Public Function CreateImage(ByVal path As String, ByVal height As Integer, ByVal width As Integer) As String

        Dim r As New Random

        Dim salt As String = CreateSalt(4)

        Dim bmp As New Bitmap(width, height, PixelFormat.Format24bppRgb)

        Dim g As Graphics = Graphics.FromImage(bmp)

        g.TextRenderingHint = TextRenderingHint.AntiAlias

        g.Clear(Color.Black)

        g.DrawRectangle(Pens.White, 1, 1, width - 3, height - 3)

        g.DrawRectangle(Pens.Black, 0, 0, width, height)

        Dim mymat As New System.Drawing.Drawing2D.Matrix

        Dim i As Integer

        For i = 0 To Len(salt) – 1

            mymat.Reset()

            mymat.RotateAt(r.Next(-30, 0), New PointF(width * (0.12 * i), height * 0.5))

            g.Transform = mymat

g.DrawString(salt.Chars(i), New Font("Comic Sans MS", 15, FontStyle.Italic), SystemBrushes.ActiveCaptionText, width * (0.12 * i), height * 0.5) 'draw the text on our(Image)

            g.ResetTransform()

        Next

        bmp.Save(path, ImageFormat.Gif)

        g.Dispose()

        bmp.Dispose()

        Return salt

    End Function

    Public Function CreateSalt(ByVal size As Integer) As String

        Dim rng As New RNGCryptoServiceProvider

        Dim buff(size) As Byte

        rng.GetBytes(buff)

        Return Convert.ToBase64String(buff)

    End Function

Name = “lblMessage”

Text =””

Name = “TextBox1”

Tex = “”

Name = “btnRegister”

Text = “Check”

If Not Page.IsPostBack Then

Dim verify As New verification

Dim salt As String = verify.CreateImage(Server.MapPath(".\Random.gif"), 100, 200)

Image.ImageUrl = Server.MapPath(".\Random.gif")

Session.Add("salt", salt)

Dim params As System.Collections.Specialized.NameValueCollection

params = Request.QueryString()

If params.Count > 0 Then lblMessage.Text = params.Item("reason")

End If 

If Not TextBox1.Text.Equals(Session.Item("salt")) Then

            Response.Redirect(Request.Url.ToString & "?reason=The Strings did not match")            Else

            lblMessage.Text = "You correctly type the characters shown in the image"

End If