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Cryptanalysis

All this grown on my deepest love to all kind of math-based algorythms and, especially, cryptographic ones. Or, if you are fan of the naked truth, on fear of nearest test.

The following ciphers are currently being studied:

  • Caesar - simpliest pre-historical cipher.
  • Affine - substitution cipher, studied as abstraction of most shift ciphers.
  • Viginere - polyalphabetic substitution, aesy to uderstand and hard to analyse.

Usage

Each file can be used like an executable:

# Simple test.
$ ./pycry/cipher/classic/affine.py 'EJJEKI EJ NESR'
Analysis...
Defined language is en.
ATTACK AT DAWN
Decryption parametres is a=3 and b=4.

# Encrypting english sample.
$ ./pycry/cipher/classic/affine.py -e 9x23 sample/en.opentext > sample/en.affine

# Analyzing encrypted.
$ ./pycry/cipher/classic/affine.py sample/en.affine 
Analysis...
Defined language is en.
['TO BE, OR NOT TO BE: THAT IS THE QUESTION:', 
# Looong decrypted message ... 
Decryption parametres is a=9 and b=23.

Also, each file can be used like module:

$ ipython3
In [1]: import pycry.cipher.classic.affine as a

In [2]: secret = a.Affine('EJJEKI EJ NESR')

In [3]: secret
Out[3]: EJJEK IEJNE SR

In [4]: secret.statistic
Out[4]: [('E', 4), ('J', 3), ('R', 1), ('S', 1), ('K', 1), ('I', 1), ('N', 1)]

In [5]: secret.decipher()
Out[5]: ('ATTACK AT DAWN', 3, 4)