Encrypt a string : Encrypt Decrypt « Security « C# / C Sharp

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2. Security
3. Encrypt Decrypt

Encrypt a string

    
#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
        /// <summary>
        /// Encrypt a string.
        /// </summary>
        /// <param name="originalString">The original string.</param>
        /// <returns>The encrypted string.</returns>
        /// <exception cref="ArgumentNullException">This exception will be thrown when the original string is null or empty.</exception>
        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);
        }

        /// <summary>
        /// Decrypt a crypted string.
        /// </summary>
        /// <param name="cryptedString">The crypted string.</param>
        /// <returns>The decrypted string.</returns>
        /// <exception cref="ArgumentNullException">This exception will be thrown when the crypted string is null or empty.</exception>
        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();
        }

        /// <summary>
        /// Handle SQL sensitive charactors in original text.
        /// </summary>
        /// <param name="originalText">The orginal code content.</param>
        /// <returns>The SQL storable text.</returns>
        public static string HandleSQLSensitiveChars(string originalText)
        {
            if (String.IsNullOrEmpty(originalText))
            {
                return String.Empty;
            }

            return originalText.Replace("<", "&lt;").Replace(">", "&gt;").Replace("\"", "&quot;").Replace(" ", "&nbsp;").Replace("", "&copy;").Replace("", "&reg;").Replace("&", "&amp;").Replace("\'", "&apos;");
        }

        /// <summary>
        /// Handle the SQL stored text for resuming SQL sensitive charactors.
        /// </summary>
        /// <param name="storableText">The SQL stored text.</param>
        /// <returns>The orginal code text.</returns>
        public static string ResumeSQLStoredText(string storableText)
        {
            if (String.IsNullOrEmpty(storableText))
            {
                return String.Empty;
            }

            return storableText.Replace("&lt;", "<").Replace("&gt;", ">").Replace("&quot;", "\"").Replace("&nbsp;", " ").Replace("&copy;", "").Replace("&reg;", "").Replace("&amp;", "&").Replace("&apos;", "\'");
        }
        #endregion
    }
}

   
    
    
    
  

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