[原创]Java实现PKCS7填充的DES加密(修订版)

      在一个项目中，要求C#和Java交互，为了保障数据的安全传输，我们用到DES加密。
在DES加密中，要求指定Key，IV，CipherMode（CBC），PaddingMode。Key和IV，CipherMode都好说，只是PaddingMode不好指定，因为C#的模式有：ANSIX923、ISO10126、None、PKCS7、Zero，而Java有：OAEPWith<digest>And<mgf>Padding、PKCS5Padding、SSL3Padding，没有交集呀。
      我用C＃先写出来的，PaddingMode = PKCS7，Java方的不好作了。没有办法，只好帮人家写一个Java的例子，于是有了下面的代码：（Java高手不要笑话呀）

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

import sun.misc.BASE64Encoder;
  
    /**//*
    作者:阿牛(牛昆亮) QQ:273352165 MSN:niukl@hotmail.com
    
    声明:可以免费使用,请您保留此信息
        如果您有什么改过,记得告诉我!
    */

     public class DesPKCS7Encrypter { 
         Cipher ecipher; 
         Cipher dcipher;
         
         DesPKCS7Encrypter(byte[] keyBytes, byte[] ivBytes)
             throws Exception
         {
              Init(keyBytes,ivBytes);
         }
       
         
         DesPKCS7Encrypter(DESKeySpec keySpec, IvParameterSpec ivSpec)
            throws Exception             
         {
             Init(keySpec,ivSpec);
         }
          private void Init(byte[] keyBytes, byte[] ivBytes)
             throws Exception
         {
             DESKeySpec dks = new DESKeySpec(keyBytes);
             SecretKeyFactory keyFactory = SecretKeyFactory.getInstance( "DES" );
             SecretKey key = keyFactory.generateSecret( dks );
             IvParameterSpec iv = new IvParameterSpec(ivBytes);
             Init(key,iv);
             
         }
         
         private void Init(DESKeySpec keySpec, IvParameterSpec iv)
             throws Exception
         {
                SecretKeyFactory keyFactory = SecretKeyFactory.getInstance( "DES" );
             SecretKey key = keyFactory.generateSecret( keySpec );
             Init(key,iv);
        }
         
         private void Init(SecretKey key, IvParameterSpec iv)
             throws Exception
         {
             AlgorithmParameterSpec paramSpec = iv; 
             try { 
                 ecipher = Cipher.getInstance("DES/CBC/NoPadding"); 
                 dcipher = Cipher.getInstance("DES/CBC/NoPadding"); 
  
                 // CBC requires an initialization vector 
                 ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec); 
                 dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec); 
             }
             catch (Exception e) { 
                 throw e;
             }
            
         }
  
  
         public void encrypt(InputStream in, OutputStream out) { 
             try { 
                 // Bytes written to out will be encrypted 
                 out = new CipherOutputStream(out, ecipher); 
                 byte[] buf = new byte[this.ecipher.getBlockSize()];
  
                 // Read in the cleartext bytes and write to out to encrypt 
                 int numRead = 0;
                 while (true)
                 {
                     numRead = in.read(buf);
                     boolean bBreak = false;
                     if(numRead == -1 || numRead < buf.length)
                      {
                         int pos = numRead == -1? 0:numRead;
                         byte byteFill = (byte)(buf.length - pos);
                         for(int i = pos;i<buf.length; ++i)
                         {
                             buf[i] = byteFill;
                         }
                         bBreak = true;
                     }
                     out.write(buf);
                     
                     if(bBreak)
                         break;
                } 
                out.close(); 
             } catch (java.io.IOException e) { 
                 System.out.println("Exception e in encrypt="+e); 
             } 
         } 
  
         public void decrypt(InputStream in, OutputStream out) { 
             try { 
                 // Bytes read from in will be decrypted 
                 in = new CipherInputStream(in, dcipher); 
                 byte[] buf = new byte[this.dcipher.getBlockSize()];
                  
                 // Read in the decrypted bytes and write the cleartext to out 
                 int numRead = 0; 
                 while ((numRead = in.read(buf)) >= 0) { 
                     if(in.available() > 0)
                     {
                         out.write(buf, 0, numRead);                          
                     }
                     else
                     {
                         byte byteBlock = buf[buf.length -1];
                         int i = 0;
                         for(i = buf.length - byteBlock; i >= 0 && i < buf.length; ++i)
                         {
                             if(buf[i] != byteBlock)
                             {
                                 break;
                             }
                         }
                         
                         if(i == buf.length)
                         {
                            out.write(buf,0,buf.length - byteBlock); 
                         }
                         else
                         {
                             out.write(buf);
                         }
                     }
                 }
                 
                 out.close(); 
             } catch (java.io.IOException e) { 
                 System.out.println("Exception e in decrypt="+e); 
             } 
         } 
         
         public static void main(String args[]) 
         { 
             try 
             { 
                 // 生成Key和IV
                 byte[] byteKey = new byte[8]; //"12345678".getBytes("ASCII");
                 byte[] byteIv =  new byte[8]; //"98765432".getBytes("ASCII");
                 FileInputStream fisKey = new FileInputStream("key.dat");
                 FileInputStream fisIv = new FileInputStream("iv.dat");
                 fisKey.read(byteKey);
                 fisIv.read(byteIv);
                 fisKey.close();
                 fisIv.close();
                 
                 // 创建加密实例 
                 DesPKCS7Encrypter encrypter = new DesPKCS7Encrypter(byteKey,byteIv); 
                 // 生成要加密的数据 
                 String strData = "ni hao";
                 System.out.println(strData);
                 ByteArrayInputStream bais = new ByteArrayInputStream(strData.getBytes("utf-8"));
                 // 声明加密输出
                 ByteArrayOutputStream baos = new ByteArrayOutputStream();
                 // Base64 加密实例
                 BASE64Encoder base64Encoder = new BASE64Encoder();
                 
                 //加密
                 encrypter.encrypt(bais,baos); 
                 
                 //Base64加密
                 String outStr = base64Encoder.encode(baos.toByteArray());
                 //结果
                 System.out.println(outStr);
                 
                 // 初始化解密数据
                 bais = new ByteArrayInputStream(baos.toByteArray());
                 // 声明解密输出
                 baos = new ByteArrayOutputStream();
                 // 解密 
                 encrypter.decrypt(bais,baos); 
                 //查看解密结果
                 System.out.println(baos.toString("utf-8")); 
                 
           } catch (Exception e) { 
             System.out.println("Exception e="+e); 
           }
        } 
     } 

      也许还有更好的方法，也许Java已经有了该方法。还请高手告诉我呀。