Captcha Cracking Javascript

Posted on 31.08.201922.08.2017by admin

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Javascript Captcha Code

Actually, someone already implemented a greasemonkey script to solve an OCR. It's written in Javascript, and is very specific (built to solve only one site's captcha). Here's an article about it: And here's the source (cached version). PWNtcha continually reports successful cracks of various captchas on the web using OCR algos and backend systems. What is pretty amazing though is that now you can even crack the images using JavaScript and Canvas. ShaunF wrote a GreaseMonkey script that automatically solves captchas of the file. Personally, if I was a spammer, I’d be comforted by the knowledge that my CAPTCHA crackers were adorned in jacket and tie and overseen by an attractive supervisor in a pants suit. But I digress. I thought it would be interesting to actually take up this service and see just how efficient outsourced CAPTCHA cracking can be.

This page explains how to display and customize the reCAPTCHA v2 widget on your webpage.

To display the widget, you can either:

Automatically render the widget or

See Configurations to learn how to customize your widget. For example, you may want to specify the language or theme for the widget.

See Verifying the user's response to check if the user successfully solved the CAPTCHA.

Javascript Captcha Code

Automatically render the reCAPTCHA widget

The easiest method for rendering the reCAPTCHA widget on your page is to include the necessary JavaScript resource and a g-recaptcha tag. The g-recaptcha tag is a DIV element with class name 'g-recaptcha' and your site key in the data-sitekey attribute:

The script must be loaded using the HTTPS protocol and can be included from any point on the page without restriction. Built to spill nothing wrong with love zipper bag.

Explicitly render the reCAPTCHA widget

Deferring the render can be achieved by specifying your onload callback function and adding parameters to the JavaScript resource.

Specify your onload callback function. This function will get called when all the dependencies have loaded.
Insert the Javascript resource, setting the onload parameter to the name of your onload callback function and the render parameter to explicit. When your callback is executed, you can call the grecaptcha.render method from the Javascript API.
Note: your onload callback function must be defined before the reCAPTCHA API loads. To ensure there are no race conditions:
- order your scripts with the callback first, and then reCAPTCHA
- use the async and defer parameters in the script tags

Configuration

JavaScript resource (api.js) parameters

Parameter	Value	Description
onload	Optional. The name of your callback function to be executed once all the dependencies have loaded.
render	explicit onload	Optional. Whether to render the widget explicitly. Defaults to onload, which will render the widget in the first `g-recaptcha` tag it finds.
hl	See language codes	Optional. Forces the widget to render in a specific language. Auto-detects the user's language if unspecified.

g-recaptcha tag attributes and grecaptcha.render parameters

g-recaptcha tag attribute	grecaptcha.render parameter	Value	Default	Description
data-sitekey	sitekey	Your sitekey.
data-theme	theme	dark light	light	Optional. The color theme of the widget.
data-size	size	compact normal	normal	Optional. The size of the widget.
data-tabindex	tabindex	0	Optional. The tabindex of the widget and challenge. If other elements in your page use tabindex, it should be set to make user navigation easier.
data-callback	callback	Optional. The name of your callback function, executed when the user submits a successful response. The `g-recaptcha-response` token is passed to your callback.
data-expired-callback	expired-callback	Optional. The name of your callback function, executed when the reCAPTCHA response expires and the user needs to re-verify.
data-error-callback	error-callback	Optional. The name of your callback function, executed when reCAPTCHA encounters an error (usually network connectivity) and cannot continue until connectivity is restored. If you specify a function here, you are responsible for informing the user that they should retry.

JavaScript API

Method	Description
grecaptcha.render( parameters )	Renders the container as a reCAPTCHA widget and returns the ID of the newly created widget. container The HTML element to render the reCAPTCHA widget. Specify either the ID of the container (string) or the DOM element itself. parameters An object containing parameters as key=value pairs, for example, {'sitekey': 'your_site_key', 'theme': 'light'}. See grecaptcha.render parameters.
grecaptcha.reset( )	Resets the reCAPTCHA widget. opt_widget_id Optional widget ID, defaults to the first widget created if unspecified.
grecaptcha.getResponse( opt_widget_id )	Gets the response for the reCAPTCHA widget. opt_widget_id Optional widget ID, defaults to the first widget created if unspecified.

Examples

Explicit rendering after an onload callback

Explicit rendering for multiple widgets