] *3.410* [3.478] [3.689] [3.520] [3.512] [3.601] [3.723] [3.983] [3.936] [3.831] [4.048] [3.851] [4.197] [3.609] [M]: 
[N]: [3.587] [3.911] [3.666] [3.420] [3.500] [3.778] [3.603] [4.061] [3.826] [3.538] [4.064] [3.850] [3.676] *3.251* *3.334* [3.363] [N]: 
[Ñ]: [3.998] [3.956] [3.977] [4.192] [4.247] [3.732] [3.612] [4.369] [3.848] [4.286] [3.723] [3.428] [4.572] [3.921] [3.643] [3.909] [Ñ]: 
[O]: [4.451] [3.658] [3.953] [4.097] [3.653] [3.696] [4.260] [3.979] [4.728] [3.685] [3.624] [3.649] [3.531] [4.361] [3.758] [4.131] [O]: 
[P]: [3.801] [3.857] [3.955] [3.951] [3.976] [3.516] [4.110] [3.432] [3.759] [4.044] [4.235] [4.193] [4.077] [4.223] [4.275] [4.299] [P]: 
[Q]: [3.551] [3.661] [3.814] [3.533] [3.716] [4.027] [3.942] [3.946] [3.550] [3.656] [3.796] [4.026] [3.626] [3.739] *3.336* [3.795] [Q]: 
[R]: [4.233] [3.782] [3.665] [3.660] [3.826] [4.089] [4.095] [3.896] [3.688] [3.711] [3.867] [4.147] [3.902] [4.095] [3.555] [3.849] [R]: 
[S]: [3.762] [4.089] [4.225] [4.444] [3.938] [4.184] [4.173] [3.520] [4.056] [3.542] [3.571] [4.025] [3.592] [3.926] [3.846] [4.029] [S]: 
[T]: [3.442] [3.633] [3.509] [3.523] [3.374] [3.449] *3.240* *3.299* [3.689] [3.476] [3.914] [3.665] [3.888] [3.334] [4.125] *3.304* [T]: 
[U]: [3.525] [3.602] [4.120] [3.385] [3.787] [4.137] [3.688] [3.917] [3.417] [3.757] [3.860] [3.719] [3.708] [3.476] [3.925] [4.084] [U]: 
[V]: [4.239] [3.969] [4.196] [3.960] [4.195] [3.991] [3.692] [4.039] [3.688] [4.267] [3.982] [3.808] [4.080] [3.870] [4.186] [3.596] [V]: 
[W]: [4.121] [4.101] [3.765] [3.894] [3.785] [3.736] [4.117] [3.882] [3.760] [3.956] [3.733] [3.452] [3.733] [3.816] [3.926] [3.956] [W]: 
[X]: [3.803] [3.811] [3.476] [4.128] [4.142] [4.070] [3.781] [3.769] [3.806] [4.186] [4.330] [3.781] [3.927] [3.848] [4.135] [3.705] [X]: 
[Y]: [3.505] [3.572] [3.636] [4.072] [3.813] [3.665] [3.798] [3.849] [3.857] [3.763] [3.636] [4.095] [3.784] [3.694] [3.649] [3.900] [Y]: 
[Z]: [4.145] [4.271] [3.805] [4.226] [4.407] [4.101] [4.105] [4.285] [4.650] [4.407] [4.074] [4.088] [4.203] [4.460] [4.005] [4.178] [Z]: 
Column  00      01      02      03      04      05      06      07      08      09      10      11      12      13      14      15    

Most likely password is: CCCACCCTGCCCCCNT xTotal 50.220 , xClearText 0.044

The table shows the distance of a letter distribution for each column of the cipher text to the letter distribution used for analysing.
The value is calculated by x = sum[ sqrt( (n * f)**2 ) * 100 ] , over every letter of the alphabet.
n ... the letter distribution found in the text, f ... letter distribution in the natural language

Meaning that lower values represent distributions that follow more closely the natural language distribution. ( 0 being an identical distribution )

The most likely password is than generated by choosing the letter with the lowest x in for every column.


Decrypt Text
''''''''''''
To decrypt the text A1 with the password JSNGJCCTWAGQCTCXMDMKA and to store the result into clearText.txt

python3 VigenereCrack.py ../../CriptoCompeticion/TextosConcurs/A1.txt JSNGJCCTWAGQCTCXMDMKA clearText.txt

Decrypting file ../../CriptoCompeticion/TextosConcurs/A1.txt with password JSNGJCCTWAGQCTCXMDMKA, writing solution to clearText.txt

Finding the right password
''''''''''''''''''''''''''
If the most likely keys dont make up the password, used, its possible to let the script generate variations of close by passwords
and encrypt parts of the cipher text with those passwords. The result will be fused together in an single pdf file and can than
be used to guess the right password.

To do this for the cipher text A1, a password length of 21 and to store the solution in output.pdf call
 
python3 VigenereCrack.py ../../CriptoCompeticion/TextosConcurs/A1.txt 21 output.pdf

Note: this will generate a sub folder called out containing a text file for every password and deciphered text

Bugs
####
Well, time will tell ...

Notes
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If you make any real of this application or want a neat feature, let me know!

Author: Pasieka Manuel , [email protected]