--- /dev/null
+{
+ "cells": [
+ {
+ "cell_type": "code",
+ "execution_count": 1,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+ "source": [
+ "import string\n",
+ "import itertools"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 2,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+ "source": [
+ "def sanitised(text):\n",
+ " return ''.join(letter.lower() for letter in text if letter in string.ascii_letters)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 3,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'thequickbrownfoxjumpedoverthelzydoga'"
+ ]
+ },
+ "execution_count": 3,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "sanitised('The quick brown fox! jumped OVER the l\\a!z%y* dog....a')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 4,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "def encipher_letter(previous, key, current):\n",
+ " new = (ord(previous) + ord(key) + ord(current) - 3 * ord('a')) % 26\n",
+ " return chr(new + ord('a'))"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 17,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+ "source": [
+ "def decipher_letter(previous, key, current):\n",
+ " new = (ord(current) - ord(key) - ord(previous) + ord('a')) % 26\n",
+ " return chr(new + ord('a'))"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 6,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'a'"
+ ]
+ },
+ "execution_count": 6,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "encipher_letter('a', 'a', 'a')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 8,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'abcdefghijklmnopqrstuvwxyz'"
+ ]
+ },
+ "execution_count": 8,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "''.join(encipher_letter('a', 'a', l) for l in string.ascii_lowercase)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 9,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'cdefghijklmnopqrstuvwxyzab'"
+ ]
+ },
+ "execution_count": 9,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "''.join(encipher_letter('b', 'b', l) for l in string.ascii_lowercase)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 18,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'abcdefghijklmnopqrstuvwxyz'"
+ ]
+ },
+ "execution_count": 18,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "''.join(decipher_letter('a', 'a', l) for l in string.ascii_lowercase)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 21,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'yzabcdefghijklmnopqrstuvwx'"
+ ]
+ },
+ "execution_count": 21,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "''.join(decipher_letter('b', 'b', l) for l in string.ascii_lowercase)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 20,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'b'"
+ ]
+ },
+ "execution_count": 20,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "decipher_letter('a', 'a', 'b')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 23,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ 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+ ]
+ },
+ "execution_count": 23,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "''.join(encipher_letter(k, p, l) \n",
+ " for l in string.ascii_lowercase \n",
+ " for k in string.ascii_lowercase \n",
+ " for p in string.ascii_lowercase)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 24,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "[('a', 'a', 'a', 'a'),\n",
+ " ('a', 'b', 'a', 'b'),\n",
+ " ('a', 'c', 'a', 'c'),\n",
+ " ('a', 'd', 'a', 'd'),\n",
+ " ('a', 'e', 'a', 'e'),\n",
+ " ('a', 'f', 'a', 'f'),\n",
+ " ('a', 'g', 'a', 'g'),\n",
+ " ('a', 'h', 'a', 'h'),\n",
+ " ('a', 'i', 'a', 'i'),\n",
+ " ('a', 'j', 'a', 'j')]"
+ ]
+ },
+ "execution_count": 24,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "encrypted = [(k, p, l, encipher_letter(k, p, l)) \n",
+ " for l in string.ascii_lowercase \n",
+ " for k in string.ascii_lowercase\n",
+ " for p in string.ascii_lowercase]\n",
+ "encrypted[:10]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 25,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "True"
+ ]
+ },
+ "execution_count": 25,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "all(l == decipher_letter(k, p, e) for k, l, p, e in encrypted)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 39,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+ "source": [
+ "def encipher_message(plaintext, keystring='a'):\n",
+ " key = itertools.cycle(keystring)\n",
+ " ciphertext = ''\n",
+ " previous = keystring[0]\n",
+ " for letter, keychar in zip(plaintext, key):\n",
+ " cipherletter = encipher_letter(previous, keychar, letter)\n",
+ " ciphertext += cipherletter\n",
+ " previous = cipherletter\n",
+ " # previous = letter\n",
+ " return ciphertext"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 40,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'hlnbk'"
+ ]
+ },
+ "execution_count": 40,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "encipher_message('hello', 'aardvark')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 41,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'nhijn'"
+ ]
+ },
+ "execution_count": 41,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "encipher_message('hello', 'q')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 42,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+ "source": [
+ "def decipher_message(ciphertext, keystring='a'):\n",
+ " key = itertools.cycle(keystring)\n",
+ " plaintext = ''\n",
+ " previous = keystring[0]\n",
+ " for letter, keychar in zip(ciphertext, key):\n",
+ " plainletter = decipher_letter(previous, keychar, letter)\n",
+ " plaintext += plainletter\n",
+ " previous = letter\n",
+ " # previous = plainletter\n",
+ " return plaintext"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 43,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'hello'"
+ ]
+ },
+ "execution_count": 43,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "decipher_message('hlnbk', 'aardvark')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 44,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'hello'"
+ ]
+ },
+ "execution_count": 44,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "decipher_message('nhijn', 'q')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 45,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'hecoj'"
+ ]
+ },
+ "execution_count": 45,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "decipher_message('hlnbk')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 46,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'hlwhvjxlznbpdrfthvjxlznbpd'"
+ ]
+ },
+ "execution_count": 46,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "encipher_message('helloooooooooooooooooooooo')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 47,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'helloooooooooooooooooooooo'"
+ ]
+ },
+ "execution_count": 47,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "decipher_message('hlwhvjxlznbpdrfthvjxlznbpd')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 48,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "'fdkknnnnnnnnnnnnnnnnnnnnnn'"
+ ]
+ },
+ "execution_count": 48,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "decipher_message('hlwhvjxlznbpdrfthvjxlznbpd', 'b')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+ "source": []
+ }
+ ],
+ "metadata": {
+ "kernelspec": {
+ "display_name": "Python 3",
+ "language": "python",
+ "name": "python3"
+ },
+ "language_info": {
+ "codemirror_mode": {
+ "name": "ipython",
+ "version": 3
+ },
+ "file_extension": ".py",
+ "mimetype": "text/x-python",
+ "name": "python",
+ "nbconvert_exporter": "python",
+ "pygments_lexer": "ipython3",
+ "version": "3.4.2"
+ }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
projects / computing-unplugged-book.git / blobdiff