CAPTCHA [VS 2005]

Image captcha(PictureBox pictureBoxCible, int nbCaractere, int Largeur, int Hauteur, out string captchaStr)
        {
            Random ran = new Random();

            captchaStr = "";
            
            string[] sArray = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "m", "n", 
                               "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",
                               "A", "B", "C", "D", "E", "F", "G", "H", "J", "K", "L", "M", "N", "P", 
                               "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z",
                               "0", "1", "2", "3", "4", "5", "6", "7", "8", "9"};
            
            for (int i = 0; i < nbCaractere; i++)
            {
                int intRandom = ran.Next(0, sArray.Length);

                captchaStr = captchaStr + sArray[intRandom];

                if (captchaStr.Length > 8)
                {
                    captchaStr = captchaStr.Remove(8, captchaStr.Length - 8);
                }                                
            }
            
            Graphics g = pictureBoxCible.CreateGraphics();

        //mesure de str
            SizeF sizeff = g.MeasureString(captchaStr, new Font("Arial", 25, FontStyle.Strikeout, GraphicsUnit.Pixel), 300);

       //rectangle aux dimensions de la chaine de caractere
            System.Drawing.Rectangle rect = new System.Drawing.Rectangle(0, 0, Largeur, Hauteur);  //new System.Drawing.Rectangle(0, 0, sizeff.Width, sizeff.Height);


            Bitmap b = new Bitmap(Largeur, Hauteur, System.Drawing.Imaging.PixelFormat.Format32bppPArgb);

      //graphics pour dessiner ds le bitmap
            Graphics gr = Graphics.FromImage(b);

      //dessin du background image
            HatchBrush hatchBrush = new HatchBrush(HatchStyle.Wave, Color.PowderBlue, Color.Black);

            gr.FillRectangle(hatchBrush, rect);

     //dessin des caratceres
            gr.DrawString(captchaStr, new Font("Arial", 30, FontStyle.Regular, GraphicsUnit.Point), Brushes.Yellow, 65, 0);
            gr.DrawString(captchaStr, new Font("Arial", 30, FontStyle.Regular, GraphicsUnit.Point), Brushes.Tomato, 67, 1);

            gr.DrawString("- - - - - ", new Font("Arial", 30, FontStyle.Bold, GraphicsUnit.Point), Brushes.Violet, 50, 4);
            gr.DrawString(" - - - - -", new Font("Arial", 30, FontStyle.Bold, GraphicsUnit.Point), Brushes.Thistle, 100, -7);

            return b;
        }