Question

In C++

Write a program that contains a function, encrypt(Cypher) that encrypts the below text and a second function, decrypt(Cypher),  that decrypts the encrypted message back to normal.  Cypher is the string which contain the plain or cypher texts.  Demonstrate that the encrypted message that you created is correctly decrypted.  For this problem you need to input “All Gaul is …” into a string Cypher.  

Julius Caesar was one of the earliest persons to employ cryptology in history.  All his correspondence from his campaigns to Rome were always encrypted by a very simple method, namely: every letter in his correspondence was transliterated to the next letter in the alphabet. I will provide you with the Introduction to his “Gallic Wars” book:

“All Gaul is divided into three parts, one of which the Belgae inhabit, the Aquitani another, those who in their own language are called Celts, in our Gauls, the third. Among the Helvetii, Orgetorix was by far the most distinguished and wealthy”

Answer 1

Program code:

#include<iostream>
using namespace std;

string Cypher;     //Declaring a string Cypher
int i=0;

string encrypt(string Cypher)      //Function to encrypt the string
{
    while(Cypher[i]!='\0')            //Iterates till the last character of string
    {
        Cypher[i]=Cypher[i]+1;      //Encrypting every character to the next character of alphabet.
        i++;                      
    }
    return Cypher;        //Returns encrypted string
}

string decrypt(string Cypher)   //Function to decrypt the string
{
    while(Cypher[i]!='\0')             //Iterates till the last character of string
    {
         Cypher[i]=Cypher[i]-1;     //Decrypting every character to the previous character of alphabet.
         i=i+1;
    }
    return Cypher;        //Returns decrypted string
}

int main()
{
    Cypher="All Gaul is divided into three parts, one of which the Belgae inhabit, the Aquitani another, those who in their own language are called Celts, in our Gauls, the third. Among the Helvetii, Orgetorix was by far the most distinguished and wealthy";    //Initializing string Cypher with the given string
    cout << "\nEncrypted String is:\n\n" << encrypt(Cypher);    //Printing encrypted string
    cout << "\n\nDecrypted String is:\n\n" << decrypt(Cypher);    //Printing decrypted string
}

Output:

NOTE:

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