C # Base64 plus decryption

usingSystem;usingSystem.Collections.Generic;usingSystem.Text;usingSystem.Security.Cryptography;usingSystem.IO;namespaceencryptanddecrypt{ Public classCryptoutil {//random definition of 8-byte key and initialization vector        Private byte[] key_64 =New byte[] {1,2,3,3,4,5,6,4}; Private byte[] iv_64 =New byte[] {2,3,4,5,3,4,3,2}; /// <summary>        ///Encrypt/// </summary>        /// <param name= "str" >strings that need to be encrypted</param>        /// <returns>the encrypted string</returns>         Public stringEncrypt (stringstr) {            if(str = ="")returnstr; DESCryptoServiceProvider CryptoProvider=NewDESCryptoServiceProvider (); MemoryStream Ms=NewMemoryStream (); CryptoStream CS=NewCryptoStream (MS, Cryptoprovider.createencryptor (key_64, iv_64), cryptostreammode.write); StreamWriter SW=NewStreamWriter (CS); stringCyrstr =""; Try{SW.                Write (str); Sw.                Flush (); Cs.                FlushFinalBlock (); Ms.                Flush (); //Converts an encrypted byte array into a stringCyrstr = convert.tobase64string (ms. GetBuffer (),0, (int) Ms.            Length); }            finally{SW.                Close (); Cs.                Close (); Ms.                Close ();            Cryptoprovider.clear (); }            returnCyrstr; }        /// <summary>        ///decryption/// </summary>        /// <param name= "str" >A string that has been encrypted</param>        /// <returns>the decrypted string</returns>         Public stringDecrypt (stringstr) {            if(str = ="")returnstr; //Convert a string into a byte array            byte[] Strbyte =convert.frombase64string (str); DESCryptoServiceProvider CryptoProvider=NewDESCryptoServiceProvider (); MemoryStream Ms=NewMemoryStream (Strbyte); CryptoStream CS=NewCryptoStream (MS, Cryptoprovider.createdecryptor (key_64, iv_64), cryptostreammode.read); StreamReader SR=NewStreamReader (CS); stringUncrystr =""; Try{uncrystr=Sr.            ReadToEnd (); }            finally{Sr.                Close (); Cs.                Close (); Ms.                Close ();            Cryptoprovider.clear (); }            returnUncrystr; }    }     Public classProgram { Public Static voidMain (string[] args) {Cryptoutil crypt=NewCryptoutil (); stringText ="KingSoft"; stringEn =Crypt.            Encrypt (text);            Console.WriteLine (en); stringDe =Crypt.            Decrypt (en);        Console.WriteLine (DE); }    }}

C # Base64 plus decryption