對稱式加密解密類c#

namespace EncryptDLL
{
    #region 對稱式加密類
    /// <summary>
    /// 對稱式加密解密類
    /// </summary>
    public static class SymmetricEncryptClass
    {
        #region 對稱式加密代碼
        /// <summary>
        /// 對稱式加密方法
        /// </summary>
        /// <param name="strMsg">要加密的資料</param>
        /// <param name="key">加密Key</param>
        /// <param name="IV">加密向量</param>
        /// <returns>返回加密後的資料，類型byte[]</returns>
        public static byte[] SymmetricEncrptFunction(this string strMsg, string key, string IV)
        {
            TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
            SHA1 sha1 = new SHA1CryptoServiceProvider();
            //初始密鑰的設定
            string strNamePlusBirthday = key + IV;
            string strKey = new string(strNamePlusBirthday.Reverse().ToArray());
            if (sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).Length > tdes.Key.Length)
            {
                tdes.Key = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).ToString().Substring(0, tdes.Key.Length));
            }
            else if (sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).Length < tdes.Key.Length)
            {
                tdes.Key = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).ToString().PadRight(tdes.Key.Length, ' '));
            }
            //初始向量的設定

            if (sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).Length > tdes.IV.Length)
            {
                tdes.IV = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).ToString().Substring(0, tdes.IV.Length));
            }
            else if (sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).Length < tdes.IV.Length)
            {
                tdes.IV = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).ToString().PadRight(tdes.IV.Length, ' '));
            }
            byte[] encryptBuffer = Encoding.Default.GetBytes(strMsg);
            MemoryStream streamMemory = new MemoryStream();
            CryptoStream cryStream = null;//加密流
            byte[] readBuffer;//用來接受加密資料
            try
            {
                cryStream = new CryptoStream(streamMemory, new TripleDESCryptoServiceProvider().CreateEncryptor(tdes.Key, tdes.IV), CryptoStreamMode.Write);
                cryStream.Write(encryptBuffer, 0, encryptBuffer.Length);
                cryStream.FlushFinalBlock();
            }
            catch
            {
                return null;
            }
            finally
            {
                readBuffer = streamMemory.ToArray();
                cryStream.Close();
                streamMemory.Close();
            }
            return readBuffer;
        }

        #endregion
        #region 對稱解密代碼
        /// <summary>
        /// 對稱解密方法
        /// </summary>
        /// <param name="bufMsg">需要解密的資料</param>
        /// <param name="key">解密Key</param>
        /// <param name="IV">解密向量</param>
        /// <returns>解密後的資料</returns>
        public static string SymmetricDecryptionFunction(this byte[] bufMsg, string key, string IV)
        {
            TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
            SHA1 sha1 = new SHA1CryptoServiceProvider();
            //初始密鑰的設定
            string strNamePlusBirthday = key + IV;
            string strKey = new string(strNamePlusBirthday.Reverse().ToArray());
            if (sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).Length > tdes.Key.Length)
            {
                tdes.Key = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).ToString().Substring(0, tdes.Key.Length));
            }
            else if (sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).Length < tdes.Key.Length)
            {
                tdes.Key = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strKey)).ToString().PadRight(tdes.Key.Length, ' '));
            }
            //初始向量的設定
            if (sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).Length > tdes.IV.Length)
            {
                tdes.IV = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).ToString().Substring(0, tdes.IV.Length));
            }
            else if (sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).Length < tdes.IV.Length)
            {
                tdes.IV = Encoding.Default.GetBytes(sha1.ComputeHash(Encoding.Default.GetBytes(strNamePlusBirthday)).ToString().PadRight(tdes.IV.Length, ' '));
            }
            byte[] readBuffer = bufMsg;
            MemoryStream streamRead = new MemoryStream(readBuffer);
            CryptoStream deCryStream = null;
            byte[] bufferReader;
            try
            {
                deCryStream = new CryptoStream(streamRead, new TripleDESCryptoServiceProvider().CreateDecryptor(tdes.Key, tdes.IV), CryptoStreamMode.Read);
                bufferReader = new byte[readBuffer.Length];
                deCryStream.Read(bufferReader, 0, bufferReader.Length);
            }
            finally
            {
                deCryStream.Close();
                streamRead.Close();
            }
            string deCryString = Encoding.Default.GetString(bufferReader);
            return deCryString;
        }
        #endregion
    }
    #endregion
}