/**
* Company Name : 中贸促信息技术有限责任公司
* Project Name:project
* File Name:PasswordHash.java
* Package Name:org.ccpit.base.utils
* Date:2015年10月23日下午2:10:48
* Copyright (c) 2015, dingwei@ccpit.org All Rights Reserved.
*
*/
package org.ccpit.base.utils;
import java.math.BigInteger;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
/**
* ClassName:PasswordHash <br/>
* Function: TODO ADD FUNCTION. <br/>
* Reason: TODO ADD REASON. <br/>
* Date: 2015年10月23日 下午2:10:48 <br/>
*
* @author dingwei
* @version
* @since JDK 1.6
* @see
*/
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 = 1;
public static final int PBKDF2_INDEX = 2;
/**
* Returns a salted PBKDF2 hash of the password.
*
* @param password
* the password to hash
* @return a salted PBKDF2 hash of the password
*/
public static String createHash(String password) throws NoSuchAlgorithmException, InvalidKeySpecException {
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 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 iterations:salt:hash
return PBKDF2_ITERATIONS + ":" + toHex(salt) + ":" + toHex(hash);
}
/**
* Validates a password using a hash.
*
* @param password
* the password to check
* @param correctHash
* the hash of the valid password
* @return true if the password is correct, false if not
*/
public static boolean validatePassword(String password, String correctHash)
throws NoSuchAlgorithmException, InvalidKeySpecException {
return validatePassword(password.toCharArray(), correctHash);
}
/**
* Validates a password using a hash.
*
* @param password
* the password to check
* @param correctHash
* the hash of the valid password
* @return true if the password is correct, false if not
*/
public static boolean validatePassword(char[] password, String correctHash)
throws NoSuchAlgorithmException, InvalidKeySpecException {
// Decode the hash into its parameters
String[] params = correctHash.split(":");
if (params.length <= 1) {
return false;
}
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) throws NoSuchAlgorithmException, InvalidKeySpecException {
PBEKeySpec spec = new PBEKeySpec(password, salt, iterations, bytes * 8);
SecretKeyFactory skf = SecretKeyFactory.getInstance(PBKDF2_ALGORITHM);
return skf.generateSecret(spec).getEncoded();
}
/**
* 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", 0) + hex;
else
return hex;
}
/**
* Tests the basic functionality of the PasswordHash class
*
* @param args
* ignored
*/
public static void main(String[] args) {
try {
// Print out 10 hashes
for (int i = 0; i < 10; i++)
System.out.println(PasswordHash.createHash("p\r\nassw0Rd!"));
// Test password validation
boolean failure = false;
System.out.println("Running tests...");
for (int i = 0; i < 100; i++) {
String password = "" + i;
String hash = createHash(password);
String secondHash = createHash(password);
if (hash.equals(secondHash)) {
System.out.println("FAILURE: TWO HASHES ARE EQUAL!");
failure = true;
}
String wrongPassword = "" + (i + 1);
if (validatePassword(wrongPassword, hash)) {
System.out.println("FAILURE: WRONG PASSWORD ACCEPTED!");
failure = true;
}
if (!validatePassword(password, hash)) {
System.out.println("FAILURE: GOOD PASSWORD NOT ACCEPTED!");
failure = true;
}
}
if (failure)
System.out.println("TESTS FAILED!");
else
System.out.println("TESTS PASSED!");
} catch (Exception ex) {
System.out.println("ERROR: " + ex);
}
}
}