9Fz5SNaY

1import java.security.NoSuchAlgorithmException;
2import java.security.SecureRandom;
3import java.security.spec.InvalidKeySpecException;
4import java.util.Base64;
5
6import javax.crypto.SecretKey;
7import javax.crypto.SecretKeyFactory;
8import javax.crypto.spec.PBEKeySpec;
9
10public class Password {
11
12    private static final int DEFAULT_ITERATIONS = 100000;
13    private static final int DEFAULT_KEY_LENGTH = 512;
14    private static final int SALT_BYTE_LENGTH = 32;
15    private static final String KEY_DERIVATION_ALGORITHM = "PBKDF2WithHmacSHA512";
16    private static final String STORED_HASH_TEMPLATE = "%d$%d$%s$%s";
17
18    public static boolean matches(String password, String storedHash) {
19        String[] tokens = storedHash.split("\\$");
20
21        int iterations = Integer.parseInt(tokens[0]);
22        int keyLength = Integer.parseInt(tokens[1]);
23        byte[] salt = Base64.getDecoder().decode(tokens[2]);
24        String hash = tokens[3];
25
26        return matches(password, salt, hash, iterations, keyLength);
27    }
28
29    private static boolean matches(String password, byte[] salt, String hash, int iterations, int keyLength) {
30        return hash.equals(generate(password, salt, iterations, keyLength));
31    }
32
33    public static String generate(String password) {
34        byte[] salt = randomSalt();
35        String hash = generate(password, salt, DEFAULT_ITERATIONS, DEFAULT_KEY_LENGTH);
36        String base64Salt = Base64.getEncoder().encodeToString(salt);
37
38        return String.format(STORED_HASH_TEMPLATE, DEFAULT_ITERATIONS, DEFAULT_KEY_LENGTH, base64Salt, hash);
39    }
40
41    private static String generate(String password, byte[] salt, int iterations, int keyLength) {
42        try {
43            SecretKeyFactory skf = SecretKeyFactory.getInstance(KEY_DERIVATION_ALGORITHM);
44            PBEKeySpec spec = new PBEKeySpec(password.toCharArray(), salt, iterations, keyLength);
45            SecretKey key = skf.generateSecret(spec);
46
47            return Base64.getEncoder().encodeToString(key.getEncoded());
48
49        } catch (NoSuchAlgorithmException | InvalidKeySpecException e) {
50            throw new RuntimeException(e);
51        }
52    }
53
54    private static byte[] randomSalt() {
55        byte[] salt = new byte[SALT_BYTE_LENGTH];
56
57        SecureRandom r = new SecureRandom();
58        r.nextBytes(salt);
59        return salt;
60    }
61
62    public static void main(String[] args) {
63        String secret = "123456";
64        String hash = Password.generate(secret);
65        System.out.println(hash);
66        assert(Password.matches(secret, hash));
67        
68        String storedHash ="100000$512$Zzua/MrUuR2HHC6FkGejhg9DkUTaQFj8dXBCQDf3M38=$9zYltu2d2QLs"
69                + "lSYpl3voJAaNT9L/R4hiXbRWN9goSSt7nAcITu8JdniKRe1jDh35CWo9p2SSrlQnK6Le4ObveA==";
70        assert(Password.matches("hunter2", storedHash));
71    }
72
73}