What is Captcha?

I am very confident that Buddy Blogger might have heard or seen / read the word "CAPTCHA". Maybe between Buddy Blogger there wondering, What is CAPTCHA?

CAPTCHA stands for Automated Public Turing test to tell Computers and Humans Apart. The term was coined by Luis von Ahn, Manuel Blum, Nicholas J. Hopper, and John Langford in 2000. CHAPTCHA is the type of response test used in the computing world that aims to ensure that the user is human or a human, and not a robot. The process usually involves a server that asks the user to complete a simple test that has been identified by the server. In this case, the other computer is assumed not to be able to solve the test in question, so that every user who enters the right solution suspected as a human being. A common type of CAPTCHA requires the user to type letters and or numbers of the distorted image that appears on the screen.

There may be among the bloggers who are wondering, why must use a CAPTCHA? Actually what CAPTCHA fungi? Here are some of the functions of the CAPTCHA.

Preventing Spam Comments on Blog

As we all know, there are some who like to send comments Blogger false. This is done using a program. Usually the goal is to increase rankings on search engines. This is called comment spam. Here, the role CAPTCHA is required. By using CAPTCHA, only humans can enter comments on the blog. No need to make users register before they enter comments.

Protecting Registration Site

Some companies (Yahoo, Microsoft, etc.) offers a free email service. Until a few years ago, most of these services suffer from certain types of attack: "bots" that would apply to thousands of email accounts every minute. The solution to this problem is to use a CAPTCHA to ensure that only people who will get an email account. In general, free services should be protected with a CAPTCHA to prevent abuse by automated programs.

Preventing Dictionary Attacks

In addition to the above, the CAPTCHA can also be used to prevent dictionary attacks in password systems. The idea is simple: prevent a computer from being able to iterate through the entire space of passwords by requiring to solve a CAPTCHA after a failed login.

Search Engine Bot.

Worms and Spam

CAPTCHAs also offer a reasonable solution against email worms and spam: ". I will only receive emails if I knew there was another man behind a computer" Some companies are already marketing this idea.

Once we know the function, now we will discuss how the application of a CAPTCHA to the website.

If your website needs protection from spammers, you can use the CAPTCHA. But in its use, there are some guidelines is highly recommended, among other things:

Accessibility

Must be accessible CAPTCHA, CAPTCHAs based solely on reading text - or a visual-perception tasks - prevent the robot or machine from accessing the protected resource. In addition to visual form, now also exist in the form of CAPTCHAs audio. This is done to make it easier for visually impaired users.

Security Image Image

From the text should be distorted randomly before being presented to the user. Many implementations of CAPTCHA using distorted text, or text with only minor distortion. This implementation is vulnerable to simple automated attacks.

Security Script

Building a secure CAPTCHA is not easy. In addition to making images unreadable by computers, the system must ensure that there is no easy way around it at the script level.

While it seems safe, a CAPTCHA still have gaps that may still be penetrated, including:

Exploiting bugs in the implementation that allows an attacker to completely bypass the CAPTCHA

Increasing character recognition software, or

Using cheap manpower to process the test.

Blogger pal, we have discussed about the function, installation guidelines, until the gap is probably impenetrable. Hopefully a little and ugly graffiti could be useful for us all. Please be corrected, and do not forget to leave a comment.

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