C#做的一個加密/解密的類

大家要有興趣，可以一起來討論一下 WebService資料互動安全問題，以下的這個代碼，可以用於Dotnet環境下的任何託管方式的應用程式，在實際應用中有兩個執行個體。其中，有一個掛在Internet上的，URL:http://www.tttsss.com/webservice/THRDataService.asmx , 有興趣的可以看看其中的Soap資訊。當然，要看裡面的加密解密過程，就沒辦法了！否則，我呀太沒面子了，是吧！

          前兩年寫的東西，現在整理一下發出來！以前公司需要做WebService，並且對WebService的SoapHeader進行加密，所以就寫了這麼個東東！使用這個類，需要密鑰管理！為了保證資料的安全性往往要對資料進行加密，但是加密的缺點之一，就是影響程式的運行效率，所以，當時我的思路是只對使用者的登入資訊（使用者名稱，密碼）進行加密！資料用明文傳輸，使用者資訊驗證沒有通過的情況下, 不進行資料轉送。

          實際在網路通訊中，使用密鑰匙的方式並非無懈可擊，如果駭客可以捕捉到用祕密金鑰加密的，使用者驗證資訊，然後，做個類比請求，向提供WebService的伺服器發請求，還是可以獲得請求資料！所以，我又使用了IP或者網域名稱綁定的方式！畢竟，WebService不是直接對終端使用者提供的！所以，加上以上這些手段後，就算有不良企圖者想通過非法方式獲得WebService提供的服務，就再費點勁吧！            

          還有一點安全建議，就是週期性更換密鑰，在這個例子中，我用的是對稱式加密，加密方和解密方的密鑰一致！週期性更換密鑰可以讓安全性提高一大截！

          大家要有更好的方法，或者建議，可以留言討論一下！共同提高！

代碼如下：

using System;
using System.Security.Cryptography ;
using System.Text;
using System.IO;

namespace SEDO
{ 
 /// <summary>
 /// SEDO 的摘要說明。
 /// SEDO 實現的是用一個封裝了4種對稱式加密方法(Des,Rc2,Rijndael,TripleDes)的組件
 ///
 /// 注意事項：
 /// 1:TripleDes和Rijndael加密/解密對象使用16或者24位byte的Key
 /// 2:Rijndael只能使用16位的初始化向量IV
 /// 3:Des和Rc2均使用8位Byte的Key和IV
 /// 4:對需要加密/解密的資料流採用何種方法進行編碼/解碼，由調用組件的使用者自己決定
 /// 5:密鑰和初始化向量IV由使用者自己定義
 /// 程式員： 王海波 2003-05-19 hwnanghb@21cn.com
 /// </summary>
 
 //定義加密類型的枚舉
 public enum EncryptionAlgorithm {Des = 1, Rc2, Rijndael, TripleDes};

 //定義加密類
 internal class EncryptTransformer
 {
  private EncryptionAlgorithm algorithmID;
  private byte[] initVec;
  private byte[] encKey;

  internal EncryptTransformer(EncryptionAlgorithm algId)
  {
   //Save the algorithm being used.
   algorithmID = algId;
  }

  internal ICryptoTransform GetCryptoServiceProvider(byte[] bytesKey)
  {
   //當資料密鑰Key或者初始化向量IV為空白的時候，將使用加密對象自動產生的密鑰Key或者初始化向量IV
   switch (algorithmID)
   {
    case EncryptionAlgorithm.Des:
    {
     DES des = new DESCryptoServiceProvider();
     des.Mode = CipherMode.CBC;

     // See if a key was provided
     if (null == bytesKey)
     {
      encKey = des.Key;
     }
     else
     {
      des.Key = bytesKey;
      encKey = des.Key;
     }
     // See if the client provided an initialization vector
     if (null == initVec)
     { // Have the algorithm create one
      initVec = des.IV;
     }
     else
     { //No, give it to the algorithm
      des.IV = initVec;
     }
     return des.CreateEncryptor();
    }
    case EncryptionAlgorithm.TripleDes:
    {
     TripleDES des3 = new TripleDESCryptoServiceProvider();
     des3.Mode = CipherMode.CBC;
     // See if a key was provided
     if (null == bytesKey)
     {
      encKey = des3.Key;
     }
     else
     {
      des3.Key = bytesKey;
      encKey = des3.Key;
     }
     // See if the client provided an IV
     if (null == initVec)
     { //Yes, have the alg create one
      initVec = des3.IV;
     }
     else
     { //No, give it to the alg.
      des3.IV = initVec;
     }
     return des3.CreateEncryptor();
    }
    case EncryptionAlgorithm.Rc2:
    {
     RC2 rc2 = new RC2CryptoServiceProvider();
     rc2.Mode = CipherMode.CBC;
     // Test to see if a key was provided
     if (null == bytesKey)
     {
      encKey = rc2.Key;
     }
     else
     {
      rc2.Key = bytesKey;
      encKey = rc2.Key;
     }
     // See if the client provided an IV
     if (null == initVec)
     { //Yes, have the alg create one
      initVec = rc2.IV;
     }
     else
     { //No, give it to the alg.
      rc2.IV = initVec;
     }
     return rc2.CreateEncryptor();
    }
    case EncryptionAlgorithm.Rijndael:
    {
     Rijndael rijndael = new RijndaelManaged();
     rijndael.Mode = CipherMode.CBC;
     // Test to see if a key was provided
     if(null == bytesKey)
     {
      encKey = rijndael.Key;
     }
     else
     {
      rijndael.Key = bytesKey;
      encKey = rijndael.Key;
     }
     // See if the client provided an IV
     if(null == initVec)
     { //Yes, have the alg create one
      initVec = rijndael.IV;
     }
     else
     { //No, give it to the alg.
      rijndael.IV = initVec;
     }
     return rijndael.CreateEncryptor();
    }
    default:
    {
     throw new CryptographicException("Algorithm ID '" +
      algorithmID +
      "' not supported.");
    }
   }
  }

  //加密的位移向量
  internal byte[] IV
  {
   get{return initVec;}
   set{initVec = value;}
  }
  //加密的密鑰
  internal byte[] Key
  {
   get{return encKey;}
   set{encKey = value;}
  }

 }

 //定義解密類
 internal class DecryptTransformer
 {
  private EncryptionAlgorithm algorithmID;
  private byte[] initVec;
  private byte[] encKey;

  internal DecryptTransformer(EncryptionAlgorithm deCryptId)
  {
   algorithmID = deCryptId;
  }

  //加密的位移向量
  internal byte[] IV
  {
   get{return initVec;}
   set{initVec = value;}
  }
  
  //加密的密鑰
  internal byte[] Key
  {
   get{return encKey;}
   set{encKey = value;}
  }

  internal ICryptoTransform GetCryptoServiceProvider(byte[] bytesKey)
  {
   //當資料密鑰Key或者初始化向量IV為空白的時候，將使用加密對象自動產生的密鑰Key或者初始化向量IV
   switch (algorithmID)
   {
    case EncryptionAlgorithm.Des:
    {
     DES des = new DESCryptoServiceProvider();
     des.Mode = CipherMode.CBC;
     des.Key = bytesKey;
     des.IV = initVec;
     return des.CreateDecryptor();
    }
    case EncryptionAlgorithm.TripleDes:
    {
     TripleDES des3 = new TripleDESCryptoServiceProvider();
     des3.Mode = CipherMode.CBC;
     return des3.CreateDecryptor(bytesKey, initVec);
    }
    case EncryptionAlgorithm.Rc2:
    {
     RC2 rc2 = new RC2CryptoServiceProvider();
     rc2.Mode = CipherMode.CBC;
     return rc2.CreateDecryptor(bytesKey, initVec);
    }
    case EncryptionAlgorithm.Rijndael:
    {
     Rijndael rijndael = new RijndaelManaged();
     rijndael.Mode = CipherMode.CBC;
     return rijndael.CreateDecryptor(bytesKey, initVec);
    }
    default:
    {
     throw new CryptographicException("Algorithm ID '" +
      algorithmID +
      "' not supported.");
    }
   }
  } //end GetCryptoServiceProvider
 
 }

 //定義加密者類
 public class Encryptor
 {
  private EncryptTransformer transformer;
  private byte[] initVec;
  private byte[] encKey;
 
  public Encryptor(EncryptionAlgorithm algId)
  {
   transformer = new EncryptTransformer(algId);
  }

  public byte[] Encrypt(byte[] bytesData, byte[] bytesKey,byte[] bytesIV)
  {
   //設定流對象用來儲存加密資料位元組流.
   MemoryStream memStreamEncryptedData = new MemoryStream();
   
   transformer.IV=bytesIV;
   transformer.Key=bytesKey;
 
   ICryptoTransform transform = transformer.GetCryptoServiceProvider(bytesKey);
   CryptoStream encStream = new CryptoStream(memStreamEncryptedData,transform,CryptoStreamMode.Write);

   try
   {
    //將加密資料寫進流對象
    encStream.Write(bytesData, 0, bytesData.Length);
   }
   catch(Exception ex)
   {
    throw new Exception("在資料加密的時候出現錯誤！錯誤提示： \n"  + ex.Message);
   }
   
   //設定加密的Key和初始向量IV屬性
   encKey = transformer.Key;
   initVec = transformer.IV;

   encStream.FlushFinalBlock();
   encStream.Close();

   //Send the data back.
   return memStreamEncryptedData.ToArray();
  }

  public byte[] IV
  {
   get{return initVec;}
   set{initVec = value;}
  }

  public byte[] Key
  {
   get{return encKey;}
   set{encKey = value;}
  }
 
 }

 //定義解密者類
 public class Decryptor
 {
  private DecryptTransformer transformer;
  private byte[] initVec;
  private byte[] encKey;

  public Decryptor(EncryptionAlgorithm algId)
  {
   transformer = new DecryptTransformer(algId);
  }

  public byte[] Decrypt(byte[] bytesData, byte[] bytesKey,byte[] bytesIV)
  {
   //設定流對象用來儲存解密資料位元組流.
   MemoryStream memStreamDecryptedData = new MemoryStream();

   //Pass in the initialization vector.
   transformer.IV = bytesIV;
   transformer.Key = bytesKey;

   ICryptoTransform transform = transformer.GetCryptoServiceProvider(bytesKey);
   CryptoStream decStream = new CryptoStream(memStreamDecryptedData,transform, CryptoStreamMode.Write);
   
   try
   {
    decStream.Write(bytesData, 0, bytesData.Length);
   }
   catch(Exception ex)
   {
    throw new Exception("在資料解密的時候出現錯誤！錯誤提示： \n" + ex.Message);
   }
   decStream.FlushFinalBlock();
   decStream.Close();
   // 返回解密資料.
   return memStreamDecryptedData.ToArray();
  }

  public byte[] IV
  {
   get{return initVec;}
   set{initVec = value;}
  }

  public byte[] Key
  {
   get{return encKey;}
   set{encKey = value;}
  }
 
 }

 //類描述：檔案加密/解密類
 public class SecurityFile
 {
  private DecryptTransformer Dec_Transformer;    //解密轉換器
  private EncryptTransformer Enc_Transformer;    //加密轉換器
  private byte[] initVec;
  private byte[] encKey;

  public SecurityFile(EncryptionAlgorithm algId)
  {
   Dec_Transformer = new DecryptTransformer(algId);
   Enc_Transformer = new EncryptTransformer(algId);
  }

  //加密的位移向量
  internal byte[] IV
  {
   get{return initVec;}
   set{initVec = value;}
  }
  //加密的密鑰
  internal byte[] Key
  {
   get{return encKey;}
   set{encKey = value;}
  }

  //功能描述：加密檔案
  public void EncryptFile(string inFileName, string outFileName, byte[] bytesKey, byte[] bytesIV)
  {
   try
   {
    FileStream fin = new FileStream(inFileName, FileMode.Open, FileAccess.Read);
    FileStream fout = new FileStream(outFileName, FileMode.OpenOrCreate, FileAccess.Write);
    fout.SetLength(0);
      
    //Create variables to help with read and write.
    byte[] bin = new byte[100]; //This is intermediate storage for the encryption.
    long rdlen = 0;              //This is the total number of bytes written.
    long totlen = fin.Length;    //This is the total length of the input file.
    int len;                     //This is the number of bytes to be written at a time.
 
    Enc_Transformer.IV=bytesIV;
    Enc_Transformer.Key=bytesKey;

    ICryptoTransform transform = Enc_Transformer.GetCryptoServiceProvider(bytesKey);         
    CryptoStream encStream = new CryptoStream(fout, transform, CryptoStreamMode.Write);
                             
    //Read from the input file, then encrypt and write to the output file.
    while(rdlen < totlen)
    {
     len = fin.Read(bin, 0, 100);
     encStream.Write(bin, 0, len);
     rdlen = rdlen + len;     
    }
 
    encStream.Close(); 
    fout.Close();
    fin.Close();    
   }
   catch(Exception ex)
   {
    throw new Exception("在檔案加密的時候出現錯誤！錯誤提示： \n" + ex.Message);
   }
  }

  //功能描述：解密檔案
  public void DecryptFile(string inFileName, string outFileName, byte[] bytesKey, byte[] bytesIV)
  {
   try
   {
    FileStream fin = new FileStream(inFileName, FileMode.Open, FileAccess.Read);
    FileStream fout = new FileStream(outFileName, FileMode.OpenOrCreate, FileAccess.Write);
    fout.SetLength(0);
      
    //Create variables to help with read and write.
    byte[] bin = new byte[100]; //This is intermediate storage for the encryption.
    long rdlen = 0;              //This is the total number of bytes written.
    long totlen = fin.Length;    //This is the total length of the input file.
    int len;                     //This is the number of bytes to be written at a time.
 
    Dec_Transformer.IV=bytesIV;
    Dec_Transformer.Key=bytesKey;

    ICryptoTransform transform = Dec_Transformer.GetCryptoServiceProvider(bytesKey);         
    CryptoStream encStream = new CryptoStream(fout, transform, CryptoStreamMode.Write);
                             
    //Read from the input file, then encrypt and write to the output file.
    while(rdlen < totlen)
    {
     len = fin.Read(bin, 0, 100);
     encStream.Write(bin, 0, len);
     rdlen = rdlen + len;     
    }
 
    encStream.Close(); 
    fout.Close();
    fin.Close();    
   }
   catch(Exception ex)
   {
    throw new Exception("在檔案加密的時候出現錯誤！錯誤提示： \n" + ex.Message);
   }
  }
 
 }

}