RnXXm81z

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 network_security;
7
8import java.io.UnsupportedEncodingException;
9import java.security.InvalidKeyException;
10import java.security.MessageDigest;
11import java.security.NoSuchAlgorithmException;
12import java.security.SecureRandom;
13import java.security.spec.KeySpec;
14import java.util.Arrays;
15import java.util.Base64;
16import javax.crypto.BadPaddingException;
17import javax.crypto.Cipher;
18import javax.crypto.IllegalBlockSizeException;
19import javax.crypto.KeyGenerator;
20import javax.crypto.NoSuchPaddingException;
21import javax.crypto.SecretKey;
22import javax.crypto.SecretKeyFactory;
23import javax.crypto.spec.PBEKeySpec;
24import javax.crypto.spec.SecretKeySpec;
25
26/**
27 *
28 * @author Admin
29 */
30public class SymmetricCryptor {
31
32    //hằng xác định thuật toán mã hóa
33    private final String Algorithm = "AES";
34    //khóa
35    private SecretKey secretKey;
36    //bộ sinh khóa theo thuật toán đã chọn
37    private KeyGenerator keyGen;
38    //bộ mã
39    private Cipher cipher;
40
41    public SymmetricCryptor() {
42
43    }
44
45    // Tạo khóa không sử dụng chuỗi
46    public void createSymetricKey() throws Exception {
47        //khởi tạo bộ sinh khóa
48        keyGen = KeyGenerator.getInstance(Algorithm);
49        //sinh khóa
50        secretKey = keyGen.generateKey();
51    }
52
53    // Tạo khóa sử dụng chuỗi
54    public void createSymetricKeyFromPassword(String keystring) throws Exception {
55        byte[] key = new byte[16];
56        key = keystring.getBytes("UTF-8");
57        MessageDigest sha = MessageDigest.getInstance("SHA-1");
58        key = sha.digest(key);
59        key = Arrays.copyOf(key, 16);
60
61        secretKey = new SecretKeySpec(key, "AES");
62    }
63
64    public SecretKey getSecretKey() {
65        return secretKey;
66    }
67
68    public String encryptText(String msg, SecretKey key)
69            throws Exception {
70        //tạo bộ mã
71        cipher = Cipher.getInstance(Algorithm);
72        cipher.init(Cipher.ENCRYPT_MODE, key);
73        return Base64.getEncoder().encodeToString(
74                cipher.doFinal(msg.getBytes("UTF-8")));
75    }
76
77    public String decryptText(String msg, SecretKey key)
78            throws Exception {
79        cipher = Cipher.getInstance(Algorithm);
80        cipher.init(Cipher.DECRYPT_MODE, key);
81        return new String(cipher.doFinal(
82                Base64.getDecoder().decode(msg)), "UTF-8");
83    }
84    
85    public static void main(String[] args) throws Exception {
86        SymmetricCryptor SC = new SymmetricCryptor();
87        SC.createSymetricKeyFromPassword("daicaphong");
88        String msg = "Nguyễn Văn An";
89        String encrypted_msg = 
90                SC.encryptText(msg, SC.getSecretKey());
91        System.out.println("Plain text: " + msg);
92        System.out.println("Encrypted text: " + encrypted_msg);
93        String decrypted_msg =
94                SC.decryptText(encrypted_msg, SC.getSecretKey());
95        System.out.println("Decrypted text: " + decrypted_msg);
96    }
97}