No7_Shift_Operator.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import random"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Create a random message of \"n\" bits.\n",
    "def create_m(n):\n",
    "    message = []\n",
    "    for i in range(n):\n",
    "        bit = bool(random.getrandbits(1))\n",
    "        if bit == True:\n",
    "            message.append(1)\n",
    "        else:\n",
    "            message.append(0)\n",
    "    \n",
    "    return message #returns a list of bits\n",
    "\n",
    "# Left rotation of a message by n.\n",
    "def rotate(message, n):\n",
    "    return message[n:] + message [:n] #returns a list of bits\n",
    "\n",
    "# XOR function between a message and a key.\n",
    "def xor(message, key):\n",
    "    c = [0 for i in range(len(message))]\n",
    "    for i in range(len(message)):\n",
    "        temp = 0\n",
    "        if (message[i] != key[i]):\n",
    "            c[i] = 1\n",
    "    \n",
    "    return c #returns a list of bits"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Message Encryption\n",
    "m0 = create_m(16) # original message\n",
    "m6 = rotate(m0, 6)\n",
    "m10 = rotate(m0, 10)\n",
    "\n",
    "c0 = xor(m0, xor(m6,m10)) # c = m (+) (m<<6) (+) (m<<10)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Original Message: \n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1]"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Encrypted Message: \n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1]"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "print(\"Original Message: \")\n",
    "display(m0)\n",
    "\n",
    "print(\"Encrypted Message: \")\n",
    "display(c0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Message Decryption\n",
    "c2 = rotate(c0, 2)\n",
    "c4 = rotate(c0, 4)\n",
    "c12 = rotate(c0, 12)\n",
    "c14 = rotate(c0, 14)\n",
    "decr = xor(c0, xor(c2, xor(c4, xor(c12,c14)))) # d = c (+) (c<<2) (+) (c<<4) (+) (c<<12) (+) (c<<14)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Decrypted Message: \n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1]"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Original Message: \n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1]"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "print(\"Decrypted Message: \")\n",
    "display(decr)\n",
    "\n",
    "print(\"Original Message: \")\n",
    "display(m0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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