import java.util.Scanner; import java.util.Scanner; public class Encr { public static final String ALPHABET = "abcdefghijklmnopqrstuvwxyz"; public static String encrypt(String plainText, int shiftKey) { plainText = plainText.toLowerCase(); String cipherText = ""; for (int i = 0; i < plainText.length(); i++) { int charPosition = ALPHABET.indexOf(plainText.charAt(i)); int keyVal = (shiftKey + charPosition) % 26; char replaceVal = ALPHABET.charAt(keyVal); cipherText += replaceVal; } return cipherText; } public static String decrypt(String cipherText, int shiftKey) { cipherText = cipherText.toLowerCase(); String plainText = ""; for (int i = 0; i < cipherText.length(); i++) { int charPosition = ALPHABET.indexOf(cipherText.charAt(i)); int keyVal = (charPosition - shiftKey) % 26; if (keyVal < 0) { keyVal = ALPHABET.length() + keyVal; } char replaceVal = ALPHABET.charAt(keyVal); plainText += replaceVal; } return plainText; } public static void main(String[] args) { Scanner sc = new Scanner(System.in); System.out.println("Enter the String for Encryption: "); String message = new String(); message = sc.next(); System.out.println(encrypt(message, 3)); System.out.println(decrypt(encrypt(message, 3), 3)); sc.close(); } }