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;
public abstract class PBECoder
extends Coder {
public static final String ALGORITHM =
"PBEWITHMD5andDES";
public static byte[] initSalt()
throws Exception {
byte[] salt =
new byte[
8]; Random random =
new Random(); random.nextBytes(salt);
return salt; }
private static Key toKey(String password)
throws Exception { PBEKeySpec keySpec =
new PBEKeySpec(password.toCharArray()); SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM); SecretKey secretKey = keyFactory.generateSecret(keySpec);
return secretKey; }
public static byte[] encrypt(
byte[] data, String password,
byte[] salt)
throws Exception { 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); }
public static byte[] decrypt(
byte[] data, String password,
byte[] salt)
throws Exception { 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
*
* @author 梁栋
* @version 1.0
* @since 1.0
*/
public abstract class PBECoder extends Coder {
/**
* 支持以下任意一种算法
*
* <pre>
* PBEWithMD5AndDES
* PBEWithMD5AndTripleDES
* PBEWithSHA1AndDESede
* PBEWithSHA1AndRC2_40
* </pre>
*/
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<br>
*
* @param password
* @return
* @throws Exception
*/
private static Key toKey(String password) throws Exception {
PBEKeySpec keySpec = new PBEKeySpec(password.toCharArray());
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);
SecretKey secretKey = keyFactory.generateSecret(keySpec);
return secretKey;
}
/**
* 加密
*
* @param data
* 数据
* @param password
* 密码
* @param salt
* 盐
* @return
* @throws Exception
*/
public static byte[] encrypt(byte[] data, String password, byte[] salt)
throws Exception {
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 password
* 密码
* @param salt
* 盐
* @return
* @throws Exception
*/
public static byte[] decrypt(byte[] data, String password, byte[] salt)
throws Exception {
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;
/**
*
* @author 梁栋
* @version 1.0
* @since 1.0
*/
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。
