PasswordHash.java

package com.dounine.corgi.security;

/*
 * Password Hashing With PBKDF2 (http://crackstation.net/hashing-security.htm).
 * Copyright (c) 2013, Taylor Hornby
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import java.math.BigInteger;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;

/**
 * PBKDF2 salted password hashing.
 * Author: havoc AT defuse.ca
 * www: http://crackstation.net/hashing-security.htm
 */
public class PasswordHash {
    public static final String PBKDF2_ALGORITHM = "PBKDF2WithHmacSHA1";

    // The following constants may be changed without breaking existing hashes.
    public static final int SALT_BYTE_SIZE = 24;
    public static final int HASH_BYTE_SIZE = 24;
    public static final int PBKDF2_ITERATIONS = 1000;

    // public static final int ITERATION_INDEX = 0;
    public static final int SALT_INDEX = 0;
    public static final int PBKDF2_INDEX = 1;
    private static final int BYTE_SIZE = 8;
    private static final int HEX_SIZE = 16;
    private static final String COLON = ":";

    public static String createHash(String password)
            throws NoSuchAlgorithmException, InvalidKeySpecException {
        return createHash(password.toCharArray());
    }

    public static String createHash(char[] password)
            throws NoSuchAlgorithmException, InvalidKeySpecException {
        // Generate a random salt
        SecureRandom random = new SecureRandom();
        byte[] salt = new byte[SALT_BYTE_SIZE];
        random.nextBytes(salt);

        // Hash the password
        byte[] hash = pbkdf2(password, salt, PBKDF2_ITERATIONS, HASH_BYTE_SIZE);
        // format salt:hash
        return toHex(salt) + COLON + toHex(hash);
    }

    public static boolean validatePassword(String password, String correctHash)
            throws NoSuchAlgorithmException, InvalidKeySpecException {
        return validatePassword(password.toCharArray(), correctHash);
    }

    public static boolean validatePassword(char[] password, String correctHash)
            throws NoSuchAlgorithmException, InvalidKeySpecException {
        // Decode the hash into its parameters
        String[] params = correctHash.split(COLON);
//        int iterations = Integer.parseInt(params[ITERATION_INDEX]);
        byte[] salt = fromHex(params[SALT_INDEX]);
        byte[] hash = fromHex(params[PBKDF2_INDEX]);
        // Compute the hash of the provided password, using the same salt,
        // iteration count, and hash length
        byte[] testHash = pbkdf2(password, salt, PBKDF2_ITERATIONS, hash.length);
        // Compare the hashes in constant time. The password is correct if
        // both hashes match.
        return slowEquals(hash, testHash);
    }

    private static boolean slowEquals(byte[] a, byte[] b) {
        int diff = a.length ^ b.length;
        for (int i = 0; i < a.length && i < b.length; i++){
            diff |= a[i] ^ b[i];
        }
        return diff == 0;
    }

    private static byte[] pbkdf2(char[] password, byte[] salt, int iterations, int bytes)
            throws NoSuchAlgorithmException, InvalidKeySpecException {
        PBEKeySpec spec = new PBEKeySpec(password, salt, iterations, bytes * BYTE_SIZE);
        SecretKeyFactory skf = SecretKeyFactory.getInstance(PBKDF2_ALGORITHM);
        return skf.generateSecret(spec).getEncoded();
    }

    private static byte[] fromHex(String hex) {
        byte[] binary = new byte[hex.length() / 2];
        for (int i = 0; i < binary.length; i++) {
            binary[i] = (byte) Integer.parseInt(hex.substring(2 * i, 2 * i + 2), HEX_SIZE);
        }
        return binary;
    }

    private static String toHex(byte[] array) {
        BigInteger bi = new BigInteger(1, array);
        String hex = bi.toString(HEX_SIZE);
        int paddingLength = (array.length * 2) - hex.length();
        if (paddingLength > 0){
            return String.format("%0" + paddingLength + "d", 0) + hex;
        }
        return hex;
    }

    public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeySpecException {
        System.out.println(createHash("123456"));
    }
}