Write a program for simple RSA algorithm to encrypt and decrypt the data.

import java.io.BufferedReader;

import java.io.FileReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.PrintWriter;

import java.net.InetAddress;

import java.net.ServerSocket;

import java.net.Socket;

import java.util.*;

public class RSA{

       public static void main(String[] args) {

             // TODO Auto-generated method stub

             Scanner s=new Scanner(System.in);

             RSA r=new RSA();

             System.out.println("Enter value for p");

             int p=s.nextInt();

             System.out.println("Enter value for q");

             int q=s.nextInt();

             int n=(p*q);

             int fai=((p-1)*(q=1));

              System.out.println("Enter value for e");

             int e=s.nextInt();

            

             while(true) {

                    if(GCD(fai,e)!=1) {

                           System.out.println("Enter value for e");

                           e=s.nextInt();

                    }

                    else

                           break;

             }

             int d=FindD(e,fai);

             System.out.println("Enter value for d="+d);

             System.out.println("Enter Message");

             int m=s.nextInt();

             int c=(int)(Math.pow(m,e)%n);

             System.out.println("Enter value for c="+c);

             int x=(int)(Math.pow(c,d)%n);

             System.out.println("Message at decription="+x);

             if(x==m) {

                    System.out.println("Matched");

             }

             else {

                    System.out.println("not Matched");

             }

       }

       static int FindD(int E,int Fai) {

             int s;

             for(int i=0;i<Fai;i++) {

                    s=(i*E)%Fai;

                    if(s==1) {

                           return i;

                    }

             }

             return 0;

       }

       static int GCD(int FAI,int EEE) {

             if(EEE==0) {

                    return FAI;

             }

             return GCD(EEE,FAI%EEE);

       }

}