Caesar Cipher Algo

Algorithm of Caesar Cipher

Caesar Cipher Technique is the simple and easy method of encryption technique. It is simple type of substitution cipher. Each letter of plain text is replaced by a letter with some fixed number of positions down with alphabet.

package clg.Cypto.assignment;

import java.util.Scanner;

public class CaesarCipher {

// Encrypts text using shift

public static StringBuffer encrypt(String text, int shift) {

StringBuffer result = new StringBuffer();

for (int i = 0; i < text.length(); i++) {

if (Character.isUpperCase(text.charAt(i))) {

char ch = (char) (((int) text.charAt(i) + shift - 65) % 26 + 65);

result.append(ch);

} else {

char ch = (char) (((int) text.charAt(i) + shift - 97) % 26 + 97);

result.append(ch);

}

}

return result;

}

// Decrypts cipher using shift

public static StringBuffer decrypt(String cipher, int shift) {

StringBuffer result = new StringBuffer();

for (int i = 0; i < cipher.length(); i++) {

if (Character.isUpperCase(cipher.charAt(i))) {

char ch = (char) (((int) cipher.charAt(i) + shift - 65) % 26 + 65);

result.append(ch);

} else {

char ch = (char) (((int) cipher.charAt(i) + shift - 97) % 26 + 97);

result.append(ch);

}

}

return result;

}

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

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

String msg = sc.nextLine();

System.out.println("Enter position how many charecter shift");

int k = sc.nextInt();

System.out.println("**********************************************");

System.out.println("Encryption");

System.out.println("Text  : " + msg);

System.out.println("Shift : " + k);

String cipher = encrypt(msg, k).toString();

System.out.println("Encrypted Cipher: " + cipher);

System.out.println("Decryption");

System.out.println("Encrypted Cipher: " + cipher);

System.out.println("Shift : " + k);

String decrypted = decrypt(cipher, 26 - k).toString();

System.out.println("Decrypted Plain Text  : " + decrypted);

System.out.println("*********************************************");

sc.close();

}

}

=========================================================================

OUTPUT:

Enter Massager

VIKAHSKARMA

Enter position how many charecter shift

3

**********************************************

Encryption

Text  : VIKAHSKARMA

Shift : 3

Encrypted Cipher: YLNDKVNDUPD

Decryption

Encrypted Cipher: YLNDKVNDUPD

Shift : 3

Decrypted Plain Text  : VIKAHSKARMA

*********************************************

Caesar Cipher