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1package com.makotojava.crypto;
2
3import javax.crypto.spec.*;
4import java.security.*;
5import javax.crypto.*;
6  
7public class Main
8{
9   static IvParameterSpec iv;
10  
11   public static void main(String []args) throws Exception {
12      String toEncrypt = "Send $10 dollars to Eva Georgieva";
13  
14      System.out.println("Encrypting...");
15      byte[] encrypted = encrypt(toEncrypt, "password");
16      //System.out.println("Encrypted text:" + encrypted);
17      System.out.println("Decrypting...");
18      String decrypted = decrypt(encrypted, "password");
19      //System.out.println("Decrypted text: " + decrypted);
20      System.out.println("Cut and paste: ");
21      cutAndPaste("Send $10 dollars to Eva Georgieva".getBytes());
22     
23   }
24  
25   public static void cutAndPaste(byte [] message) {
26	   byte [] modifiedMessage = message;
27	   byte b = 57;
28	   modifiedMessage[6] = b;
29	   System.out.println(new String(modifiedMessage));
30   }
31   public static byte[] encrypt(String toEncrypt, String key) throws Exception {
32      // create a binary key from the argument key (seed)
33      SecureRandom sr = new SecureRandom(key.getBytes());
34      KeyGenerator kg = KeyGenerator.getInstance("DES");
35      kg.init(sr);
36      SecretKey sk = kg.generateKey();
37  
38      // create an instance of cipher
39      Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
40  
41      // generate an initialization vector (IV)
42      SecureRandom secureRandom = new SecureRandom();
43      byte[] ivspec = new byte[cipher.getBlockSize()];
44      secureRandom.nextBytes(ivspec);
45      iv = new IvParameterSpec(ivspec);
46  
47      // initialize the cipher with the key and IV
48      cipher.init(Cipher.ENCRYPT_MODE, sk, iv);
49  
50      // encrypt!
51      byte[] encrypted = cipher.doFinal(toEncrypt.getBytes());
52  
53      return encrypted;
54   }
55  
56   public static String decrypt(byte[] toDecrypt, String key) throws Exception {
57      // create a binary key from the argument key (seed)
58      SecureRandom sr = new SecureRandom(key.getBytes());
59      KeyGenerator kg = KeyGenerator.getInstance("DES");
60      kg.init(sr);
61      SecretKey sk = kg.generateKey();
62  
63      // do the decryption with that key
64      Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
65      cipher.init(Cipher.DECRYPT_MODE, sk, iv);
66      byte[] decrypted = cipher.doFinal(toDecrypt);
67  
68      return new String(decrypted);
69   }
70}