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1/*
2 * To change this license header, choose License Headers in Project Properties.
3 * To change this template file, choose Tools | Templates
4 * and open the template in the editor.
5 */
6package javaapplication3;
7
8import java.io.*;
9import java.security.InvalidKeyException;
10import java.security.*;
11 
12import javax.crypto.BadPaddingException;
13import javax.crypto.Cipher;
14import javax.crypto.IllegalBlockSizeException;
15import javax.crypto.NoSuchPaddingException;
16import javax.crypto.spec.SecretKeySpec;
17 
18/**
19 * A utility class that encrypts or decrypts a file. 
20 * @author www.codejava.net
21 *
22 */
23public class CryptoUtils {
24 
25    public static byte[] encrypt(String ALGORITHM, String key, byte[] inputBytes)
26            throws CryptoException {
27        
28        if(ALGORITHM.equals("AES") || ALGORITHM.equals("Blowfish")){
29            if(key.length()>16)
30                key = key.substring(0,16);
31            else if(key.length()<16)
32                key = key + key.substring(0, 16-key.length() );
33        }
34        else if(ALGORITHM.equals("DES")){
35            if(key.length()>8)
36                key = key.substring(0,8);
37            else if(key.length()<8)
38                key = key + key.substring(0, 8-key.length() );
39            
40        }
41        
42        return doCrypto(ALGORITHM, Cipher.ENCRYPT_MODE, key, inputBytes);
43    }
44 
45    public static byte[] decrypt(String ALGORITHM, String key, byte[] inputBytes)
46            throws CryptoException {
47        
48        if(ALGORITHM.equals("AES") || ALGORITHM.equals("Blowfish")){
49            if(key.length()>16)
50                key = key.substring(0,16);
51            if(key.length()<16)
52                key = key + key.substring(0, 16-key.length() );
53        }
54        else if(ALGORITHM.equals("DES")){
55            if(key.length()>8)
56                key = key.substring(0,8);
57            else if(key.length()<8)
58                key = key + key.substring(0, 8-key.length() );
59            
60        }
61        return doCrypto(ALGORITHM, Cipher.DECRYPT_MODE, key, inputBytes);
62    }
63    
64    
65    public static byte[] encryptRSA(PublicKey publicKey, String message) throws Exception {
66        Cipher cipher = Cipher.getInstance("RSA");  
67        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
68        return cipher.doFinal(message.getBytes());  
69    }
70
71    
72
73    public static byte[] decryptRSA(PrivateKey privateKey, byte [] encrypted) throws Exception {
74        Cipher cipher = Cipher.getInstance("RSA");
75        cipher.init(Cipher.DECRYPT_MODE, privateKey);
76        return cipher.doFinal(encrypted);
77    }
78 
79    private static byte[] doCrypto(String ALGORITHM, int cipherMode, String key, byte[] inputBytes) throws CryptoException {
80        try {
81            
82            
83            Key secretKey = new SecretKeySpec(key.getBytes(), ALGORITHM);
84            Cipher cipher = Cipher.getInstance(ALGORITHM);
85            cipher.init(cipherMode, secretKey);
86            
87             
88            byte[] outputBytes = cipher.doFinal(inputBytes);
89             
90            return outputBytes;
91             
92        } catch (NoSuchPaddingException | NoSuchAlgorithmException
93                | InvalidKeyException | BadPaddingException
94                | IllegalBlockSizeException ex) {
95            
96        }
97        
98        
99        return null;
100    }
101
102    public class CryptoException extends Exception {
103 
104    public CryptoException() {
105    }
106 
107    public CryptoException(String message, Throwable throwable) {
108        super(message, throwable);
109    }
110}
111}