JAVA PROGRAMMING : Alice recently read the news about Edward Snowden, and learne

Question

JAVA PROGRAMMING : Alice recently read the news about Edward Snowden, and learned that encryption could be used to
protect personal communication effectively. She decided to construct a simple encryption scheme to
protect her own communications as follows. First, she generates a set of randomly chosen "secret keys"
K1, K2, K3. Next, using these keys, she encrypts a set of messages M1, M2, M3, obtaining ciphertexts
C1= K1 + M1, C2= K2+ M2, C3 =K3+M3.
In implementing her scheme, she decides to choose the secret keys from the set A={1, 2, ..., 100}, and
the messages from the sequence B=(a, b, c, ..., z). She is adamant that her ciphertexts should also be
elements of the sequence B; to this end, she defines the "+" operator in expressions such as C1=K1+M1
to shift element M1 in B to the right by K1 positions. For example, if K1=1 and M1= b, then the
corresponding ciphertext is C1= c. Similarly, if K1=2 and M1=b, then the ciphertext is C1=d, if K1=24 and
M1=b, the ciphertext is C1=z, and if K1=25 and M1=b, then the ciphertext is C1=a.

Requirements:
1. the file name must named as Problem2.java
2. a static method:
public static String encryptMessage(int[] secretKeys, String message)

Input
The input consists of four rows.
a. The first row is an integer n satisfying 1 <= n <= 100 specifying the number of secret keys.
b. The second row is a sequence of n integers, each from the set A={1,2,..,100}, corresponding to the secret keys.
c. The third row is a sequence of symbols from the set B={a,b,..,z} corresponding to the messaged to be encrypted.
d. The fourth row is a special value -1 to indicate the end of the input phase.

Output
Output a single row of symbols from set B corresponding to each of the ciphertexts.

Sample Input
3
1 2 3
bzy
-1

Sample Output
cbb

Explanation / Answer

import java.io.*;
import java.util.Scanner;
class Problem2
{
   public static void main(String[] args)
   {
       int n,num;
       char alpha;
       Scanner read=new Scanner(System.in);
       System.out.println("enter no. of secret keys u want...");
       n=read.nextInt();//no. of secret keys
       read.nextLine();//to print new line
       int arr[]=new int[n];
       System.out.println("Enter the Integers");//Each integer specifies the number of times the corresponding //message character should incremented
       for(int i=0;i<n;i++)
       {
           arr[i]=read.nextInt();
           if(arr[i]<1||arr[i]>100)
           {
           System.out.println("Invalid inputs...try again");
           System.exit(0);
           }
           if(i==n-1)
               read.nextLine();
       }
       char msg[]=new char[n];
       System.out.println("Enter the message characters"); // actual message charaters
       for(int i=0;i<n;i++)
       {
           msg[i]=read.next().charAt(0);
       }
  
       for(int i=0;i<n;i++)
       {
           num=arr[i];
           alpha=msg[i];
           while(num!=0)
           {
               if(msg[i]!='z')
               {
                   msg[i]++;
                   num--;
               }
               else
               {
                   msg[i]='a';
                   num--;
               }
           }
       }
       for(int i=0;i<n;i++) //output secret message
           System.out.print(msg[i]);
   }
}

sample output:

enter no. of secret keys u want...
3
Enter the Integers
1 2 3
Enter the message characters
b z y
cbb

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