Question

#include

#include

#include

#include

#include

#include

#include

using namespace std;

const int MAX = 26;

string addRandomString(int n)

{

  

char alphabet[MAX] = { 'a', 'b', 'c', 'd', 'e', 'f', 'g',

  

'h', 'i', 'j', 'k', 'l', 'm', 'n',

  

'o', 'p', 'q', 'r', 's', 't', 'u',

  

'v', 'w', 'x', 'y', 'z' };

  

string res = "";

  

for (int i = 0; i < n; i++)

  

res = res + alphabet[rand() % MAX];

  

return res;

  

}

string getOriginalText (string hashedText) {

  

string originalText = "";

  

for (int i=0; i//iterate over each letter in the Hashed

  

{

  

if(i%4 == 0) //if the iteration variable is multiple of 4, means every 4th element; then add the char at that position

  

originalText = originalText + hashedText.at(i);

  

}

  

return originalText;

  

}

int main()

{

cout << "--------------------------------------" << endl;

cout << " Encrypted Text File " << endl;

cout << "--------------------------------------" << endl;

cout << "" << endl << endl;

cout << "(Check Encryption file and Decryption file for result)" << endl;

  

   // srand(time(NULL));

srand((unsigned)time(NULL));

  

string hashedText = "";

  

char ch;

  

fstream fin("/Users/Andipc/Desktop/Data file.txt", fstream::in); // Navigate to Data file.txt

  

while (fin >> noskipws >> ch) {

  

hashedText = hashedText + ch + addRandomString(3) ;

  

}

{

ofstream file;

file.open ("/Users/Andipc/Desktop/Encryption file.txt"); // Navigate to Encryption file.txt

file << hashedText << endl;

file.close();

  

ofstream filez;

filez.open ("/Users/Andipc/Desktop/Decryption file.txt"); // Navigate to Decryption file.txt

filez << getOriginalText(hashedText) << endl;

filez.close();

  

}

  

cout << "" << endl << endl << endl;

return 0;

  

}

**I want you to explain any line of codes in the program.**

make it clear so I could understand.

  

  

Answer 1

Note: Please find the explanation below.

If you need further help please comment.

Please give a thumbs up. Thanks.

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Mainly This program is encrypting the data and decrypting it.

Encryption Scheme:

First it reads a file char by char. Now when it character by character it adds three random chars to it as shown below:

It is reading a and add 3 random chars oxx.

Similarly it is reading s and add 3 random chars con and merge with previous text.

Similarly it is reading d and add 3 random chars blk and merge with previous text and so on.

So by this encryption is done and final hashed value is stored in new file “Encryption file.txt”.

Decryption Scheme:

As in encryption we are adding 3 extra digits so here in decryption we are reading every 4^th digit and merging with originalText. Finally storing it new file “Decryption file.txt”

Now code explaination:

#include<string>

#include<iostream>

#include<ctime>

#include<fstream>

using namespace std;

const int MAX = 26;

//Method to get random strings of size n

string addRandomString(int n)

{

       //creating array of 26 alphabets

       char alphabet[MAX] = { 'a', 'b', 'c', 'd', 'e', 'f', 'g',

              'h', 'i', 'j', 'k', 'l', 'm', 'n',

              'o', 'p', 'q', 'r', 's', 't', 'u',

              'v', 'w', 'x', 'y', 'z' };

       //Creating temporary variable res

       string res = "";

       //Creating random string of length n

       for (int i = 0; i < n; i++)

              res = res + alphabet[rand() % MAX]; //MAX is 26 so getting random number between 0 to 25 and getting char from alphabet array and adding to res.

       //Returning string of length n

       return res;

}

//this method will take hashed text and return original text

string getOriginalText (string hashedText) {

       //taking originalText and empty string

       string originalText = "";

       for (int i=0; i<hashedText.length();i++)//iterate over each letter in the Hashedtext

       {

              //Now as in encryption we are adding 3 extra characters so in decrytion we are taking every 4th letter

              // example -->original is abcd

              //encrypted will add 3 extra characters after every character. aXXXbXXXcXXXd

              //decrypting by reading characters at position 0,4,8,12 and we get original text abcd

              if(i%4 == 0) //if the iteration variable is multiple of 4, means every 4th element; then add the char at that position

                     originalText = originalText + hashedText.at(i);

       }

       //returning original text

       return originalText;

}

int main()

{

       //Displaying output results

       cout << "--------------------------------------" << endl;

       cout << " Encrypted Text File " << endl;

       cout << "--------------------------------------" << endl;

       cout << "" << endl << endl;

       cout << "(Check Encryption file and Decryption file for result)" << endl;

       // srand(time(NULL));

       //this will generate seed to find random numbers

       srand((unsigned)time(NULL));

       //original hashedText is empty

       string hashedText = "";

       //temp character variable

       char ch;

       //opening file to read original text

       fstream fin("/Users/Andipc/Desktop/Data file.txt", fstream::in); // Navigate to Data file.txt

       //reading file character by character

       while (fin >> noskipws >> ch) {

              //adding 3 random character to the read chracter. Also merging with old hashed text

              hashedText = hashedText + ch + addRandomString(3) ;

       }

       {

              //ofstream to output encrypted text in new file

              ofstream file;

              file.open ("/Users/faraz/Desktop/Encryption file.txt"); // Navigate to Encryption file.txt

              //printing hashedText to Encryption file.txt

              file << hashedText << endl;

              //closing file so that data is saved

              file.close();

              //ofstream to output original text in new file

              ofstream filez;

              filez.open ("/Users/faraz/Desktop/Decryption file.txt"); // Navigate to Decryption file.txt

              //printing OriginalText to Decryption file.txt after converting hashed text to original text

              filez<<getOriginalText(hashedText) << endl;

              //closing file to save data

              filez.close();

       }

       //just printing extra lines

       cout << "" << endl << endl << endl;

       return 0;

}