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package javaapplication9;

import java.util.Scanner;

/**
 *
 * @author sjors
 */
public class JavaApplication9 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Scanner key = new Scanner(System.in);
        int Key = GenKey();
        int[] encrytedMessage;
        String Message, receivedMessage;
        System.out.println("The key used is: " + Key);
        System.out.println("message you whish to send:");
        Message = key.nextLine();
        System.out.println("Message before encryption: " + Message);
        encrytedMessage = Encrypt(Message, Key);
        System.out.println("Message after encryption: ");
        for(int i=0; i < encrytedMessage.length; i++){
            System.out.print(encrytedMessage[i]);

        }
        System.out.println();
        receivedMessage = Decrypt(encrytedMessage, Key);
        System.out.println("Decrypted message is: " + receivedMessage);
        }
    public static int GenKey(){
        double Key;
        do{
            Key = Math.random() * 9999;
        }while(Key < 1000 || Key % 2 == 0);//To ensure more safety on the encryption we make sure the random Key is above 1000, also we are making sure that the key is an odd number

        return (int) Key;

    }
    public static int[] Encrypt(String message, int Key){
        //First decode to message to numbers
        int encryptedMessage = 0;
        int length = message.length();
        int[] arrayMessage = new int[length];
        for (int i=0; i < length;i++){
            arrayMessage[i] = (int)message.charAt(i);
            //Encode each dataslot. add more operations(and more complicated operations) to increase security
            arrayMessage[i] *= Key;
        }
        return arrayMessage;

    }
    public static String Decrypt(int[] encryptedMessage, int Key){
        char[] decryptedMessage = new char[encryptedMessage.length];
        for (int i=0; i < encryptedMessage.length;i++){
            //Undo all the operations we did when we encrypted.
            encryptedMessage[i] /= Key;
            decryptedMessage[i] = (char)encryptedMessage[i];//cast int's back to chars
        }
        String str = String.valueOf(decryptedMessage);//return the array of chars into a string
        return str;
    }
}