一个可以用来加密/解密的类（原创）

可以用来加/解密数据库用户、密码等

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

namespace Common
{
 /// <summary>
 /// SecurityService 的摘要说明。
 /// </summary>
 public class SecurityService
 {
   static protected Byte[] byteKey  = {125, 14, 45, 67, 112, 79, 77, 99, 37, 104, 13, 9, 118, 51, 87, 108};
   static protected Byte[] byteIV  = {86, 19, 79, 15, 72, 58, 117, 45};
   static public string SymmetricEncrypt(String sPlainText)
   {
   Byte[] bytePlaintext;
   MemoryStream EncryptedStream;
   ICryptoTransform Encryptor;
      CryptoStream TheCryptoStream;
      if(sPlainText=="")  return "";
   bytePlaintext = Encoding.ASCII.GetBytes(sPlainText);
   EncryptedStream = new MemoryStream(sPlainText.Length);
   Encryptor = GetEncryptor();
   TheCryptoStream = new CryptoStream(EncryptedStream, Encryptor, CryptoStreamMode.Write);
   TheCryptoStream.Write(bytePlaintext, 0, bytePlaintext.Length);
   TheCryptoStream.FlushFinalBlock();
   TheCryptoStream.Close();

   return Convert.ToBase64String(EncryptedStream.ToArray());

  }//End Function

  static public string SymmetricDecrypt(String sEncryptedText)
  {
   Byte[] byteEncrypted;
   MemoryStream PlaintextStream;
   ICryptoTransform Decryptor;
   CryptoStream TheCryptoStream;

   if (sEncryptedText == "")  return "";

   byteEncrypted = Convert.FromBase64String(sEncryptedText.Trim());
   PlaintextStream = new MemoryStream(sEncryptedText.Length);
   Decryptor = GetDecryptor();
   TheCryptoStream = new CryptoStream(PlaintextStream, Decryptor, CryptoStreamMode.Write);

   TheCryptoStream.Write(byteEncrypted, 0, byteEncrypted.Length);
   TheCryptoStream.FlushFinalBlock();
   TheCryptoStream.Close();

   return Encoding.ASCII.GetString(PlaintextStream.ToArray());

  }//End Function

  static private ICryptoTransform GetEncryptor()
  {
     RC2CryptoServiceProvider CryptoProvider = new RC2CryptoServiceProvider();
              CryptoProvider.Mode = CipherMode.CBC;
     return CryptoProvider.CreateEncryptor(byteKey, byteIV);

   }//End Function

  static private ICryptoTransform  GetDecryptor()
  {
   RC2CryptoServiceProvider CryptoProvider = new RC2CryptoServiceProvider();
    CryptoProvider.Mode = CipherMode.CBC;
             return CryptoProvider.CreateDecryptor(byteKey, byteIV);

   }//End Function
 }
}

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