iG25LrGj

1package exercise1;
2
3import java.util.Arrays;
4import java.util.Scanner;
5import javax.crypto.Cipher;
6import javax.crypto.KeyGenerator;
7import javax.crypto.SecretKey;
8
9/**
10 *
11 * @author Lester
12 */
13public class des_encryption {
14
15    public static void main(String[] args) throws Exception {
16        Scanner in = new Scanner(System.in);
17        System.out.println("Hello User! ");
18        System.out.println("Please enter message 'No body can see me' to test out the DES Algorithm");
19        String UserInput = in.nextLine();
20        while (!"No body can see me".equals(UserInput)) {
21            System.out.println("Wrong text, enter the following text: No body can see me");
22            UserInput = in.nextLine();
23        }
24
25        SecretKey Destination_Key = desKeyGen();
26        byte[] encryptedMessage = desEncrypt(UserInput, Destination_Key);
27
28        System.out.println("The encrypted message is: ");
29        System.out.println(Arrays.toString(encryptedMessage));
30
31        String decryptedMessage = desDecrypt(encryptedMessage, Destination_Key);
32
33        System.out.println("The decrypted message is: ");
34        System.out.println(decryptedMessage);
35
36        in.close();
37    }
38
39    public static SecretKey desKeyGen() throws Exception {
40        KeyGenerator Keys = KeyGenerator.getInstance("DES");
41        SecretKey Destination_Key = Keys.generateKey();
42
43        return Destination_Key;
44    }
45
46    public static byte[] desEncrypt(String message, SecretKey Destination_Key) {
47        try {
48            byte[] byteMessage = message.getBytes("UTF8");
49
50            Cipher cipherDes = Cipher.getInstance("DES");
51            cipherDes.init(Cipher.ENCRYPT_MODE, Destination_Key);
52
53            byte[] encryptedMessage = cipherDes.doFinal(byteMessage);
54
55            return encryptedMessage;
56        } catch (Exception e) {
57            System.out.println(e);
58            return null;
59        }
60    }
61
62    public static String desDecrypt(byte[] encryptedMessage, SecretKey Destination_Key) {
63        try {
64            Cipher cipherDes = Cipher.getInstance("DES");
65            cipherDes.init(Cipher.DECRYPT_MODE, Destination_Key);
66
67            byte[] decryptedMessage = cipherDes.doFinal(encryptedMessage);
68
69            String plaintext = new String(decryptedMessage, "UTF-8");
70
71            return plaintext;
72        } catch (Exception e) {
73            System.out.println(e);
74            return null;
75        }
76
77    }
78
79}