对数据进行哈希加盐加密

介绍

哈希加盐是在对密码进行哈希加密的前提下，为了防止查表法对密码的暴力破解，因此需要对密码进行更强的加密，它利用的核心思想是在对真实密码进行加密前，首先生成一个随机的定长字符串，这个字符串就是所谓的“盐”，然后与真实密码连接起来进行哈希加密，这样查表法就不灵了，但我们需要额外的空间来记录这个盐值，为了后来解密需要
在进行密码验证时，需要先从数据库中获得对应的盐值，然后与输入的密码拼接起来进行哈希加密，最后与数据库存储的哈希加盐加密的字符串进行对比。

具体贴实现代码

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 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.     * 返回已加盐的PBKDF2哈希值     * 格式 迭代次数:盐值:哈希值     * @param password the password to hash     * @return a salted PBKDF2 hash of the password     */    public static String createPasswordHash(String password)throws NoSuchAlgorithmException, InvalidKeySpecException {        return createPasswordHash(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 createPasswordHash(char[] password)throws NoSuchAlgorithmException, InvalidKeySpecException {        byte[] salt=getSalt();        // 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.     * 验证密码     * @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(":");        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);    }    /**     * 生成盐值     * @return     * @throws NoSuchAlgorithmException     */    public static byte[] getSalt() throws NoSuchAlgorithmException    {        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");        byte[] salt = new byte[SALT_BYTE_SIZE];        sr.nextBytes(salt);        return salt;    }    //========================private method============================    /**     * 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;    }    /**     * 完成PBKDF2 加密密码     * @param password      密码     * @param salt the      盐值     * @param iterations    迭代次数(缓慢因子)     * @param bytes         hash（密钥）的字节长度     * @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();    }    /**     * 十六进制字符的字符串转换成字节数组。     *      * @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;    }    /**     * 将字节数组转换为十六进制字符串。     * @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;    }    public static void main(String[] args) {        String password="12345";        String salt;        try {            salt = getSalt().toString();            String hash=createPasswordHash(password);            System.out.println(hash);            long begin=System.currentTimeMillis();            System.out.println(validatePassword(password, hash));            System.out.println("time:"+(System.currentTimeMillis()-begin));        } catch (Exception e) {        }    }}