// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
// 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.
package jodd.util;
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;
public class PBKDF2Hash {
public static final String PBKDF2_ALGORITHM = "PBKDF2WithHmacSHA1";
private final int saltBytes;
private final int hashBytes;
private final int pbkdf2Iterations;
public static final int ITERATION_INDEX = 0;
public static final int SALT_INDEX = 1;
public static final int PBKDF2_INDEX = 2;
public PBKDF2Hash() {
this(24, 24, 1000);
}
public PBKDF2Hash(int saltBytes, int hashBytes, int iterations) {
this.saltBytes = saltBytes;
this.hashBytes = hashBytes;
this.pbkdf2Iterations = iterations;
}
/**
* Returns a salted PBKDF2 hash of the password.
*
* @param password the password to hash
* @return a salted PBKDF2 hash of the password
*/
public String createHash(String password) {
return createHash(password.toCharArray());
}
/**
* Returns a salted PBKDF2 hash of the password.
*
* @param password the password to hash
* @return a salted PBKDF2 hash of the password
*/
public String createHash(char[] password) {
// Generate a random salt
SecureRandom random = new SecureRandom();
byte[] salt = new byte[saltBytes];
random.nextBytes(salt);
// Hash the password
byte[] hash = pbkdf2(password, salt, pbkdf2Iterations, hashBytes);
// format iterations:salt:hash
return pbkdf2Iterations + ":" + toHex(salt) + ":" + toHex(hash);
}
/**
* Validates a password using a hash.
*
* @param password the password to check
* @param goodHash the hash of the valid password
* @return true if the password is correct, false if not
*/
public boolean validatePassword(String password, String goodHash) {
return validatePassword(password.toCharArray(), goodHash);
}
/**
* Validates a password using a hash.
*
* @param password the password to check
* @param goodHash the hash of the valid password
* @return true if the password is correct, false if not
*/
public boolean validatePassword(char[] password, String goodHash) {
// Decode the hash into its parameters
String[] params = goodHash.split(":");
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, iterations, hash.length);
// Compare the hashes in constant time. The password is correct if
// both hashes match.
return slowEquals(hash, testHash);
}
/**
* Compares two byte arrays in length-constant time. This comparison method
* is used so that password hashes cannot be extracted from an on-line
* system using a timing attack and then attacked off-line.
*
* @param a the first byte array
* @param b the second byte array
* @return true if both byte arrays are the same, false if not
*/
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;
}
/**
* Computes the PBKDF2 hash of a password.
*
* @param password the password to hash.
* @param salt the salt
* @param iterations the iteration count (slowness factor)
* @param bytes the length of the hash to compute in bytes
* @return the PBDKF2 hash of the password
*/
private static byte[] pbkdf2(char[] password, byte[] salt, int iterations, int bytes) {
PBEKeySpec spec = new PBEKeySpec(password, salt, iterations, bytes * 8);
SecretKeyFactory skf = null;
try {
skf = SecretKeyFactory.getInstance(PBKDF2_ALGORITHM);
return skf.generateSecret(spec).getEncoded();
}
catch (NoSuchAlgorithmException ignore) {
return null;
}
catch (InvalidKeySpecException e) {
throw new IllegalArgumentException(e);
}
}
/**
* Converts a string of hexadecimal characters into a byte array.
*
* @param hex the hex string
* @return the hex string decoded into a byte array
*/
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), 16);
}
return binary;
}
/**
* Converts a byte array into a hexadecimal string.
*
* @param array the byte array to convert
* @return a length*2 character string encoding the byte array
*/
private static String toHex(byte[] array) {
BigInteger bi = new BigInteger(1, array);
String hex = bi.toString(16);
int paddingLength = (array.length * 2) - hex.length();
if (paddingLength > 0) {
return String.format("%0" + paddingLength + "d", Integer.valueOf(0)) + hex;
}
return hex;
}
}