Re: .NET Encryption/Decryption Problem -- Pls help

From: Asaf Goldman (asafgo@hotmail.com)
Date: 08/26/02 

From: "Asaf Goldman" <asafgo@hotmail.com>
Date: Mon, 26 Aug 2002 10:49:38 +0200

Write
-------------------------------------------------------
<%@ Import Namespace="System.IO" %>
<%@ Import Namespace="System.Security.Cryptography" %>

<Script Runat="Server">

CONST DESKey As String = "ABCDEFGH"
CONST DESIV As String = "HGFEDCBA"

Function Convert2ByteArray( strInput As String ) As Byte()
  Dim intCounter As Integer
  Dim arrChar As Char()

  arrChar = strInput.ToCharArray()
  Dim arrByte( arrChar.Length - 1 ) As Byte
  For intCounter = 0 To arrByte.Length - 1
    arrByte( intCounter ) = Convert.ToByte( arrChar( intCounter ) )
  Next
  Return arrByte
End Function

Sub Button_Click( s As Object, e As EventArgs )
  Dim arrDESKey As Byte()
  Dim arrDESIV AS Byte()
  Dim arrInput As Byte()
  Dim objFileStream As FileStream
  Dim objDES As DESCryptoServiceProvider
  Dim objEncryptor As ICryptoTransform
  Dim objCryptoStream As CryptoStream

  arrDESKey = Convert2ByteArray( DESKey )
  arrDESIV = Convert2ByteArray( DESIV )
  arrInput = Convert2ByteArray( txtInput.Text )
  objDES = New DESCryptoServiceProvider()
  objEncryptor = objDES.CreateEncryptor( arrDESKey, arrDESIV )
  objFileStream = New FileStream( _
    MapPath( "secret.txt" ), _
    FileMode.Create, _
    FileAccess.Write )
  objCryptoStream = New CryptoStream( _
    objFileStream, _
    objEncryptor, _
    CryptoStreamMode.Write )
  objCryptoStream.Write( arrInput, 0, arrInput.Length )
  objCryptoStream.Close()
End Sub

</Script>

<html>
<head><title>SymmetricWrite.aspx</title></head>
<body>

<form Runat="Server">

<h2>DES Encryption</h2>

<b>Enter text to encrypt:</b>
<br>
<asp:TextBox
  id="txtInput"
  TextMode="Multiline"
  Columns="50"
  Rows="10"
  Runat="Server" />
<p>
<asp:Button
  Text="Encrypt!"
  OnClick="Button_Click"
  Runat="Server" />

</form>
</body>
</html>

Read------------------------------------------------------------------------
--------
<%@ Import Namespace="System.IO" %>
<%@ Import Namespace="System.Security.Cryptography" %>

<Script Runat="Server">

CONST DESKey As String = "ABCDEFGH"
CONST DESIV As String = "HGFEDCBA"

Sub Page_load
  DESDecrypt
End Sub

Function Convert2ByteArray( strInput As String ) As Byte()
  Dim intCounter As Integer
  Dim arrChar As Char()

  arrChar = strInput.ToCharArray()
  Dim arrByte( arrChar.Length - 1 ) As Byte
  For intCounter = 0 To arrChar.Length - 1
    arrByte( intCounter ) = Convert.ToByte( arrChar( intCounter ) )
  Next
  Return arrByte
End Function

Sub DESDecrypt
  Dim arrDESKey As Byte()
  Dim arrDESIV As Byte()
  Dim objFileStream As FileStream
  Dim objDES As DESCryptoServiceProvider
  Dim objDecryptor As ICryptoTransform
  Dim objCryptoStream As CryptoStream

  arrDESKey = Convert2ByteArray( DESKey )
  arrDESIV = Convert2ByteArray( DESIV )
  objDES = New DESCryptoServiceProvider
  objDecryptor = objDES.CreateDecryptor( arrDESKey, arrDESIV )
  objFileStream = New FileStream( _
    MapPath( "secret.txt" ), _
    FileMode.Open, _
    FileAccess.Read )
  objCryptoStream = New CryptoStream( _
    objFileStream, _
    objDecryptor, _
    CryptoStreamMode.Read )
   lblMessage.Text = New StreamReader( objCryptoStream ).ReadToEnd()
  objFileStream.Close
End Sub

</Script>

<html>
<head><title>SymmetricRead.aspx</title></head>
<body>

<h2>DES Decryption</h2>

<b>Decrypted Text:</b>
<p>
<asp:Label
  ID="lblMessage"
  Runat="Server" />

</body>
</html>

"FOB" <fob_in_states@yahoo.com> wrote in message
news:OCPus8ITCHA.4240@tkmsftngp08...
> Hello geeks,
> I am working on some server side infrastructure where I need to encrypt
some
> data and send it to the client so that the client could send that data
back
> to me for identification purposes. I am trying to use .NET cryptography
> classes but I am running into some problem. Probably problem is with
> DESCryptoServiceProvider or I am not able to accurately convert from
string
> to byte array and vice vera.
>
> At the end, I dont receive the actual string that I encrypted, rather the
> string is truncated, means loss of data. If I encrypt the string
> "01234567890123456789", I receive only "01234567" !!!!
>
> I would greatly appreciate if someone could point out the problem.
>
> Following is the code that I am using:
>
> private void button1_Click(object sender, System.EventArgs e)
> {
> Byte[] arrKey ;
> arrKey = GetByteArray(txtKeyPassword.Text) ;
>
> Byte[] arrIV ;
> arrIV = GetByteArray(txtIVPassword.Text) ;
>
> // Data to encrypt
> string strData = "01234567890123456789" ;
>
> // Convert string data to byte array
> System.Text.UTF8Encoding objEncoding = new System.Text.UTF8Encoding() ;
> Byte[] arrUTF8 = objEncoding.GetBytes(strData) ;
>
> // Encrypt byte array
> DESCryptoServiceProvider objDES = new DESCryptoServiceProvider() ;
> MemoryStream objMemoryStream = new MemoryStream() ;
> CryptoStream objCryptoStream = new CryptoStream( objMemoryStream,
> objDES.CreateEncryptor(arrKey, arrIV),
> CryptoStreamMode.Write) ;
> objCryptoStream.Write(arrUTF8, 0, arrUTF8.Length) ;
> objCryptoStream.Flush() ;
>
> Byte[] arrEncryptedData = objMemoryStream.ToArray() ;
> string strEncryptedData = Convert.ToBase64String(arrEncryptedData) ;
>
> objCryptoStream.Close() ;
> objMemoryStream.Close() ;
>
> // Decrypt Data.
> // First conver the user token from Base64 to byte array
> // then decrypt the data.
> Byte[] arrEncryptedData2 = Convert.FromBase64String(strEncryptedData) ;
> objMemoryStream = new MemoryStream() ;
> objCryptoStream = new CryptoStream( objMemoryStream,
> objDES.CreateDecryptor(arrKey, arrIV),
> CryptoStreamMode.Write) ;
> objCryptoStream.Write(arrEncryptedData2, 0, arrEncryptedData2.Length) ;
> objCryptoStream.Flush() ;
>
> // Get the byte array.
> Byte[] arrDecryptedData = objMemoryStream.ToArray() ;
>
> // Convert the array to string
> string strDecryptedData = objEncoding.GetString(arrDecryptedData) ;
> }
>
> private Byte[] GetByteArray(string r_strData)
> {
> Byte[] arrByte = new Byte[r_strData.Length] ;
> Encoding objEncoding = System.Text.Encoding.UTF8 ;
> arrByte = objEncoding.GetBytes(r_strData) ;
> return arrByte ;
> }
>
> Thanks,
> FOB
>
>
>

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