Security C#

#region (C) 1998-2009 AUTUMOON LAB.
/* *************************************************
* Solution:    Autumoon Code Library - Team Edition.
 * 
 * Project:     Common Foundation.
 * 
 * Description: The common tool class.
 * 
 * Author:      ZeroCool.
 * 
 * Created:     03/02/2008
 * 
 * (C) 1998-2009 Autumoon Lab.
 * ************************************************/
#endregion
#region ALL REFERENCE
using System;
using System.Security.Cryptography;
using System.IO;
using System.Text;
#endregion
namespace Autumoon.CodeLibrary.CommonFoundation
{
    public class Utilities
    {
        // Properties and fields.
        #region Properties and fields.
        private static byte[] _bytes = ASCIIEncoding.ASCII.GetBytes("ACLT2008");
        #endregion
        // Constructors.
        #region Constructors
        #endregion
        // Public methods.
        #region Public Methods
        /// 
        /// Encrypt a string.
        /// 

        /// The original string.
        /// The encrypted string.
        /// This exception will be thrown when the original string is null or empty.
        public static string Encrypt(string originalString)
        {
            if (String.IsNullOrEmpty(originalString))
            {
                throw new ArgumentNullException("The string which needs to be encrypted can not be null.");
            }
            DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
            MemoryStream memoryStream = new MemoryStream();
            CryptoStream cryptoStream = new CryptoStream(memoryStream, cryptoProvider.CreateEncryptor(_bytes, _bytes), CryptoStreamMode.Write);
            StreamWriter writer = new StreamWriter(cryptoStream);
            writer.Write(originalString);
            writer.Flush();
            cryptoStream.FlushFinalBlock();
            writer.Flush();
            return Convert.ToBase64String(memoryStream.GetBuffer(), 0, (int)memoryStream.Length);
        }
        /// 
        /// Decrypt a crypted string.
        /// 

        /// The crypted string.
        /// The decrypted string.
        /// This exception will be thrown when the crypted string is null or empty.
        public static string Decrypt(string cryptedString)
        {
            if (String.IsNullOrEmpty(cryptedString))
            {
                throw new ArgumentNullException("The string which needs to be decrypted can not be null.");
            }
            DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
            MemoryStream memoryStream = new MemoryStream(Convert.FromBase64String(cryptedString));
            CryptoStream cryptoStream = new CryptoStream(memoryStream, cryptoProvider.CreateDecryptor(_bytes, _bytes), CryptoStreamMode.Read);
            StreamReader reader = new StreamReader(cryptoStream);
            return reader.ReadToEnd();
        }
        /// 
        /// Handle SQL sensitive charactors in original text.
        /// 

        /// The orginal code content.
        /// The SQL storable text.
        public static string HandleSQLSensitiveChars(string originalText)
        {
            if (String.IsNullOrEmpty(originalText))
            {
                return String.Empty;
            }
            return originalText.Replace("<", "<").Replace(">", ">").Replace("\"", """).Replace(" ", " ").Replace("©", "©").Replace("®", "®").Replace("&", "&").Replace("\'", "'");
        }
        /// 
        /// Handle the SQL stored text for resuming SQL sensitive charactors.
        /// 

        /// The SQL stored text.
        /// The orginal code text.
        public static string ResumeSQLStoredText(string storableText)
        {
            if (String.IsNullOrEmpty(storableText))
            {
                return String.Empty;
            }
            return storableText.Replace("<", "<").Replace(">", ">").Replace(""", "\"").Replace(" ", " ").Replace("©", "©").Replace("®", "®").Replace("&", "&").Replace("'", "\'");
        }
        #endregion
    }
}