mF9NexZ2

1package util.crypto;
2
3import java.io.IOException;
4import java.io.UnsupportedEncodingException;
5import java.security.AlgorithmParameters;
6import java.security.GeneralSecurityException;
7import java.security.NoSuchAlgorithmException;
8import java.security.spec.InvalidKeySpecException;
9import java.util.Base64;
10import javax.crypto.Cipher;
11import javax.crypto.SecretKey;
12import javax.crypto.SecretKeyFactory;
13import javax.crypto.spec.IvParameterSpec;
14import javax.crypto.spec.PBEKeySpec;
15import javax.crypto.spec.SecretKeySpec;
16
17
18/**
19 * User: rhmiller
20 * Date: 5/30/17
21 */
22public class ProtectedConfigFile {
23    public static void main(String[] args) throws Exception {
24        String password = System.getProperty("password");
25        if (password == null) {
26            throw new IllegalArgumentException("Run with -Dpassword=<password>");
27        }
28
29        // The salt (probably) can be stored along with the encrypted data
30        byte[] salt = "12345678".getBytes();
31
32        // Decreasing this speeds down startup time and can be useful during testing, but it also makes it easier for brute force attackers
33        int iterationCount = 40000;
34        // Other values give me java.security.InvalidKeyException: Illegal key size or default parameters
35        int keyLength = 128;
36        SecretKeySpec key = createSecretKey(System.getProperty("password").toCharArray(),
37                salt, iterationCount, keyLength);
38
39        String originalPassword = "secret";
40        System.out.println("Original password: " + originalPassword);
41        String encryptedPassword = encrypt(originalPassword, key);
42        System.out.println("Encrypted password: " + encryptedPassword);
43        String decryptedPassword = decrypt(encryptedPassword, key);
44        System.out.println("Decrypted password: " + decryptedPassword);
45    }
46
47    private static SecretKeySpec createSecretKey(char[] password, byte[] salt, int iterationCount, int keyLength) throws NoSuchAlgorithmException, InvalidKeySpecException {
48        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA512");
49        PBEKeySpec keySpec = new PBEKeySpec(password, salt, iterationCount, keyLength);
50        SecretKey keyTmp = keyFactory.generateSecret(keySpec);
51        return new SecretKeySpec(keyTmp.getEncoded(), "AES");
52    }
53
54    private static String encrypt(String property, SecretKeySpec key) throws GeneralSecurityException, UnsupportedEncodingException {
55        Cipher pbeCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
56        pbeCipher.init(Cipher.ENCRYPT_MODE, key);
57        AlgorithmParameters parameters = pbeCipher.getParameters();
58        IvParameterSpec ivParameterSpec = parameters.getParameterSpec(IvParameterSpec.class);
59        byte[] cryptoText = pbeCipher.doFinal(property.getBytes("UTF-8"));
60        byte[] iv = ivParameterSpec.getIV();
61        return base64Encode(iv) + ":" + base64Encode(cryptoText);
62    }
63
64    private static String base64Encode(byte[] bytes) {
65        return Base64.getEncoder().encodeToString(bytes);
66    }
67
68    private static String decrypt(String string, SecretKeySpec key) throws GeneralSecurityException, IOException {
69        String iv = string.split(":")[0];
70        String property = string.split(":")[1];
71        Cipher pbeCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
72        pbeCipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(base64Decode(iv)));
73        return new String(pbeCipher.doFinal(base64Decode(property)), "UTF-8");
74    }
75
76    private static byte[] base64Decode(String property) throws IOException {
77        return Base64.getDecoder().decode(property);
78    }
79}