Java Program:
package ceasercipher;
/**
*
* @author MAXHUB
*/
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;
public class CeaserCipher {
static Scanner sc=new Scanner(System.in);
static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
public static void main(String[] args) throws IOException{
// TODO code application logic here
System.out.print("Enter any String:");
String str =br.readLine();
System.out.print("\nEntertheKey:"); int
key =sc.nextInt();
String encrypted = encrypt(str, key);
System.out.println("\nEncryptedString is:"+encrypted);
String decrypted = decrypt(encrypted, key);
System.out.println("\nDecryptedString is:"+decrypted);
System.out.println("\n");
}
public static String encrypt(String str,int key)
{
String encrypted ="";
for(int i = 0; i < str.length(); i++)
{
int c=str.charAt(i);
if (Character.isUpperCase(c)) {
c = c + (key % 26);if (c > 'Z')
c = c - 26;
}
else if (Character.isLowerCase(c))
{
c = c + (key % 26);
if (c > 'z')
c = c - 26;
}
encrypted += (char) c;
}
return encrypted;
}
public static String decrypt(String str,int key)
{
String decrypted ="";
for(int i = 0; i<str.length(); i++)
{
int c = str.charAt(i);
if (Character.isUpperCase(c))
{
c = c - (key % 26);
if (c < 'A')
c = c + 26;
}
else if (Character.isLowerCase(c))
{
c = c - (key % 26);
if(c < 'a')
c= c+26;
}f
decrypted += (char) c;
}
return decrypted;
}
}
Sample Run:
