PERKEMBANGAN TEKNOLOGI | New Captcha Technology, "Captcha" Robot Hackers

What Captcha is
My friend, If we talk about "captcha" don’t ever think about “cap jay” (chinese food) in your mind, hehehe.. of course it’s different.

CAPTCHA, an acronym for Completely Automated Public Turing test to tell Computers and Humans Apart. A Captcha is usually a graphic image with a series of distorted letters on an equally distorted or multicolored background.

The technology is used mostly to block spammers and bots that try to automatically harvest email addresses or try to automatically sign up for or make use of blog, Web sites, or forums. Captcha technology is easy to implement, but requires some knowledge of hypertext preprocessor (PHP) or other Web scripting languages. Captcha, whose users include Yahoo and Google using algorithm to blocks automated systems, which can't read the distorted letters in the graphic.

Cracking the algorithm won't make the CAPTCHA vulnerable, since the algorithm is only used for generating the random series of letters and numbers in the image. The system works because humans and computers process strings of characters differently.

In my conclusion, Captcha is a program that protects websites against bots by generating and grading tests that humans can pass but current computer programs cannot. For example, humans can read distorted text as the one shown below, but current computer programs can't:

The Problem
We see the popular "captcha" security mechanism often - wavy letters websites ask us to type into a box. It's used by web pages and newsletter sign-up forms to prevent computer robots from hacking into servers and databases. But these codes, which are becoming increasingly complicated for an average person to use, are not immune to security holes.Sometimes the characters are so distorted that they can't even be recognized by people with good vision, let alone visually handicapped individuals. Depending on local regulations for handicapped access to Web sites, this can also be a compliance issue for some Web-based businesses.


New Solution For Captcha Technology
A research project led by Prof. Danny Cohen-Or of Tel Aviv University's Blavatnik School of Computer Sciences demonstrates how a new kind of video captcha code appears to be harder to outsmart. The foundation of the work, presented at a recent SIGGRAPH conference, is really pure research, says Prof. Cohen-Or, but it opens the door so security scientists can think a little differently.

"Humans have a very special skill that computer bots have still not been able to master," says Prof. Cohen-Or. "We can see what's called an 'emergence image' - an object on a computer screen that becomes recognizable only when it's moving - and identify this image in a matter of seconds. While a person can't 'see' the image as a stationary object on a mottled background, it becomes part of our gestalt as it moves, allowing us to recognize and process it".

In the new research paper, co-authored with colleagues in Taiwan, Saudi Arabia and India, Prof. Cohen-Or describes a synthesis technique that generates pictures of 3-D objects, like a running man or a flying airplane. This technique, he says, will allow security developers to generate an infinite number of moving "emergence" images that will be virtually impossible for any computer algorithm to decode. (LS/WIKI)

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