Question

C++ please

Programming Assignment #6 Help Me Find The Secret Message Description: This assignment will require that you read in an encrypted message from a file, decode the message, and then output the message to a file. The encryption method being used on the file is called a shift cipher (Info Here). I will provide you with a sample encrypted message, the offset, and the decrypted message for testing. For this project I will provide you main.cpp, ShiftCipher.h, and ShiftCipher.cpp. It is your task to add the code required to make them run as explained within the codes TODO comments and this specification. Changes to ShiftCipher.h are not allowed. Programming Specifications: 1. BEFORE STARTING YOU MUST UPDATE CLION TO WORK IN YOUR CURRENT DIRECTORY a. In order for CLion to use a relative path to find your files your project must be set up to use your current directory. i. First right click on your project folder within CLion 1. Then under copy select "absolute path" Complete Project Com crypt Reload Make Project Recome OXF9 MAX ce Copy Copy XC Copy Path Absolute Path Toolbox URL w Texts Find Usages She Replace in Puth OUR ii. Then select Run > edit configurations 1. Once the screen pops up paste the absolute path in the working directory box and select apply

Answer 1

// ShiftCipher.h
#ifndef SHIFTCIPHER_H
#define SHIFTCIPHER_H

#include <string>
using namespace std;

class ShiftCipher
{
public:
ShiftCipher(); // default constructor
void setOffset(int messageOffset); // set the offset
string Encode(string message); // encode the input message and return the encoded message
string Decode(string message); // decode the input message and return the decoded message

private:
int offset;
};
#endif // SHIFTCIPHER_H

//end of ShiftCipher.h

// ShiftCipher.cpp
#include "ShiftCipher.h"

// default constructor to set offset to 0
ShiftCipher::ShiftCipher()
{
offset = 0;
}

// function to set the offset to the input messageOffset
void ShiftCipher::setOffset(int messageOffset)
{
offset = messageOffset;
}

// function to encode the given message using offset as the shift and return the encoded message
string ShiftCipher::Encode(string message)
{
string encodedMessage = ""; // create an empty string to store the encoded message
// since ascii code between [32,122] are allowed, hence total number of allowed characters is 91
int range = 91; // 122-32+1

// loop to encode each character in the message and append the encoded character to encodedMessage
for(size_t i=0;i<message.length();i++)
{
// to keep ascii code between [32,122]
// first subtract the ascii code of ith character from lowest code in the range, then add offset
// then to get the code between [0,90] take modulus of range and then add back 32 to get the decoded character
encodedMessage += (char)(((((message[i])-32) + offset)%range) + 32);
}

return encodedMessage;
}

// function to decode the given message using offset as the shift and return the decoded message
string ShiftCipher::Decode(string message)
{
string decodedMessage = ""; // create an empty string to store the decoded message
// since ascii code between [32,122] are allowed, hence total number of allowed characters is 91
int range = 91;// 122-32+1

// loop to decode each character in the message append the decoded character to decodedMessage
for(size_t i=0;i<message.length();i++)
{
// to keep ascii code between [32,122]
// first subtract the ascii code of ith character from lowest code in the range, then add the value return after subtracting offset from range
// then to get the code between [0,90] take modulus of range and then add back 32 to get the encoded character
decodedMessage += (char)((((message[i] - 32) + (range-offset))%range) + 32);
}

return decodedMessage;

}

//end of ShiftCipher.cpp

// main.cpp : C++ program to implement ShiftCipher class to decrypt a message read from the file using offset which is also read from the file
#include <iostream>
#include <string>
#include <fstream>
#include "ShiftCipher.h"

using namespace std;

// function declaration
void runDecryption();
string getEncryptedFileName();
string readEncryptedFile(string name, int &messageOffset);
string getDecryptedFileName();
void outputtoFile(string name, string message);

int main()
{
runDecryption();
return 0;
}

// function to run the decryption process
// Input : None
// Output : None
void runDecryption()
{
string encrypted_name, decrypted_name;
string encrypted_message, decrypted_message;
int offset;

// create a ShiftCipher object using default constructor
ShiftCipher cipher;

// get the encrypted file name from the user
encrypted_name = getEncryptedFileName();

// set the offset for the shift cipher read from the file
encrypted_message = readEncryptedFile(encrypted_name, offset);
cipher.setOffset(offset);

// decode the message using your ShiftCipher
decrypted_message = cipher.Decode(encrypted_message);

// get the output file name from the user
decrypted_name = getDecryptedFileName();

// output the message to the file
outputtoFile(decrypted_name, decrypted_message);
}

// function to get the encrypted filename from user and return it
// Input : None
// Output : string, the name of the encrypted file
string getEncryptedFileName()
{
string filename;
// input the file name from user
cout<<"What is the name of your encrypted file? ";
cin>>filename;
return filename;
}

// function to read the encrypted file to get the offset and return the encrypted message
// Inputs:
// name - string, name of the input encrypted file
// messageOffset - int, reference to return the offset read from the file
// Output: string, message read from the file
string readEncryptedFile(string name, int &messageOffset)
{
ifstream fin(name); // open the file
string message = "";

// check if file was opened
if(fin.is_open())
{
fin>>messageOffset; // read the message offset
fin.ignore(); // ignore '\n' left by cin
// read the next line of message
getline(fin, message);

fin.close(); // close the file
}

return message;
}

// function to get the decrypted filename from user and return it
// Input: None
// Output - string, filename of the decrypted file
string getDecryptedFileName()
{
string filename;
// input the name of the decrypted file
cout<<"What is the name of your decrypted file? ";
cin>>filename;
return filename;
}

// function to output the decoded message to output file
// Inputs:
// name - string, of output decrypted file
// massage - string, decrypted message to write to the file
void outputtoFile(string name, string message)
{
// output the message on screen
cout<<"message being save to "<<name<<" is:\n";
cout<<"\t"<<message<<endl;

ofstream fout(name); // open the output file

// check if file was opened successfully
if(fout.is_open())
{
fout<<message; // output the decoded message
fout.close(); // close the file
}
}

//end of main.cpp

Output:

Input files should be in the same folder as the source code files, so that it can be accessed directly using the filenames

Input file : encryptedMessage.txt

1 2 2 rtqitcookpi"ku" cygugog

Console:

What is the name of your encrypted file? encryptedMessage.txt What is the name of your decrypted file? decryptedMessage.txt message being save to decryptedMessage.txt is: programming is awesome

Output: decryptedMessage.txt

1 programming is awesome

Input file: encryptedMessage2.txt

1 5 2 nymnsp%ymnxnx&fexjsyjshj

Console:

What is the name of your encrypted file? encryptedMessage2.txt What is the name of your decrypted file? decryptedMessage2.txt message being save to decryptedMessage2.txt is: i think this is a sentence

Output file : decryptedMessage2.txt

1 i think this is a sentence