package data;

import java.security.*;
import javax.crypto.*;
import javax.crypto.spec.*;
import java.io.*;

/**
* Security 提供了一个安全算法类,其中包括对称密码算法和散列算法
*/
public final class Security
{
/**
  * 对称加密方法
  * @param byteSource 需要加密的数据
  * @return 经过加密的数据
  * @throws Exception
  */
public static byte[] symmetricEncrypto(byte[] byteSource) throws Exception
{
  ByteArrayOutputStream baos = new ByteArrayOutputStream();
  try
  {
   int mode = Cipher.ENCRYPT_MODE;
   SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
   byte[] keyData = {1, 9, 8, 2, 0, 8, 2, 1};
   DESKeySpec keySpec = new DESKeySpec(keyData);
   Key key = keyFactory.generateSecret(keySpec);
   Cipher cipher = Cipher.getInstance("DES");
   cipher.init(mode, key);
   int blockSize = cipher.getBlockSize();
   int position = 0;
   int length = byteSource.length;
   boolean more = true;
   while(more)
   {
    if(position + blockSize <= length)
    {
     baos.write(cipher.update(byteSource, position, blockSize));
     position += blockSize;
    }
    else
    {
     more = false;
    }
   }
   if(position < length)
   {
    baos.write(cipher.doFinal(byteSource, position, length - position));
   }
   else
   {
    baos.write(cipher.doFinal());
   }
   return baos.toByteArray();
  }
  catch(Exception e)
  {
   throw e;
  }
  finally
  {
   baos.close();
  }
}
/**
  * 对称解密方法
  * @param byteSource 需要解密的数据
  * @return 经过解密的数据
  * @throws Exception
  */
public static byte[] symmetricDecrypto(byte[] byteSource) throws Exception
{
  ByteArrayOutputStream baos = new ByteArrayOutputStream();
  try
  {
   int mode = Cipher.DECRYPT_MODE;
   SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
   byte[] keyData = {1, 9, 8, 2, 0, 8, 2, 1};
   DESKeySpec keySpec = new DESKeySpec(keyData);
   Key key = keyFactory.generateSecret(keySpec);
   Cipher cipher = Cipher.getInstance("DES");
   cipher.init(mode, key);
   int blockSize = cipher.getBlockSize();
   int position = 0;
   int length = byteSource.length;
   boolean more = true;
   while(more)
   {
    if(position + blockSize <= length)
    {
     baos.write(cipher.update(byteSource, position, blockSize));
     position += blockSize;
    }
    else
    {
     more = false;
    }
   }
   if(position < length)
   {
    baos.write(cipher.doFinal(byteSource, position, length - position));
   }
   else
   {
    baos.write(cipher.doFinal());
   }
   return baos.toByteArray();
  }
  catch(Exception e)
  {
   throw e;
  }
  finally
  {
   baos.close();
  }
}
/**
  * 散列算法
  * @param byteSource 需要散列计算的数据
  * @return 经过散列计算的数据
  * @throws Exception
  */
public static byte[] hashMethod(byte[] byteSource) throws Exception
{
  try
  {
   MessageDigest currentAlgorithm = MessageDigest.getInstance("SHA-1");
   currentAlgorithm.reset();
   currentAlgorithm.update(byteSource);
   return currentAlgorithm.digest();
  }
  catch(Exception e)
  {
   throw e;
  }
}
}