Implementation method of des encryption and decryption in PHP and .net

sealed public class CryptoHelper
 {
     /// <summary>
     /// Encrypts the specified input.
     /// </summary>
     /// <param name="input">The input.</param>
     /// <param name="key">key</param>
     /// <param name="iv">iv</param>
     /// <returns></returns>
     public static string EncryptDes(string input, byte[] key, byte[] iv)
     {
         if (input == null || == 0)
             return ;

         DESCryptoServiceProvider des = new DESCryptoServiceProvider();
         MemoryStream ms = null;
         CryptoStream encStream = null;
         StreamWriter sw = null;
         string result = ;

         try
         {
             ms = new MemoryStream();

             // Create a CryptoStream using the memory stream and the
             // CSP DES key. 
             // = ;
             // = PaddingMode.PKCS7; 
             encStream = new CryptoStream(ms, (key, iv), );

             // Create a StreamWriter to write a string
             // to the stream.
             sw = new StreamWriter(encStream);

             // Write the plaintext to the stream.
             (input);

             ();
             ();
             ();

 
             result = Convert.ToBase64String((), 0, Convert.ToInt32(, ));
         }
         finally
         {
             //close objects
             if (sw != null)
                 ();
             if (encStream != null)
                 ();
             if (ms != null)
                 ();
         }

         // Return the encrypted string
         return result;
     }
     /// <summary>
     /// Decrypts the specified input.
     /// </summary>
     /// <param name="input">the input.</param>
     /// <param name="key">key</param>
     /// <param name="iv">iv</param>
     /// <returns></returns>
     public static string DecryptDes(string input, byte[] key, byte[] iv)
     {
         byte[] buffer;
         try { buffer = Convert.FromBase64String(input); }
         catch () { return ; }
         // length is zero, or not an even multiple of four (plus a few other cases)
         catch () { return ; }

         DESCryptoServiceProvider des = new DESCryptoServiceProvider();
         MemoryStream ms = null;
         CryptoStream encStream = null;
         StreamReader sr = null;
         string result = ;

         try
         {
             ms = new MemoryStream(buffer);

             // Create a CryptoStream using the memory stream and the
             // CSP DES key.
             encStream = new CryptoStream(ms, (key, iv), );

             // Create a StreamReader for reading the stream.
             sr = new StreamReader(encStream);

             // Read the stream as a string.
             result = ();
         }
         finally
         {
             //close objects
             if (sr != null)
                 ();
             if (encStream != null)
                 ();
             if (ms != null)
                 ();
         }

         return result;
     }
 }

 
//Call

 string key = "abcdefgh";
 string iv = "abcdefgh";
 string msg="test string";
 string rs1 = (msg, (key), (iv));
 string rs2 = (rs1, (key), (iv));