Question

MUST WRITE IN C++ Objective: Learn how to design classes using abstract classes and inheritance Assignment:

MUST WRITE IN C++

Objective: Learn how to design classes using abstract classes and inheritance Assignment: In cryptography, encryption is the process of encoding a message or information in such a way that only authorized parties can access it. In this lab you will write a program to decode a message that has been encrypted using two different encryption algorithms.

Detailed specifications: Define an abstract class that will be the base class for other two classes. It should have: A private member variable of the string type to hold the encrypted message. A constructor that receives the file name as a parameter and reads the text into the object. A pure virtual function decode that will be implemented in the derived classes. A function that prints the message on the screen.

Define two derived classes: CypherA and CypherB. Each one should implement its own version of decode according to the following algorithms:

CypherA should use the following key to decode the message: input character: abcdefghijklmnopqrstuvwxyz decoded character: iztohndbeqrkglmacsvwfuypjx Each 'a' in the input text should be replaced with an 'i', each 'b' with a 'z' and so forth.

CypherB should implement the "rotational cypher" algorithm. In this encryption method, a key is added to each letter of the original text. In order to decode you need to subtract 4. For example:

Cleartext: A P P L E Key: 4 4 4 4 4 Ciphertext: E T T P I

Main Program here
#include
#include
#include

#include "CypherA.h"
#include "CypherB.h"

using namespace std;

int main(int argc, const char * argv[]) {

string filename;

cout << "Enter file name to be decoded with algorithm A: ";
cin >> filename;

class CypherA messageA (filename);

messageA.decode();
cout << "Decoded message: \n";
messageA.print();
cout << endl << endl;

cout << "Enter file name to be decoded with algorithm B: ";
cin >> filename;

class CypherB messageB (filename);
messageB.decode();
cout << "Decoded message: \n";
messageB.print();
cout << endl;

return 0;
}

Answer 1

// PLEASE LIKE THE SOLUTION

// FEEL FREE TO DISCUSS IN COMMENT SECTION

#include "bits/stdc++.h"
using namespace std;

class BaseClass{
   string cipher;
   public:
   // constructor
   BaseClass(string filename){
       // open file
       ifstream f(filename);

       // now read and store in cipher
       f>>cipher;
       f.close();
   }

   string getCipher(){
       return cipher;
   }

   // virtual function
   virtual void decode() = 0;
};

// CypherA
class CypherA: public BaseClass{
   public:
   string message;
   // constructor
   CypherA(string filename):BaseClass(filename){
       message ="";
   }

   void decode(){
       string key = "iztohndbeqrkglmacsvwfuypjx";

       // now decode by substracting 4
       message ="";
       string c = getCipher();
       for(int i=0;i<c.length();i++){
           message += key[(c[i]-'a')];
       }
   }

   void print(){
       cout<<message;
   }
};

// CypherB
class CypherB: public BaseClass{
   public:
   string message;
   // constructor
   CypherB(string filename):BaseClass(filename){
       message = "";
   }

   void decode(){
       // now decode by substracting 4
       message ="";
       string c = getCipher();
       for(int i=0;i<c.length();i++){
           message += (c[i]-4);
       }
   }

   void print(){
       cout<<message;
   }
};

int main(int argc, const char * argv[]){
   string filename;
   cout << "Enter file name to be decoded with algorithm A: ";
   cin >> filename;

   CypherA messageA (filename);

   messageA.decode();
   cout << "Decoded message: \n";
   messageA.print();
   cout << endl << endl;

   cout << "Enter file name to be decoded with algorithm B: ";
   cin >> filename;

   CypherB messageB (filename);
   messageB.decode();
   cout << "Decoded message: \n";
   messageB.print();
   cout << endl;

   return 0;
}

// SAMPLE OUTPUT