Captcha for ASP.NET AJAX

Overview

It is so easy to prevent your online forms from automated spam by simply adding RadCaptcha to your ASP.NET application. A flexible website security component, RadCaptcha will protect your registration, comment, poll, content submission, etc. It generates distorted images of letters and numbers that are easily decipherable to humans -- but not to spam bots. In essence, it allows you to focus on your code or content -- instead of on deleting spam.

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Features

• Major Modes for Protection
• Validation
• Flexible Layout
• Generate New Image
• Captcha Timeout
• Industry-best Cross-browser Support

• Major Modes for Protection

  Telerik RadCaptcha provides two major strategies for protection against automated form submissions For maximum security, by default, all of them are used.
  

  • Image with Modified Symbols (Captcha Image) – The image is displayed in a form, and the user is required to input the symbols in a textbox. The Image is generated with an HttpHandler.
  • Automatic Robots Discovery - this strategy uses predefined rules which decide whether the input comes from a robot or not. At this point, there are two implemented rules that could be applied either separately or simultaneously.

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• Validation

  The Captcha control by Telerik provides the ability to enable a  validation through the ValidationGroup property. If the user does not enter the right captcha symbols the validators will display an error message in the ValidationSummary.
  
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• Flexible Layout

  The Telerik ASP.NET Captcha allows for flexible layout customization. You can easily control the background, and the line noise of the Image by setting the respective values (None, Low, Medium, High or Extreme). Additionally, you have full control of the look of the captcha image, settings for fonts, number and set of characters, colors, etc. though some simple properties.

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• Generate New Image

  Telerik ASP.NET AJAX Captcha gives the possibility to refresh the image if the current one cannot be read. The distorted image can be reset so that a new one is generated.

  
  

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• Captcha Timeout

  The control also features a configurable settable timeout to help defeat those "human bot shops". It allows you to specify a maximum number of minutes the Captcha Image will be cached and valid. the presumption is that a human cannot input the fields in a form correctly for a time less than 3 seconds (this is set by default, and could be modified). If the submission is executed faster than the predefined value, it is assumed that the executor is a robot.

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• Industry-best Cross-browser Support

  The Telerik ASP.NET Captcha control supports all major browsers including Internet Explorer, Firefox, Safari, Opera and Google Chrome.

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