captcha | 易学教程

jquery .load dynamic image

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问题 Is there any way I can use the .load event(or any other jquery event) with a dynamic image such as this Whenever I try to use the .load or .get method to reload that page into the document it just come out as �� in Firefox and �PNG in internet explorer. What am I missing here? What would be the best way to do this? Overall what I'm trying to accomplish here is to reload the captcha.php file into a div when a link is clicked and have a different captcha image be shown without refreshing

Extracting a image from a WebBrowser Control

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问题 My aim is to extract an image from a loaded webbrowser control. // get the image link from the image element ID. string imageLink = wbVideos.Document.GetElementById("sbvdcapimg").GetAttribute("src").ToString(); //Download the image into a bitmap Bitmap image = new Bitmap(new System.IO.MemoryStream(new System.Net.WebClient().DownloadData(imageLink))); so the code works for most pictures, but i receive me a format error when i use it with the link below. The error is thrown when i parse this

Captcha encryption

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问题 I have created a captcha image making program with PHP <?php function word($n) { $consonants = "bcdfghjklmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ"; $vowels = "aeiou"; $word[1] = $consonants[rand(0, 41)]; $word[2] .= $vowels[rand(0, 4)]; $word[3] .= $consonants[rand(0, 41)]; $word[4] .= $consonants[rand(0, 41)]; return $word[$n]; } $xs = 550; $ys = 300; $im = imagecreatetruecolor($xs, $ys); $newim = imagecreatetruecolor($xs, $ys); imagettftext($im, $ys/5, rand(-10, 10), rand(0, 10), $ys/2, 0xFFFFFF,

CAPTCHA validation with JavaScript

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问题 I am trying to validate Captcha using JavaScript. But I could't find any resource about Client API's of Captcha. Do you have any documentation? 回答1: If you could validate the captcha through JavaScript that would mean the means of finding out the valid code would be readily available in the code that you're passing to the client, which would effectively invalidate the use for a captcha altogether. The only secure way to achieve this would be to send an AJAX request to the server, which would

Primefaces 5: captcha does not work for 'javax.servlet.ServletException: Expression cannot be null'

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问题 I have created a simple xhtml page with following code (like Primefaces showcase): <body> <div>My test</div> <h:form> <p:messages showDetail="true"/> <p:captcha label="Captcha" /> </h:form> </body> Loading this page, I get following exceptions: exception javax.servlet.ServletException: Expression cannot be null root cause javax.el.ELException: Expression cannot be null My scope is to use captcha component in a form and check if user checked it by a button (submit). This is the fullstack trace

Integrate CAPTCHA with a form

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问题 I am trying to integrate a captchia code with using a form. What I have is a basic format to where I was able to get the captcha part working on its own php page. Also I was able to display a form in its own php page. The problem I am having is I'm not sure how to get both parts working together. This is a snipit of what I have: <?php session_start(); if (isset($_POST['captcha'])) { $_SESSION['captcha'] = rand(0, 99999999999); } else { if ($_SESSION['captcha']!==$_POST['captcha']) { echo 're

Defeating spam registrations

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问题 I am trying to learn as much as possible about running a high-profile website. I designing some user registration screens and was thinking about the typical CAPTCHA, or annoying alternatives. In my opinion, having them either causes accessibility issues, or simply bothers potential customers and inhibits their registration process. My question is whether spambots recognize and trigger JavaScript events, such as the keydown or keypress event on an input field. From what I can gather, most bots

How to check if a user of my web application is trying to login with different credentials?

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问题 I'm trying from 3 days to make or find good way to detect if there is a user trying to login my web application with many login credentials or making flood attack, so I can show captcha as example in this cause in my login page, but with no luck. I can know if there is user with login username : "xyz" trying many times to login, but what if a user trying to login with many usernames like "xyz1" , "xyz2", "xyz3" , "admin", "administrator", "root" .... etc. Specially that user maybe trying with

Add Google Recaptcha on a SilverStripe form

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问题 I am trying to add Google Recaptcha to my custom SilverStripe form. I have generated Google public and private keys but I do not know where to put them to show a captcha on my website. Here is my current code: ContactPage class ContactPage extends Page { private static $db = array( 'TelCustomerSupport' => 'Varchar', 'TelProjectSupport' => 'Varchar', 'OfficeName' => 'Text', 'OfficeStreetAddress' => 'Text', 'OfficeAddressLocality' => 'Text', 'OfficePostalCode' => 'Varchar', 'OfficeMapLink' =>

Anti-Captcha Using Mouse detection

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问题 I want to know if it is possible to create a secure human detection mechanism (not using captcha) for a form with just javascript to detect mouse movement since jquery nor operating system code can move the mouse (so Im told). Here is my plan: With jQuery I can detect if the mouse has moved, and then allow a form to submit if it has. I already have cross site scripting enabled so no one can submit directly to the site outside of the webpage, and Im requiring javascript to sumbit the form. The