JAVA加密算法3

除了DES，我们还知道有DESede(TripleDES,就是3DES)、AES、Blowfish、RC2、RC4(ARCFOUR)等多种对称加密方式，其实现方式大同小异，这里介绍对称加密的另一个算法——PBE

PBE
    PBE——Password-based encryption（基于密码的验证）。其特点在于口令由用户自己掌管，不借助任何物理媒体；采用随机数（这里我们叫做盐）杂凑多重加密等方法保证数据的安全性。是一种简便的加密方式。

通过java代码实现如下：Coder类见 java加密技术（一）
Java代码
import java.security.Key;  
import java.util.Random;  
 
import javax.crypto.Cipher;  
import javax.crypto.SecretKey;  
import javax.crypto.SecretKeyFactory;  
import javax.crypto.spec.PBEKeySpec;  
import javax.crypto.spec.PBEParameterSpec;  
 
/** 
* PBE安全编码组件 
*  
*/ 
public abstract class PBECoder extends Coder {  
    public static final String ALGORITHM = "PBEWITHMD5andDES";  
 
    /** 
     * 盐初始化 
     *  
     * @return 
     * @throws Exception 
     */ 
    public static byte[] initSalt() throws Exception {  
        byte[] salt = new byte[8];  
        Random random = new Random();  
        random.nextBytes(salt);  
        return salt;  
    }  
 
    /** 
     * 转换密钥
 
     *  
     * @param key 
     * @return 
     * @throws Exception 
     */ 
    private static Key toKey(char[] key) throws Exception {  
        PBEKeySpec keySpec = new PBEKeySpec(key);  
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);  
        SecretKey secretKey = keyFactory.generateSecret(keySpec);  
 
        return secretKey;  
    }  
 
    /** 
     * 加密 
     *  
     * @param data 
     *            数据 
     * @param pwd 
     *            密码 
     * @param salt 
     *            盐 
     * @return 
     * @throws Exception 
     */ 
    public static byte[] encrypt(byte[] data, String pwd, byte[] salt)  
            throws Exception {  
        char[] password = pwd.toCharArray();  
 
        Key key = toKey(password);  
 
        PBEParameterSpec paramSpec = new PBEParameterSpec(salt, 100);  
        Cipher cipher = Cipher.getInstance(ALGORITHM);  
        cipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);  
 
        return cipher.doFinal(data);  
 
    }  
 
    /** 
     * 解密 
     *  
     * @param data 
     *            数据 
     * @param pwd 
     *            密码 
     * @param salt 
     *            盐 
     * @return 
     * @throws Exception 
     */ 
    public static byte[] decrypt(byte[] data, String pwd, byte[] salt)  
            throws Exception {  
        char[] password = pwd.toCharArray();  
 
        Key key = toKey(password);  
 
        PBEParameterSpec paramSpec = new PBEParameterSpec(salt, 100);  
        Cipher cipher = Cipher.getInstance(ALGORITHM);  
        cipher.init(Cipher.DECRYPT_MODE, key, paramSpec);  
 
        return cipher.doFinal(data);  
 
    }  
} 

import java.security.Key;
import java.util.Random;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

/**
* PBE安全编码组件
*
*/
public abstract class PBECoder extends Coder {
public static final String ALGORITHM = "PBEWITHMD5andDES";

/**
* 盐初始化
*
* @return
* @throws Exception
*/
public static byte[] initSalt() throws Exception {
byte[] salt = new byte[8];
Random random = new Random();
random.nextBytes(salt);
return salt;
}

/**
* 转换密钥

*
* @param key
* @return
* @throws Exception
*/
private static Key toKey(char[] key) throws Exception {
PBEKeySpec keySpec = new PBEKeySpec(key);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);
SecretKey secretKey = keyFactory.generateSecret(keySpec);

return secretKey;
}

/**
* 加密
*
* @param data
*            数据
* @param pwd
*            密码
* @param salt
*            盐
* @return
* @throws Exception
*/
public static byte[] encrypt(byte[] data, String pwd, byte[] salt)
throws Exception {
char[] password = pwd.toCharArray();

Key key = toKey(password);

PBEParameterSpec paramSpec = new PBEParameterSpec(salt, 100);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);

return cipher.doFinal(data);

}

/**
* 解密
*
* @param data
*            数据
* @param pwd
*            密码
* @param salt
*            盐
* @return
* @throws Exception
*/
public static byte[] decrypt(byte[] data, String pwd, byte[] salt)
throws Exception {
char[] password = pwd.toCharArray();

Key key = toKey(password);

PBEParameterSpec paramSpec = new PBEParameterSpec(salt, 100);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, key, paramSpec);

return cipher.doFinal(data);

}
}


再给出一个测试类：
Java代码
import static org.junit.Assert.*;  
 
import org.junit.Test;  
 
/** 
*  
*/ 
public class PBECoderTest {  
 
    @Test 
    public void test() throws Exception {  
        String inputStr = "abc";  
        System.err.println("原文: " + inputStr);  
        byte[] input = inputStr.getBytes();  
 
        String pwd = "efg";  
        System.err.println("密码: " + pwd);  
 
        byte[] salt = PBECoder.initSalt();  
 
        byte[] data = PBECoder.encrypt(input, pwd, salt);  
 
        System.err.println("加密后: " + PBECoder.encryptBASE64(data));  
 
        byte[] output = PBECoder.decrypt(data, pwd, salt);  
        String outputStr = new String(output);  
 
        System.err.println("解密后: " + outputStr);  
        assertEquals(inputStr, outputStr);  
    }  
 
} 

import static org.junit.Assert.*;

import org.junit.Test;

/**
*
*/
public class PBECoderTest {

@Test
public void test() throws Exception {
String inputStr = "abc";
System.err.println("原文: " + inputStr);
byte[] input = inputStr.getBytes();

String pwd = "efg";
System.err.println("密码: " + pwd);

byte[] salt = PBECoder.initSalt();

byte[] data = PBECoder.encrypt(input, pwd, salt);

System.err.println("加密后: " + PBECoder.encryptBASE64(data));

byte[] output = PBECoder.decrypt(data, pwd, salt);
String outputStr = new String(output);

System.err.println("解密后: " + outputStr);
assertEquals(inputStr, outputStr);
}

}


控制台输出：
Console代码
原文: abc  
密码: efg  
加密后: iCZ0uRtaAhE=  
 
解密后: abc 

原文: abc
密码: efg
加密后: iCZ0uRtaAhE=

解密后: abc

    后续我们会介绍非对称加密算法，如RSA、DSA、DH、ECC等。