/**
* @(#)DESEncryption.java 2013-08-03
* CopyRight
*/
package com.first.encryption;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.security.Key;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
/**
* DESEncryption實現了DES對稱加密
*
* @author PacoYang
*
*/
public class DESEncryption {
/**
* 創建祕鑰函數,並將祕鑰保存在文件key.txt中
*
*/
public static void setKey() throws Exception {
KeyGenerator kg = KeyGenerator.getInstance("DESede");// 設定加密類型爲三重DES加密，這裏可以改爲DES或AES加密，請大家看API文檔
kg.init(168);// 設定祕鑰長度爲112，三重DES的祕鑰長度可選112或168
SecretKey k = kg.generateKey();// 生成祕鑰
// 下面保存生成好的祕鑰
FileOutputStream f = new FileOutputStream("key.txt");
ObjectOutputStream ops = new ObjectOutputStream(f);
ops.writeObject(k);
}
/**
* 獲取祕鑰函數，根據URL路徑讀取文件中的祕鑰
* @param url 祕鑰路徑
* @return 返回祕鑰
*/
public static Key getKey(String url) throws Exception {
FileInputStream f = new FileInputStream(url);
ObjectInputStream ips = new ObjectInputStream(f);
Key k = (Key) ips.readObject();
return k;
}
/**
* 加密函數
* @param k 祕鑰
* @param code 要加密的代碼
* @return 返回加密後的內容
*/
public static String encrypt(Key k, String code) throws Exception {
Cipher cp = Cipher.getInstance("DESede");
cp.init(Cipher.ENCRYPT_MODE, k);
byte codebyte[] = code.getBytes("UTF8");
byte encode[] = cp.doFinal(codebyte);
return parseByte2HexStr(encode);
}
/**
* 解密函數
* @param k 祕鑰
* @param code 要解密的代碼
* @return 返回解密後的內容
*/
public static String decrypt(Key k, String code) throws Exception {
Cipher cp = Cipher.getInstance("DESede");
cp.init(Cipher.DECRYPT_MODE, k);
byte codebyte[] = parseHexStr2Byte(code);
byte decode[] = cp.doFinal(codebyte);
return new String(decode);
}
// main函數用於測試
public static void main(String[] args) throws Exception {
String s = "abc123abc321";
DESEncryption.setKey();
Key k = DESEncryption.getKey("key.txt");
String encode = DESEncryption.encrypt(k,s);
System.out.println(encode);
String decode = DESEncryption.decrypt(k,encode);
System.out.println(decode);
}
/**
* 將二進制轉換成16進值制 ，防止byte[]數字轉換成string類型時造成的數據損失
* @param buf
* @return 返回16進制轉換成的string
*/
public static String parseByte2HexStr(byte buf[]) {
StringBuffer sb = new StringBuffer();
for (int i = 0; i < buf.length; i++) {
String hex = Integer.toHexString(buf[i] & 0xFF);
if (hex.length() == 1) {
hex = '0' + hex;
}
sb.append(hex.toUpperCase());
}
return sb.toString();
}
/**
* 將16進制轉換爲二進制
* @param hexStr 16進制的數組轉換成String類型再傳過來的參數
* @return 轉換回來的二進制數組
*/
public static byte[] parseHexStr2Byte(String hexStr) {
if (hexStr.length() < 1)
return null;
byte[] result = new byte[hexStr.length() / 2];
for (int i = 0; i < hexStr.length() / 2; i++) {
int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2),
16);
result[i] = (byte) (high * 16 + low);
}
return result;
}
}