Perfect php code for generating verification Codes

This article introduces a very good php program for generating verification codes. First, when the user requests HTTP, the server creates a unique sessionid, which is the session ID, then, start the GD library or imagemagick painting tools, write the random characters generated by the program to an image, and display them to the client. Then, the user inputs and submits the data, then, our program saves the verification code in the session for comparison, so that the verification code is generated and verified.

• Create a PHP file captcha_code_file.php

The Code is as follows:

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// Enable the session first Session_start (); // Define the front-end verification code length and width $ Image_width = 120; $ Image_height = 40; $ Characters_on_image = 6; $ Font = './monofont. ttf '; // The characters that can be used in the CAPTCHA code. // Avoid confusing characters (l 1 and I for example) $ Possible_letters = '23456789bcdfghjkmnpqrstvwxyz '; $ Random_dots = 10; $ Random_lines = 30; $ Captcha_tex_color = "0x142864 "; $ Captcha_noice_color = "0x142864 "; // Define the string to generate the verification code $ Code = ''; $ I = 0; While ($ I <$ characters_on_image ){ $ Code. = substr ($ possible_letters, mt_rand (0, strlen ($ possible_letters)-1), 1 ); $ I ++; } $ Font_size = $ image_height * 0.75; $ Image = @ imagecreate ($ image_width, $ image_height ); /* Setting the background, text and noise colours here */ $ Background_color = imagecolorallocate ($ image, 255,255,255 ); $ Arr_text_color = hexrgb ($ captcha_text_color ); $ Text_color = imagecolorallocate ($ image, $ arr_text_color ['red'], $ Arr_text_color ['green'], $ arr_text_color ['blue']); $ Arr_noice_color = hexrgb ($ captcha_noice_color ); $ Image_noise_color = imagecolorallocate ($ image, $ arr_noice_color ['red'], $ Arr_noice_color ['green'], $ arr_noice_color ['blue']); /* Generating the dots randomly in background */ For ($ I = 0; $ I <$ random_dots; $ I ++ ){ Imagefilledellipse ($ image, mt_rand (0, $ image_width ), Mt_rand (0, $ image_height), 2, 3, $ image_noise_color ); } /* Generating lines randomly in background of image */ For ($ I = 0; $ I <$ random_lines; $ I ++ ){ Imageline ($ image, mt_rand (0, $ image_width), mt_rand (0, $ image_height ), Mt_rand (0, $ image_width), mt_rand (0, $ image_height), $ image_noise_color ); } /* Create a text box and add 6 letters code in it */ $ Textbox = imagettfbbox ($ font_size, 0, $ font, $ code ); $ X = ($ image_width-$ textbox [4])/2; $ Y = ($ image_height-$ textbox [5])/2; Imagettftext ($ image, $ font_size, 0, $ x, $ y, $ text_color, $ font, $ code ); /* Show captcha image in the page html page */ Header ('content-Type: image/jpeg '); // defining the image type to be shown in browser widow Imagejpeg ($ image); // showing the image Imagedestroy ($ image); // destroying the image instance // Set the session for verification $ _ SESSION ['6 _ letters_code '] = $ code; Function hexrgb ($ hexstr) { $ Int = hexdec ($ hexstr ); Return array ("red" => 0xFF & ($ int> 0x10 ), "Green" => 0xFF & ($ int> 0x8 ), "Blue" => 0xFF & $ int ); }

Index. php

The Code is as follows:

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<? Php Session_start (); If (isset ($ _ REQUEST ['submit ']) { // Code for check server side validation If (empty ($ _ SESSION ['6 _ letters_code ']) | Strcasecmp ($ _ SESSION ['6 _ letters_code '], $ _ POST ['6 _ letters_code'])! = 0) { $ Msg = "the verification code you entered is incorrect. Please enter it again! "; } Else { Echo "you entered the correct one! "; // Captcha verification is Correct. Final Code Execute here! } } ?> <Style type = "text/css"> . Table { Font-family: Arial, Helvetica, sans-serif; Font-size: 12px; Color: #333; Background-color: # E4E4E4; } . Table td { Background-color: # F8F8F8; } </Style> <Form action = "" method = "post" name = "form1" id = "form1"> <Table width = "400" border = "0" align = "center" cellpadding = "5" cellspacing = "1"> <? Php if (isset ($ msg) {?> <Tr> <Td colspan = "2" align = "center" valign = "top"> <? Php echo $ msg;?> </Td> </Tr> <? Php }?> <Tr> <Td align = "right" valign = "top"> Verification Code Demo: </td> <Td> "Id = 'captchaimg 'onclick =" refreshCaptcha (); "> <br> <Label for = 'message'> enter the verification code: </label> <Br> <Input id = "6_letters_code" name = "6_letters_code" type = "text"> <Br> If not, <a href = 'javascript: refreshCaptcha (); '> click me </a> to refresh it! </P> </td> </Tr> <Tr> <Td> & nbsp; </td> <Td> <input name = "Submit" type = "submit" onclick = "return validate ();" value = "Submit"> </td> </Tr> </Table> </Form> <Script type = 'text/javascript '> // Define the refresh request Function refreshCaptcha () { Var img = document. images ['captchaimg ']; Img. src = img. src. substring (0, img. src. lastIndexOf ("? ") + "? Rand = "+ Math. random () * 1000; } </Script>