Skip to main content
Help improve PyPI by participating in a 5-minute user interface survey!

Simple cryptanalysis library

Project Description

https://travis-ci.org/jamchamb/etao.svg?branch=master https://img.shields.io/codecov/c/github/jamchamb/etao.svg?maxAge=2592000

etao is a simple Python library that assists in the creation of cryptanalysis tools.

Installation

Install with pip:

pip install etao

Example Application

The following is a Caesar cipher solving tool that uses etao’s frequency analysis functions and built-in ciphers.

#!/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:

$ ./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%)

Release history Release notifications

This version
History Node

0.6.0

History Node

0.5.0

History Node

0.4.0

History Node

0.3.0

History Node

0.2.1

History Node

0.1.0

History Node

0.0.0

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Filename, size & hash SHA256 hash help File type Python version Upload date
etao-0.6.0.tar.gz (23.4 kB) Copy SHA256 hash SHA256 Source None Feb 15, 2017

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging CloudAMQP CloudAMQP RabbitMQ AWS AWS Cloud computing Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page