CNS programs

 import java.util.Scanner;

public class CaesarCipher {

    // Method to encrypt text using Caesar Cipher

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

        StringBuilder encrypted = new StringBuilder();

        for (char character : text.toCharArray()) {

            if (Character.isLetter(character)) {

                char base = Character.isUpperCase(character) ? 'A' : 'a';

                char newChar = (char) ((character - base + shift) % 26 + base);

                encrypted.append(newChar);

            } else {

                encrypted.append(character); // Keep non-alphabetic characters as is

            }

        }

        return encrypted.toString();

    }

    // Method to decrypt text using Caesar Cipher

    public static String decrypt(String text, int shift) {

        return encrypt(text, 26 - (shift % 26)); // Reversing the shift

    }

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        System.out.println("Enter the text:");

        String text = scanner.nextLine();

        System.out.println("Enter the shift value:");

        int shift = scanner.nextInt();

        // Encrypt the text

        String encryptedText = encrypt(text, shift);

        System.out.println("Encrypted Text: " + encryptedText);

        // Decrypt the text

        String decryptedText = decrypt(encryptedText, shift);

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

        scanner.close();

    }

}