VB.NET : RSA Encryption : Encryption not always encrypting at 128 Bits

Hi All,

I'm trying to encrypt a few details (4 variables to be exact) in this application that i'm creating using the RSA Encryption Method.

I can never seem to get it to encrypt all 4 correctly @ 128 bits, even though it says that the length of the encryption is 128 bits (tested using a MsgBox Feature)

The code seems fine to me... It comes back saying that it's encrypted at 128bits ok, but when decryption time comes, at least 1 of the 4 will cause an error in mscorlib.dll saying Bad Data on the line where the RSA.Decrypt method is called.

The Following is the Code of the clsEncryption.vb File

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Imports System.Security.Cryptography
Imports System.Text

Public Class clsEncryption

    Dim PlainText As Byte()
    Dim EncryptedText As Byte()
    Dim xmlKeys As String
    Dim xmlPublicKey As String

    Public Function ProcessEncryption(ByVal PrivateKey As String, ByVal PublicKey As String, ByVal Text As String)

        Try

            Dim RSA As RSACryptoServiceProvider = New RSACryptoServiceProvider

            RSA.FromXmlString(PublicKey)

            PlainText = (New UnicodeEncoding).GetBytes(Text)
            EncryptedText = RSA.Encrypt(PlainText, False)

            Dim FinalisedText As String = ""

            For i As Integer = 0 To EncryptedText.Length - 1
                FinalisedText += Chr(EncryptedText(i))
            Next i

            If FinalisedText.Length = 128 Then
                MsgBox("Encrypted @ 128 Bits OK", 64, "Encryption OK")
            Else
                MsgBox("Unable to Encrypt @ 128 Bits", 16, "Encryption Failed")
            End If

            Return FinalisedText

        Catch ex As Exception
            clsErrors.DisplayError(ex)
        End Try

    End Function

    Public Function ProcessDecryption(ByVal PrivateKey As String, ByVal PublicKey As String, ByVal EncryptedText As Byte())

        Try
            Dim RSA As RSACryptoServiceProvider = New RSACryptoServiceProvider

            RSA.FromXmlString(PrivateKey)

            PlainText = RSA.Decrypt(EncryptedText, False)

            Dim ProperText As String

            For i As Integer = 0 To (PlainText.Length - 1) Step 2
                ProperText += Chr(PlainText(i))
            Next i

            Return ProperText

        Catch ex As Exception
            clsErrors.DisplayError(ex)
        End Try

    End Function

    Public Function CreateKeys(ByVal Keys() As String)
        Dim rsa As New RSACryptoServiceProvider
        xmlKeys = rsa.ToXmlString(True)
        Keys(0) = xmlKeys
        xmlPublicKey = rsa.ToXmlString(False)
        Keys(1) = xmlPublicKey

        Return Keys

    End Function

End Class

******************************************

The Following is the code where the encryption process takes place

******************************************

    Private Sub btnSubmitAppDetails_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSubmitAppDetails.Click
        If txtSQLServer.Text = "" Then
            MsgBox("SQL Server Name Field Empty. Please Complete All Fields before Proceeding", 48, "SQL Server Field Empty")
            Exit Sub
        ElseIf txtSQLDatabase.Text = "" Then
            MsgBox("SQL Database Name Field Empty. Please Complete All Fields before Proceeding", 48, "SQL Database Name Field Empty")
            Exit Sub
        ElseIf txtSQLuser.Text = "" Then
            MsgBox("SQL Database User Name Field Empty. Please Complete All Fields before Proceeding", 48, "SQL Database User Name Field Empty")
            Exit Sub
        ElseIf txtSQLPassword.Text = "" Then
            MsgBox("SQL Database Password Field Empty. Please Complete All Fields before Proceeding", 48, "SQL Database Password Field Empty")
            Exit Sub
        End If

        Dim DBServer As String = txtSQLServer.Text
        Dim DBName As String = txtSQLDatabase.Text
        Dim DBUserName As String = txtSQLuser.Text
        Dim DBPassword As String = txtSQLPassword.Text

        lblStatus.Text = "Please Wait... Saving Data To Registry..."
        lblStatus.Update()
        lblStatus.Refresh()

        Dim Keys(1) As String

        Cryptography.CreateKeys(Keys)

        lblStatus.Text = "Please Wait... Creating Registry Keys..."
        lblStatus.Update()
        lblStatus.Refresh()
        RegKey = Registry.LocalMachine.CreateSubKey("SYSTEM\CurrentControlSet\Control\Class\{0F0F4125-DCDB-405E-AD8E-F0931279A240}\0000\AppData")
        RegKey.SetValue("PRKey", Keys(0))
        RegKey.SetValue("PUKey", Keys(1))

        lblStatus.Text = "Please Wait... Encrypting Details and Saving to System: 1 / 4..."
        lblStatus.Update()
        lblStatus.Refresh()
        DBServer = Cryptography.ProcessEncryption(Keys(0), Keys(1), DBServer)
        RegKey.SetValue("DBServer", DBServer)

        lblStatus.Text = "Please Wait... Encrypting Details and Saving to System: 2 / 4..."
        lblStatus.Update()
        lblStatus.Refresh()
        DBName = Cryptography.ProcessEncryption(Keys(0), Keys(1), DBName)
        RegKey.SetValue("DBName", DBName)

        lblStatus.Text = "Please Wait... Encrypting Details and Saving to System: 3 / 4..."
        lblStatus.Update()
        lblStatus.Refresh()
        DBUserName = Cryptography.ProcessEncryption(Keys(0), Keys(1), DBUserName)
        RegKey.SetValue("DBUser", DBUserName)

        lblStatus.Text = "Please Wait... Encrypting Details and Saving to System: 4 / 4..."
        lblStatus.Update()
        lblStatus.Refresh()
        DBPassword = Cryptography.ProcessEncryption(Keys(0), Keys(1), DBPassword)
        RegKey.SetValue("DBPass", DBPassword)

        lblStatus.Text = "Process Completed Successfully"
        lblStatus.Update()
        lblStatus.Refresh()

        RegKey.Close()

        Me.Dispose()

    End Sub

******************************************

The Following Code is where the Decryption takes place

******************************************

... ... ...

            'Decrypt Registry Data and Save to Global Variables

            RegKey = Registry.LocalMachine.OpenSubKey("SYSTEM\CurrentControlSet\Control\Class\{0F0F4125-DCDB-405E-AD8E-F0931279A240}\0000\AppData", False)

            Dim EncryptedVariable As Byte()
            Dim TextVariable As String

            Dim PrivateKey As String = RegKey.GetValue("PRKey")
            Dim PublicKey As String = RegKey.GetValue("PUKey")

            EncryptedVariable = System.Text.Encoding.Default.GetBytes(RegKey.GetValue("DBServer"))
            TextVariable = Cryptography.ProcessDecryption(PrivateKey, PublicKey, EncryptedVariable)
            SQLServer = TextVariable

            EncryptedVariable = System.Text.Encoding.Default.GetBytes(RegKey.GetValue("DBName"))
            TextVariable = Cryptography.ProcessDecryption(PrivateKey, PublicKey, EncryptedVariable)
            SQLDBName = TextVariable

            EncryptedVariable = System.Text.Encoding.Default.GetBytes(RegKey.GetValue("DBUser"))
            TextVariable = Cryptography.ProcessDecryption(PrivateKey, PublicKey, EncryptedVariable)
            SQLUser = TextVariable

            EncryptedVariable = System.Text.Encoding.Default.GetBytes(RegKey.GetValue("DBPass"))
            TextVariable = Cryptography.ProcessDecryption(PrivateKey, PublicKey, EncryptedVariable)
            SQLPassword = TextVariable

... ... ...

******************************************

If Anyone can provide some assistance into why it aint encrypting/decrypting correctly it'll be greatly appreciated

Many thanks in Advance

Kind Regards,

Ray.