A stable php login system verification code

A stable php login system verification code

Session_start (); $ Type = 'GIF '; $ Width = 56; $ Height = 22; Header ("Content-type: image/". $ type ); Srand (double) microtime () * 1000000 ); $ Randval = randStr (4, "NUMBER "); If ($ type! = 'GIF' & function_exists ('imagecreatetruecolor ')){ $ Im = @ imagecreatetruecolor ($ width, $ height ); } Else { $ Im = @ imagecreate ($ width, $ height ); } $ R = Array (225,211,255,223 ); $ G = Array (225,236,237,215 ); $ B = Array (225,236,166,125 ); $ Key = rand (0, 3 ); $ BackColor = ImageColorAllocate ($ im, $ r [$ key], $ g [$ key], $ B [$ key]); // background color (random) $ BorderColor = ImageColorAllocate ($ im, 0, 0, 0); // border color $ PointColor = ImageColorAllocate ($ im, 255,170,255); // vertex color @ Imagefilledrectangle ($ im, 0, 0, $ width-1, $ height-1, $ backColor); // background position @ Imagerectangle ($ im, 0, 0, $ width-1, $ height-1, $ borderColor); // border position $ StringColor = ImageColorAllocate ($ im, 153 ); For ($ I = 0; $ I <= 100; $ I ++ ){ $ PointX = rand (2, $ width-2 ); $ PointY = rand (2, $ height-2 ); @ Imagesetpixel ($ im, $ pointX, $ pointY, $ pointColor ); } @ Imagestring ($ im, 16, 10, 2, $ randval, $ stringColor ); $ ImageFun = 'image'. $ type; $ ImageFun ($ im ); @ ImageDestroy ($ im ); $ _ SESSION ['validatecode'] = $ randval; // Generate a random string Function randStr ($ len = 6, $ format = 'all '){ Switch ($ format ){ Case 'all ': $ Chars = 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789 '; break; Case 'char ': $ Chars = 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxy'; break; Case 'number ': $ Chars = '20140901'; break; Default: $ Chars = 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789 '; Break; } $ String = ""; While (strlen ($ string) <$ len) $ String. = substr ($ chars, (mt_rand () % strlen ($ chars), 1 ); Return $ string; } ?>