private void Page_Load(object sender, System.EventArgs e)

              {

                     Response.Cache.SetCacheability(HttpCacheability.NoCache);

                     Response.Clear();   

                     string StrPass = Request.QueryString["pass"];   

                     if ((StrPass != null)&&(StrPass != ""))

                     {

                           try

                           {

                                  if(StrPass.Length>40)

                                  {

                                         PaintError("طول ورودی نادرست است");   

                                  }

                                  string Str = "";

                                  int i = CalcStrength(StrPass,out Str);

                                  MyPaint(i,Str);                                

                           }

                           catch

                           {

                                  PaintError("خطا در فراخوانی تابع");

                           }   

                     }

                     else

                     {

                           PaintError("خطا ورودی تهی");

                     }

              }  

              private void MyPaint(int h,string StrMsg)

              { 

                     Bitmap picture = new Bitmap(280, 15);

                     System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(picture);                                         

                     int i, j; 

                     for (i = 0; i < 15; i++)

                     {

                           for (j = 0; j < 80; j++)

                           {

                                  picture.SetPixel(79 - j, i, Color.FromArgb(iRed(h, j), iGreen(h, j), 25));

                           }

                     } 

                     Pen pen = new Pen(Color.FromArgb(192,213,244));

                     Rectangle rect = new Rectangle(79,0,280,15);

                     SolidBrush b = new SolidBrush(Color.FromArgb(192,213,244));

                     SolidBrush blue = new SolidBrush(Color.Blue);                    

                     g.DrawRectangle(pen, rect);

                     g.FillRectangle(b, rect);

                     Font Font1 = new Font("tahoma", 8, System.Drawing.FontStyle.Regular);              

                     System.Drawing.StringFormat MyAlignment = new StringFormat();

                     MyAlignment.Alignment = StringAlignment.Far; 

                     g.DrawString(StrMsg, Font1, Brushes.Black, 250, 0, MyAlignment);

                     Response.ContentType = "image/jpg";

                     picture.Save(Response.OutputStream,System.Drawing.Imaging.ImageFormat.Jpeg);

                     g.Dispose();

                     picture.Dispose(); 

              }

              private void PaintError(string StrErr)

              { 

                     Bitmap picture = new Bitmap(280, 15);

                     System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(picture); 

                     Pen pen = new Pen(Color.FromArgb(192,213,244));

                     Rectangle rect = new Rectangle(0,0,280,15);

                     SolidBrush b = new SolidBrush(Color.FromArgb(192,213,244));

                     SolidBrush blue = new SolidBrush(Color.Blue);                    

                     g.DrawRectangle(pen, rect);

                     g.FillRectangle(b, rect); 

                     Font Font1 = new Font("tahoma", 8, System.Drawing.FontStyle.Regular);              

                     System.Drawing.StringFormat MyAlignment = new StringFormat();

                     MyAlignment.Alignment = StringAlignment.Far; 

                     g.DrawString(StrErr, Font1, Brushes.Black, 250, 0, MyAlignment);  

                     Response.ContentType = "image/jpg";

                     picture.Save(Response.OutputStream,System.Drawing.Imaging.ImageFormat.Jpeg);

                     g.Dispose();

                     picture.Dispose(); 

              }

              int iRed(int h,int i)

              {           

                     int iout = 255 - ((h / 20) * i);

                     if (iout <= 0) iout = 0;

                     return iout;

              }

              int iGreen(int h, int i)

              {

                     int iout = 1 + ((h / 10) * i);

                     if (iout >= 255) iout = 255;

                     return iout;           

              } 

              private int CalcStrength(string StrIN,out string StrOUT)

              {                       

                     StrOUT = "";

                     string StrChk = CheckSpecialCase(StrIN);

                     if (StrChk != "ok")

                     {                         

                           StrOUT = StrChk;

                           return 1;

                     }                     

                     int b1, b2, b3, b4;

                     double d1, d2, d3, S; 

                     string SrtLowercase = "abcdefghijklmnopqrstuvwxyz";

                     string SrtUpperrcase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

                     string StrSpecialChars = @"~`!@#$%^&*()_+-=,<.>/?':;|\]{}[" + "\"" ;

                     string StrNumbers = "0123456789";                         

                     char[] ArrLowerCase = new char[] { };

                     char[] ArrUppercase = new char[] { };

                     char[] ArrSpecialChars = new char[] { };

                     char[] ArrNumbers = new char[] { }; 

                     ArrLowerCase = SrtLowercase.ToCharArray();

                     ArrUppercase = SrtUpperrcase.ToCharArray();

                     ArrSpecialChars = StrSpecialChars.ToCharArray();

                     ArrNumbers = StrNumbers.ToCharArray(); 

                     b1 = StrIN.IndexOfAny(ArrLowerCase);

                     b2 = StrIN.IndexOfAny(ArrUppercase);

                     b3 = StrIN.IndexOfAny(ArrSpecialChars);

                     b4 = StrIN.IndexOfAny(ArrNumbers); 

                     S = 0; 

                     if (b1 >= 0) S += 26;

                     if (b2 >= 0) S += 26;

                     if (b3 >= 0) S += 32;

                     if (b4 >= 0) S += 10;           

                     d1 = (double)(StrIN.Length);

                     d2 = System.Math.Log10(S) * d1 ;

                     d3 = 30 + (2.1) * (d2 - 7);

                     if (d3 <= 0) d3 = 1;           

                     d2 = System.Math.Round(d2);

                     d3 = System.Math.Round(d3); 

                     if(d3<1) d3=1; 

                     StrOUT = AppraiseStrength((int)(d3));

                     return ((int)(d3));

              }

              private string CheckSpecialCase(string StrIn)

              {

                     string StrLower = StrIn.ToLower();

                     if (StrIn.Length < 5) return "کوتاهی طول گذرواژه";

                     if (StrIn.Length > 19) return "ok"; 

                     string[] Str1 = new string[] { "test", "admin", "administrator",                                                                             

                     "pass", "password", "user", "pa$$vvord" };

                     for (int i = 0; i < Str1.Length; i++)

                     {

                           if (StrLower == Str1[i].ToString()) return "قابل حدس";

                     } 

                     string StrKeyboard = "qwertyuiop[]asdfghjkl;'zxcvbnm,./,mnbvcxz';lkjhgfdsa[poiuytrewq";

                     if (StrKeyboard.IndexOf(StrLower)>0) return "توالی صفحه کلید";             

                     int  j, k, p1, p2;

                     p1 = 0;

                     p2 = 0;

                     char[] ArrTest = new char[] { };

                     ArrTest = StrIn.ToCharArray();

                     for (j = 0; j < ArrTest.Length - 1; j++)

                     {

                           for (k = j + 1; k < ArrTest.Length; k++)

                           {

                                  int d1 = System.Math.Abs(ArrTest[j] - ArrTest[k]);

                                  int d2 = System.Math.Abs(j - k);

                                  if ((d1 == 1)&&(d2 == 1)) p1++;

                                  if ((d1 == 0) && (d2 == 1)) p2++;

                           }

                     } 

                     if (p1 >= 3) return "استفاده از کاراکترهای متوالی";

                     if (p2 >= 3) return "استفاده از کاراکترهای یکسان";                                

                     return "ok";

              }  

              private string AppraiseStrength(int i)

              {

                     if (i<=5) return "غیر قابل قبول";

                     if ((i>5)&&(i<=10)) return "بسیار ضعیف";

                     if ((i>10)&&(i<=20)) return "ضعیف";

                     if ((i>20)&&(i<=50)) return "متوسط";

                     if ((i>50)&&(i<=70)) return "قوی";

                     if (i>70) return "بسیار قوی";   

                     return "خطا در مقدار ورودی";

              }