Generate random verification code for user login system

C#

Randomly generated code class: Validatecode.ashx

<%@ WebHandler language= "C #" class= "Validatecode"%> using System; Using System.Web; Using System.Drawing; Using System.Web.SessionState; To use a session in a generic handler, you must implement an interface public class Validatecode:ihttphandler,irequiressessionstate {

    public void ProcessRequest (HttpContext context)     {         context. Response.ContentType = "Image/jpeg";         String code = GETRNDSTR (); //Generate 4 random characters                 //record generated verification code          context. session["Code" = code;         using (Bitmap img = createimages (Code, "ch"))          {            img. Save (context. Response.outputstream, System.Drawing.Imaging.ImageFormat.Jpeg);        }    }

    public bool isreusable     {        get  & nbsp;      {            return False        }    }    //<summary>     ///digital random number    //</summary>    //<returns></returns>  & nbsp;  private String Getrndnum ()     {        String code = String. Empty;         random random = new random ();         for (int i = 0; i < 4; i++)         {&NB sp;           code + = random. Next (9);        }         return code;   &nbsp }    ///<summary>    ///  English random    //</summary>    //<returns></returns>     private String getrndstr ()      {        String vchar = "A,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x, Y,z ";         string[] Vcarray = Vchar.split (', ');         string checkcode = string. Empty;         Random rand = new Random ();         for (int i = 0; i < 4; i++)         {&NB sp;           int t = rand. Next (vcarray.length);             Checkcode + = vcarray[t];        }         return Checkcode;    }    //<summary>    //Chinese random    ///</ Summary>    ///<returns></returns>     private String getrndch ()      {        System.Text.Encoding GB = system.text.encoding.default;// Get GB2312 Encoding page (table)         object[] bytes = Createregioncode (4);//Born 4 random Chinese Chinese character coding          string[] str = new STRING[4];         System.Text.StringBuilder sb = new System.Text.StringBuilder ();         for (int i = 0; i < 4; i++)         {&NB sp;          //decoding Chinese characters according to Chinese character coding byte array              Str[i] = GB. GetString ((byte[]) Convert.changetype (Bytes[i], typeof (byte[)));             sb. Append (Str[i]. ToString ());        }         return sb. ToString ();    }    //<summary>    //Generate random Chinese characters    //</ Summary>    //<param name= "strlength" ></param>    //<returns ></returns>     private static object[] Createregioncode (int strlength)     {& nbsp;      //define a string array to store the constituent elements of the Chinese character coding         string[] RBase = new String[16] {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "B", "C", "D", "E", "F"};         random rnd = new Random ();         object[] bytes = new Object[strlength];

        for (int i = 0; i < strlength; i++)       & nbsp {           //Location code 1th bit              int r1 = rnd. Next (11, 14);             string str_r1 = Rbase[r1]. Trim ();            //Location Code 2nd digit              rnd = new Random (R1 * Unchecked ((int) DateTime.Now.Ticks) + i);             int R2;             if (r1 = =)              {                 r2 = rnd. Next (0, 7);            }             Else              {                 r2 = rnd. Next (0, 16);            }              string str_r2 = Rbase[r2]. Trim ();

           //Location Code 3rd bit              rnd = new Random (R2 * Unchecked ((int) DateTime.Now.Ticks) + i);//replace random seed              int r3 = rnd. Next (10, 16);             string str_r3 = Rbase[r3]. Trim ();

           //Location Code 4th digit              rnd = new Random (R3 * Unchecked ((int) DateTime.Now.Ticks) + i);             int R4;             if (r3 = = Ten)              {                 R4 = rnd. Next (1, 16);            }              else if (r3 = =)             {                 R4 = rnd. Next (0, 15);            }              Else             {                 R4 = rnd. Next (0, 16);            }              string str_r4 = Rbase[r4]. Trim ();            //Define two-byte variable storage generated random Chinese character location codes              byte byte1 = convert.tobyte (str_r1 + str_r2, 16);             byte Byte2 = convert.tobyte (Str_r3 + STR_R4, 16);

           //Storing two byte variables in a byte array              byte[] Str_r = new byte[] {byte1, byte2};

           //will produce a byte array of a Chinese character into the object array              bytes. SetValue (Str_r, i);        }         return bytes;    }    //<summary>    //Picture background + interference line    /// Lt;/summary>    //<param name= "Checkcode" ></param>    //< returns></returns>     Private Bitmap createimages (string checkcode, String type)      {        int step = 0;         if (type = = "ch")         {             Step = 5;//Chinese characters, boundary value bigger        }         int iwidth = (int) (Checkcode.length * (+ step));         System.Drawing.Bitmap image = new System.Drawing.Bitmap (iwidth, 33);         Graphics g = graphics.fromimage (image);         g.clear (Color.White);//clear background color          color[] C = {color.black, color.red, Color.darkblue, Color.green, Color.orange, Color.brown, Color.darkcyan, Color . Purple};//define random colors         string[] Font = {"Verdana", "Microsoft Sans Serif", "Comic S Ans MS "," Arial "," Song Body "};         Random rand = new Random ();

        for (int i = 0; i < i++)         {            int x1 = rand. Next (image. Width);             int x2 = rand. Next (image. Width);             int y1 = rand. Next (image. Height);             int y2 = rand. Next (image. Height);             G.drawline (New Pen (Color.lightgray, 1), X1, Y1, x2, y2);//Draw line        } by coordinates

        for (int i = 0; i < checkcode.length; i++)     & nbsp;   {            int cindex = rand. Next (7);             int findex = rand. Next (5);

            Font f = new System.Drawing.Font (Font[findex] , System.Drawing.FontStyle.Bold);             Brush B = new System.Drawing.SolidBrush (c[cindex ]);             int II = 4;             if ((i + 1)% 2 = = 0)              {                 II = 2;            }              g.drawstring (Checkcode.substring (i, 1), F, B, 3 + (I * (+ + Step)), ii);

} g.drawrectangle (New Pen (Color.Black, 0), 0, 0, image. Width-1, image.         HEIGHT-1);         System.IO.MemoryStream ms = new System.IO.MemoryStream ();     return image; } }

Page Call:

<tr>
<td> captcha: </td><td><input type= "text" id= "Txtcode" runat= "Server"/></td><td>
<br/></td>
</tr>

Generate random verification code for user login system