Encryption/Decryption with .NET

using System;
using System.Security.Cryptography;
using System.IO;
using System.Text;

namespace FangHome_Crypto
{
   /// <summary>
   /// SymmCrypto is a wrapper of System.Security.Cryptography.SymmetricAlgorithm classes
   /// and simplifies the interface. It supports customized SymmetricAlgorithm as well.
   /// </summary>
   public class SymmCrypto
   {
      /// <remarks>
      /// Supported .Net intrinsic SymmetricAlgorithm classes.
      /// </remarks>
      public enum SymmProvEnum : int
      {
         DES, RC2, Rijndael, TripleDES
      }

      private SymmetricAlgorithm mobjCryptoService;

      /// <remarks>
      /// Constructor for using an intrinsic .Net SymmetricAlgorithm class.
      /// </remarks>
      public SymmCrypto(SymmProvEnum NetSelected)
      {
         switch (NetSelected)
         {
            case SymmProvEnum.DES:
               mobjCryptoService = new DESCryptoServiceProvider();
               break;
            case SymmProvEnum.RC2:
               mobjCryptoService = new RC2CryptoServiceProvider();
               break;
            case SymmProvEnum.Rijndael:
               mobjCryptoService = new RijndaelManaged();
               break;
            case SymmProvEnum.TripleDES:
               mobjCryptoService = new TripleDESCryptoServiceProvider();
               break;
         }
      }

      /// <remarks>
      /// Constructor for using a customized SymmetricAlgorithm class.
      /// </remarks>
      public SymmCrypto(SymmetricAlgorithm ServiceProvider)
      {
         mobjCryptoService = ServiceProvider;
      }

      private byte[] GetLegalKey(string Key)
      {
         string sTemp = Key;
         mobjCryptoService.GenerateKey();
         byte[] bytTemp = mobjCryptoService.Key;
         int KeyLength = bytTemp.Length;
         if (sTemp.Length > KeyLength)
            sTemp = sTemp.Substring(0, KeyLength);
         else if (sTemp.Length < KeyLength)
            sTemp = sTemp.PadRight(KeyLength, ' ');

         return ASCIIEncoding.ASCII.GetBytes(sTemp);
      }

      private byte[] GetLegalIV()
      {
         // The initial string of IV may be modified with any data you like
         string sTemp = "救臆妲饣";
         mobjCryptoService.GenerateIV();
         byte[] bytTemp = mobjCryptoService.IV;
         int IVLength = bytTemp.Length;
         if (sTemp.Length > IVLength)
            sTemp = sTemp.Substring(0, IVLength);
         else if (sTemp.Length < IVLength)
            sTemp = sTemp.PadRight(IVLength, ' ');

         return ASCIIEncoding.ASCII.GetBytes(sTemp);
      }

      public string Encrypting(string Source, string Key)
      {
         // use UTF8 unicode conversion for two byte characters
         byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source);

         // create a MemoryStream so that the process can be done without I/O files
         System.IO.MemoryStream ms = new System.IO.MemoryStream();

         // set the private key
         mobjCryptoService.Key = GetLegalKey(Key);
         mobjCryptoService.IV = GetLegalIV();

         // create an Encryptor from the Provider Service instance
         ICryptoTransform encrypto = mobjCryptoService.CreateEncryptor();

         // create Crypto Stream that transforms a stream using the encryption
         CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);

         // write out encrypted content into MemoryStream
         cs.Write(bytIn, 0, bytIn.Length);
         cs.FlushFinalBlock();

         ms.Close();
         byte[] bytOut = ms.ToArray();

         // convert into Base64 so that the result can be used in xml
         return System.Convert.ToBase64String(bytOut);
      }

      public string Decrypting(string Source, string Key)
      {
         // convert from Base64 to binary
         byte[] bytIn = System.Convert.FromBase64String(Source);
         // create a MemoryStream with the input
         System.IO.MemoryStream ms = new System.IO.MemoryStream(bytIn, 0, bytIn.Length);

         // set the private key
         mobjCryptoService.Key = GetLegalKey(Key);
         mobjCryptoService.IV = GetLegalIV();

         // create a Decryptor from the Provider Service instance
         ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor();

         // create Crypto Stream that transforms a stream using the decryption
         CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);

         // read out the result from the Crypto Stream
         System.IO.StreamReader sr = new System.IO.StreamReader( cs );
         return sr.ReadToEnd();
      }
   }
} 

public SymmCrypto(SymmProvEnum NetSelected)<br />
{<br />
    switch (NetSelected)<br />
    {<br />
        case SymmProvEnum.DES:<br />
            mobjCryptoService = new DESCryptoServiceProvider();<br />
            break;<br />
        case SymmProvEnum.RC2:<br />
            mobjCryptoService = new RC2CryptoServiceProvider();<br />
            break;<br />
        case SymmProvEnum.Rijndael:<br />
            mobjCryptoService = new RijndaelManaged();<br />
            break;<br />
    }<br />
}

<br />
        public SymmCrypto(string algo)<br />
        {<br />
            mobjCryptoService = (SymmetricAlgorithm)CryptoConfig.CreateFromName( algo );<br />
        }

<br />
Imports System<br />
Imports System.Security.Cryptography<br />
Imports System.IO<br />
Imports System.Text<br />
<br />
'SymmCrypto is a wrapper of System.Security.Cryptography.SymmetricAlgorithm classes<br />
'and simplifies the interface. It supports customized SymmetricAlgorithm as well.<br />
'taken from http://www.codeproject.com/dotnet/encryption_decryption.asp#xx222556xx<br />
<br />
Public Class Encryptor<br />
    'Supported .Net intrinsic SymmetricAlgorithm classes.<br />
    Public Enum Providers<br />
        [DES]<br />
        [RC2]<br />
        [Rijndael]<br />
    End Enum<br />
<br />
    Private _CryptoService As SymmetricAlgorithm<br />
<br />
    'Constructor for using an intrinsic .Net SymmetricAlgorithm class.<br />
    Public Sub New(ByVal NetSelected As Providers)<br />
        Select Case NetSelected<br />
            Case Providers.DES<br />
                _CryptoService = New DESCryptoServiceProvider()<br />
            Case Providers.RC2<br />
                _CryptoService = New RC2CryptoServiceProvider()<br />
            Case Providers.Rijndael<br />
                _CryptoService = New RijndaelManaged()<br />
        End Select<br />
    End Sub<br />
<br />
    'Constructor for using a customized SymmetricAlgorithm class.<br />
    Public Sub New(ByVal ServiceProvider As SymmetricAlgorithm)<br />
        _CryptoService = ServiceProvider<br />
    End Sub<br />
<br />
    'Depending on the legal key size limitations of a specific CryptoService provider<br />
    'and length of the private key provided, padding the secret key with space character<br />
    'to meet the legal size of the algorithm.<br />
    Private Function GetLegalKey(ByVal Key As String) As Byte()<br />
        Dim sTemp As String<br />
        If (_CryptoService.LegalKeySizes.Length > 0) Then<br />
            Dim lessSize As Integer = 0<br />
            Dim moreSize As Integer = _CryptoService.LegalKeySizes(0).MinSize<br />
            'key sizes are in bits<br />
            Do While (Key.Length * 8 > moreSize)<br />
                lessSize = moreSize<br />
                moreSize += _CryptoService.LegalKeySizes(0).SkipSize<br />
            Loop<br />
            sTemp = Key.PadRight(moreSize / 8, " ")<br />
        Else<br />
            sTemp = Key<br />
        End If<br />
<br />
        'convert the secret key to byte array<br />
        Return ASCIIEncoding.ASCII.GetBytes(sTemp)<br />
    End Function<br />
<br />
    Public Function Encrypt(ByVal Source As String, ByVal Key As String) As String<br />
        Dim bytIn As Byte() = System.Text.ASCIIEncoding.ASCII.GetBytes(Source)<br />
        'create a MemoryStream so that the process can be done without I/O files<br />
        Dim ms As MemoryStream = New MemoryStream()<br />
<br />
        Dim bytKey As Byte() = GetLegalKey(Key)<br />
<br />
        'set the private key<br />
        _CryptoService.Key = bytKey<br />
        _CryptoService.IV = bytKey<br />
<br />
        'create an Encryptor from the Provider Service instance<br />
        Dim encrypto As ICryptoTransform = _CryptoService.CreateEncryptor()<br />
<br />
        'create Crypto Stream that transforms a stream using the encryption<br />
        Dim cs As CryptoStream = New CryptoStream(ms, encrypto, CryptoStreamMode.Write)<br />
<br />
        'write out encrypted content into MemoryStream<br />
        cs.Write(bytIn, 0, bytIn.Length)<br />
        cs.FlushFinalBlock()<br />
<br />
        'get the output and trim the '\0' bytes<br />
        Dim bytOut As Byte() = ms.GetBuffer()<br />
        Dim i As Integer = 0<br />
        For i = 0 To bytOut.Length<br />
            If bytOut(i) = 0 Then Exit For<br />
        Next<br />
<br />
        'convert into Base64 so that the result can be used in xml<br />
        Return System.Convert.ToBase64String(bytOut, 0, i)<br />
    End Function<br />
<br />
    Public Function Decrypt(ByVal Source As String, ByVal Key As String) As String<br />
        'convert from Base64 to binary<br />
        Dim bytIn As Byte() = System.Convert.FromBase64String(Source)<br />
        'create a MemoryStream with the input<br />
        Dim ms As MemoryStream = New MemoryStream(bytIn, 0, bytIn.Length)<br />
<br />
        Dim bytKey As Byte() = GetLegalKey(Key)<br />
<br />
        'set the private key<br />
        _CryptoService.Key = bytKey<br />
        _CryptoService.IV = bytKey<br />
<br />
        'create a Decryptor from the Provider Service instance<br />
        Dim encrypto As ICryptoTransform = _CryptoService.CreateDecryptor()<br />
<br />
        'create Crypto Stream that transforms a stream using the decryption<br />
        Dim cs As CryptoStream = New CryptoStream(ms, encrypto, CryptoStreamMode.Read)<br />
<br />
        'read out the result from the Crypto Stream<br />
        Dim sr As StreamReader = New StreamReader(cs)<br />
        Return sr.ReadToEnd()<br />
    End Function<br />
<br />
End Class<br />