对称密码的编程使用（DES、3DES、AES）

对称密码的概念

加密密钥和解密密钥相同，对于大多数对称密码算法，加解密过程互逆
加解密通信模型



特点：算法公开、计算量小、加密速度快、加密效率高
弱点：双方都使用同样密钥，安全性得不到保证

DES 算法的编程使用（密钥偏短（56位）、生命周期短）

package com.crypt.des;

import com.crypt.ByteToHexUtil;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
* des加密
* Created by zhangweixiang on 4/17/2016.
*/
public class DESUtil {

/**
* 生成desckey
* @param type
* @return
* @throws Exception
*/
public static byte[] generateKey(String type) throws Exception {
KeyGenerator keyGenerator = KeyGenerator.getInstance(type);
keyGenerator.init(56);
SecretKey secretKey = keyGenerator.generateKey();
return  secretKey.getEncoded();
}

/**
* 通过指定的deskey加密
* @param data 加密的数据
* @param key 秘钥
* @param type 加密方式
* @return 加密信息
* @throws Exception
*/
public static byte[] encrypt(byte[] data,byte[] key,String type) throws Exception {
SecretKey secretKey = new SecretKeySpec(key,type);
Cipher cipher = Cipher.getInstance(type);
cipher.init(Cipher.ENCRYPT_MODE,secretKey);
return cipher.doFinal(data);
}

/**
* des解密
* @param data 需要解密的数据
* @param key 解密秘钥
* @param type 类型
* @return 解密后的结果
* @throws Exception
*/
public static byte[] decrypt(byte[] data,byte[] key,String type) throws Exception {
SecretKey secretKey = new SecretKeySpec(key,type);
Cipher cipher = Cipher.getInstance(type);
cipher.init(Cipher.DECRYPT_MODE,secretKey);
return cipher.doFinal(data);
}

public static void main(String[] args) throws Exception {
String data = "test desc";
String type = "DES";// DES/ECB/PKCS5Padding
byte[] key = DESUtil.generateKey(type);
byte[] encData = DESUtil.encrypt(data.getBytes(),key,type);
String encDataStr = ByteToHexUtil.bytesToHexString(encData);
System.out.println(data+">>des encrypt>>"+encDataStr);

byte[] decData = DESUtil.decrypt(encData,key,type);
System.out.println(encDataStr+">>des decrypt>>"+new String(decData));
}
}

3DES 算法的编程使用

将密钥长度增至112位或168位，通过增加迭代次数提高安全性

缺点：处理速度较慢、密钥计算时间较长、加密效率不高

package com.crypt.des;

import com.crypt.ByteToHexUtil;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
* 3des加密
* Created by zhangweixiang on 4/17/2016.
*/
public class TripleDESUtils {

/**
* 生成3desckey
* @param type
* @return
* @throws Exception
*/
public static byte[] generateKey(String type) throws Exception {
KeyGenerator keyGenerator = KeyGenerator.getInstance(type);
keyGenerator.init(112);//128 168
SecretKey secretKey = keyGenerator.generateKey();
return  secretKey.getEncoded();
}

/**
* 通过指定的3deskey加密
* @param data 加密的数据
* @param key 秘钥
* @param type 加密方式
* @return 加密信息
* @throws Exception
*/
public static byte[] encrypt(byte[] data,byte[] key,String type) throws Exception {
SecretKey secretKey = new SecretKeySpec(key,type);
Cipher cipher = Cipher.getInstance(type);
cipher.init(Cipher.ENCRYPT_MODE,secretKey);
return cipher.doFinal(data);
}

/**
* 3des解密
* @param data 需要解密的数据
* @param key 解密秘钥
* @param type 类型
* @return 解密后的结果
* @throws Exception
*/
public static byte[] decrypt(byte[] data,byte[] key,String type) throws Exception {
SecretKey secretKey = new SecretKeySpec(key,type);
Cipher cipher = Cipher.getInstance(type);
cipher.init(Cipher.DECRYPT_MODE,secretKey);
return cipher.doFinal(data);
}

public static void main(String[] args) throws Exception {
String data = "test desc";
String type = "DESede";// DES/ECB/PKCS5Padding
byte[] key = TripleDESUtils.generateKey(type);
byte[] encData = TripleDESUtils.encrypt(data.getBytes(),key,type);
String encDataStr = ByteToHexUtil.bytesToHexString(encData);
System.out.println(data+">>3des encrypt>>"+encDataStr);

byte[] decData = TripleDESUtils.decrypt(encData,key,type);
System.out.println(encDataStr+">>3des decrypt>>"+new String(decData));
}
}

AES 算法的编程使用

1.AES：高级数据加密标准，能够有效抵御已知的针对DES算法的所有攻击

2.特点：密钥建立时间短、灵敏性好、内存需求低、安全性高

package com.crypt.des;

import com.crypt.ByteToHexUtil;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
* aes加密/解密
* Created by zhangweixiang on 4/17/2016.
*/
public class AESUtil {

/**
* 生成adesckey
* @param type
* @return
* @throws Exception
*/
public static byte[] generateKey(String type) throws Exception {
KeyGenerator keyGenerator = KeyGenerator.getInstance(type);
keyGenerator.init(128);//默认为128位，如果使用192 256则需获取无政策文件(从oracle官网下载UnlimitedJECPolicyJDK7解压后将
//其中的2个jar拷贝到jre下的lib下的security中即可 )
SecretKey secretKey = keyGenerator.generateKey();
return  secretKey.getEncoded();
}

/**
* 通过指定的aeskey加密
* @param data 加密的数据
* @param key 秘钥
* @param type 加密方式
* @return 加密信息
* @throws Exception
*/
public static byte[] encrypt(byte[] data,byte[] key,String type) throws Exception {
SecretKey secretKey = new SecretKeySpec(key,type);
Cipher cipher = Cipher.getInstance(type);
cipher.init(Cipher.ENCRYPT_MODE,secretKey);
return cipher.doFinal(data);
}

/**
* aes解密
* @param data 需要解密的数据
* @param key 解密秘钥
* @param type 类型
* @return 解密后的结果
* @throws Exception
*/
public static byte[] decrypt(byte[] data,byte[] key,String type) throws Exception {
SecretKey secretKey = new SecretKeySpec(key,type);
Cipher cipher = Cipher.getInstance(type);
cipher.init(Cipher.DECRYPT_MODE,secretKey);
return cipher.doFinal(data);
}

public static void main(String[] args) throws Exception {
String data = "test desc";
String type = "AES";//AES/ECB/PKCS5Padding
byte[] key = AESUtil.generateKey(type);
byte[] encData = AESUtil.encrypt(data.getBytes(),key,type);
String encDataStr = ByteToHexUtil.bytesToHexString(encData);
System.out.println(data+">>aes encrypt>>"+encDataStr);

byte[] decData = AESUtil.decrypt(encData,key,type);
System.out.println(encDataStr+">>aes decrypt>>"+new String(decData));
}
}