import java.math.BigInteger;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
public class PasswordEncryption {
public static final String PBKDF2_ALGORITHM = "PBKDF2WithHmacSHA1";
/**
* 盐的长度
*/
public static final int SALT_BYTE_SIZE = 32 / 2;
/**
* 生成密文的长度
*/
public static final int HASH_BIT_SIZE = 128 * 4;
/**
* 迭代次数
*/
public static final int PBKDF2_ITERATIONS = 1000;
/**
* 对输入的password进行验证
*
* @param attemptedPassword 待验证的password
* @param encryptedPassword 密文
* @param salt 盐值
* @return 是否验证成功
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
*/
public static boolean authenticate(String attemptedPassword, String encryptedPassword, String salt)
throws NoSuchAlgorithmException, InvalidKeySpecException {
// 用同样的盐值对用户输入的password进行加密
String encryptedAttemptedPassword = getEncryptedPassword(attemptedPassword, salt);
// 把加密后的密文和原密文进行比較，同样则验证成功。否则失败
return encryptedAttemptedPassword.equals(encryptedPassword);
}
/**
* 生成密文
*
* @param password 明文password
* @param salt 盐值
* @return
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
*/
public static String getEncryptedPassword(String password, String salt) throws NoSuchAlgorithmException,
InvalidKeySpecException {
KeySpec spec = new PBEKeySpec(password.toCharArray(), fromHex(salt), PBKDF2_ITERATIONS, HASH_BIT_SIZE);
SecretKeyFactory f = SecretKeyFactory.getInstance(PBKDF2_ALGORITHM);
return toHex(f.generateSecret(spec).getEncoded());
}
/**
* 通过提供加密的强随机数生成器 生成盐
*
* @return
* @throws NoSuchAlgorithmException
*/
public static String generateSalt() throws NoSuchAlgorithmException {
SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
byte[] salt = new byte[SALT_BYTE_SIZE];
random.nextBytes(salt);
return toHex(salt);
}
/**
* 十六进制字符串转二进制字符串
*
* @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;
}
/**
* 二进制字符串转十六进制字符串
*
* @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;
}
}