安全 PBE

• 在之前的文章中曾講到過DES加密算法，類似這種加密算法都有一個(gè)密鑰，密鑰的長度決定了加密的安全性，但是這種密鑰比較難記憶，是需要存儲(chǔ)的。
• PBE算法是一種基于口令的加密算法，它并不是構(gòu)建了一種新的加解密算法，而是對(duì)比如DES這樣的算法進(jìn)行了包裝，采用隨機(jī)數(shù)加口令的方式保證數(shù)據(jù)的安全。
• 在PBE算法中有口令一說，相當(dāng)于我們記憶的密碼，但是口令的長度以及安全性是有限的，所以這時(shí)需要采用隨機(jī)數(shù)附加在口令上通過消息摘要算法經(jīng)過迭代產(chǎn)生密鑰。
• 使破譯的難度加大。常用的PBE算法有PBEWITHMD5andDES。

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.util.Arrays;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

import junit.framework.TestCase;

public class PBETest extends TestCase {
    
    /** 算法 */
    public static final String ALGORITHM = "PBEWITHMD5andDES";
    /** 迭代次數(shù) */
    public static int ITERAT_COUNT = 100;

    /**
     * 構(gòu)造一個(gè)8位的鹽
     * @return
     */
    private byte[] initSalt() {
        SecureRandom random = new SecureRandom();
        return random.generateSeed(8);
    }
    
    /**
     * 生成口令的Key
     * @param password
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */
    private Key getKey(String password) throws NoSuchAlgorithmException, InvalidKeySpecException {
        PBEKeySpec spec = new PBEKeySpec(password.toCharArray());
        SecretKeyFactory factory = SecretKeyFactory.getInstance(ALGORITHM);
        return factory.generateSecret(spec);
    }
    
    /**
     * 加密
     * @param password
     * @param salt
     * @param data
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     * @throws NoSuchPaddingException
     * @throws InvalidKeyException
     * @throws InvalidAlgorithmParameterException
     * @throws IllegalBlockSizeException
     * @throws BadPaddingException
     */
    public byte[] encript(String password, byte[] salt, byte[] data) 
            throws NoSuchAlgorithmException, InvalidKeySpecException, 
            NoSuchPaddingException, InvalidKeyException,  BadPaddingException, 
            InvalidAlgorithmParameterException, IllegalBlockSizeException {
        Key key  = this.getKey(password);
        //實(shí)例化PBE參數(shù)材料
        PBEParameterSpec params = new PBEParameterSpec(salt, ITERAT_COUNT);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, key, params);
        return cipher.doFinal(data);
    }
    
    /**
     * 解密
     * @param password
     * @param salt
     * @param data
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     * @throws NoSuchPaddingException
     * @throws InvalidKeyException
     * @throws InvalidAlgorithmParameterException
     * @throws IllegalBlockSizeException
     * @throws BadPaddingException
     */
    public byte[] decript(String password, byte[] salt, byte[] data)
            throws NoSuchAlgorithmException, InvalidKeySpecException, 
            NoSuchPaddingException, InvalidKeyException, BadPaddingException, 
            InvalidAlgorithmParameterException, IllegalBlockSizeException {
        Key key  = this.getKey(password);
        //實(shí)例化PBE參數(shù)材料
        PBEParameterSpec params = new PBEParameterSpec(salt, ITERAT_COUNT);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, key, params);
        return cipher.doFinal(data);
    }
    
    public void test() throws Exception{
        String data = "需要處理的數(shù)據(jù)";
        String password = "123456";
        byte[] salt = this.initSalt();
        byte[] cryptograph = this.encript(password, salt, data.getBytes("GBK"));
        byte[] newData = this.decript(password, salt, cryptograph);
        
        System.out.println(data);
        System.out.println(Arrays.toString(cryptograph));
        System.out.println(new String(newData, "GBK"));
    }
}