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encrypt / decrypt text string in vb.net - VS 2005

I would like to ask from some help related to encryption / decryption.
Is it feasilbe to get some sample code of a small application that has
a textbox and two radio buttons that does the following:

1. enter text in box
2. select radio button "encrypt"
3. show encrypted text in text box or msgbox
4. select radio button "decrypt"
5. show decrypted text in text box or msgbox

Any help with sample code would be great.

Thank you!
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jeebukarthikeyan
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Mike Tomlinson
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Here is a very simple Encryption/Decryption class that works with Strings.  Simply pass in the string to encrypt/decrypt and the key that you want to use.

Imports System.IO
Imports System.Text
Imports System.Security.Cryptography

Public Class Crypto

    Private Shared DES As New TripleDESCryptoServiceProvider
    Private Shared MD5 As New MD5CryptoServiceProvider

    Public Shared Function MD5Hash(ByVal value As String) As Byte()
        Return MD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(value))
    End Function

    Public Shared Function Encrypt(ByVal stringToEncrypt As String, ByVal key As String) As String
        DES.Key = Crypto.MD5Hash(key)
        DES.Mode = CipherMode.ECB
        Dim Buffer As Byte() = ASCIIEncoding.ASCII.GetBytes(stringToEncrypt)
        Return Convert.ToBase64String(DES.CreateEncryptor().TransformFinalBlock(Buffer, 0, Buffer.Length))
    End Function

    Public Shared Function Decrypt(ByVal encryptedString As String, ByVal key As String) As String
        Try
            DES.Key = Crypto.MD5Hash(key)
            DES.Mode = CipherMode.ECB
            Dim Buffer As Byte() = Convert.FromBase64String(encryptedString)
            Return ASCIIEncoding.ASCII.GetString(DES.CreateDecryptor().TransformFinalBlock(Buffer, 0, Buffer.Length))
        Catch ex As Exception
            MessageBox.Show("Invalid Key", "Decryption Failed", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
        End Try
    End Function

End Class
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itortu
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ASKER

how the key is defined?
ASKER CERTIFIED SOLUTION
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Mike Tomlinson
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