https://github.com/jamchamb/etao

:pencil: Simple cryptanalysis library
https://github.com/jamchamb/etao

Last synced: about 2 months ago
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:pencil: Simple cryptanalysis library

• Host: GitHub
• URL: https://github.com/jamchamb/etao
• Owner: jamchamb
• License: gpl-3.0
• Created: 2016-02-09T05:50:52.000Z (almost 9 years ago)
• Default Branch: master
• Last Pushed: 2021-07-07T16:48:53.000Z (over 3 years ago)
• Last Synced: 2024-11-01T10:03:06.951Z (2 months ago)
• Language: Python
• Homepage:
• Size: 63.5 KB
• Stars: 5
• Watchers: 3
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.rst
  • License: LICENSE

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README

        
etao

====

.. image:: https://badge.fury.io/py/etao.svg

    :target: https://badge.fury.io/py/etao

etao is a simple Python library that assists in the creation

of cryptanalysis tools. It takes care of common low-level tasks

such as converting letters to numeric values or splitting a buffer

into a bit stream or series of fixed-size blocks, as well as higher-level

things like frequency analysis.

Installation

------------

Install with pip::

    pip install etao

As of version 1.0.0 this library switched from Python 2 to Python 3; for

Python 2 use version 0.6.0.

Example Application

-------------------

The following is a Caesar cipher solving tool that uses etao's frequency

analysis functions and built-in ciphers.

.. code:: python

 #!/usr/bin/env python

 # Caesar cipher solver

 import argparse

 from etao import CaesarCipher, NgramFrequencyScorer

 from etao.freq import ENGLISH_DIGRAMS

 def main():

     parser = argparse.ArgumentParser(description="Caesar cipher solver")

     parser.add_argument('ciphertext', type=str, help='text to decipher')

     args = parser.parse_args()

     scorer = NgramFrequencyScorer(freq=ENGLISH_DIGRAMS)

     # Get every Caesar shift of the ciphertext

     shifts = [CaesarCipher(n).decrypt(args.ciphertext) for n in range(26)]

     # Score each shift according to English character frequency.

     # Get tuples that pair the score with the text.

     scored_shifts = [(scorer.score(shift), shift) for shift in shifts]

     # Sort by score, descending order

     scored_shifts.sort(reverse=True)

     # Print the top 3 results

     for result in scored_shifts[0:3]:

         print('"%s" (%02d%%)' % (result[1], int(result[0] * 100)))

 if __name__ == "__main__":

     main()

Here's what it looks like in action:

.. code-block:: console

    $ ./caesar_solver.py "O GQFSOAWBU QCASG OQFCGG HVS GYM. WH VOG VODDSBSR PSTCFS, PIH HVSFS WG BCHVWBU HC QCADOFS WH HC BCK."

    "A SCREAMING COMES ACROSS THE SKY. IT HAS HAPPENED BEFORE, BUT THERE IS NOTHING TO COMPARE IT TO NOW." (75%)

    "U MWLYUGCHA WIGYM UWLIMM NBY MES. CN BUM BUJJYHYX VYZILY, VON NBYLY CM HINBCHA NI WIGJULY CN NI HIQ." (36%)

    "P HRGTPBXCV RDBTH PRGDHH IWT HZN. XI WPH WPEETCTS QTUDGT, QJI IWTGT XH CDIWXCV ID RDBEPGT XI ID CDL." (35%)