Tips & Tricks - CAPTCHA

What is CAPTCHA and How it Works? CAPTCHA or Captcha (pronounced as cap-ch-uh) which stands for “Completely Automated Public Turing test to tell Computers and Humans Apart” is a type of challenge-response test to ensure that the response is only generated by humans and not by a computer. In simple words, CAPTCHA is the word verification test that you will come across the end of a sign-up form while signing up for Gmail or Yahoo account. The following image shows the typical samples of CAPTCHA. Almost every Internet user will have an experience of CAPTCHA in their daily Internet usage, but only a few are aware of what it is and why they are used. So in this post you will find a detailed information on how CAPTCHA works and why they are used. What Purpose does CAPTCHA Exactly Serve? CAPTCPA is mainly used to prevent automated software (bots) from performing actions on behalf of actual humans. For example while signing up for a new email account, you will come across a CAPTCHA at the end of the sign-up form so as to ensure that the form is filled out only by a legitimate human and not by any of the automated software or a computer bot. The main goal of CAPTCHA is to put forth a test which is simple and straight forward for any human to answer but for a computer, it is almost impossible to solve. What is the Need to Create a Test that Can Tell Computers and Humans Apart? For many the CAPTCHA may seem to be silly and annoying, but in fact it has the ability to protect systems from malicious attacks where people try to game the system. Attackers can make use of automated softwares to generate a huge quantity of requests thereby causing a high load on the target server which would degrade the quality of service of a given system, whether due to abuse or resource expenditure. This can affect millions of legitimate users and their requests. CAPTCHAs can be deployed to protect systems that are vulnerable to email spam, such as the services from Gmail, Yahoo and Hotmail. Who Uses CAPTCHA? CAPTCHAs are mainly used by websites that offer services like online polls and registration forms. For example, Web-based email services like Gmail, Yahoo and Hotmail offer free email accounts for their users. However upon each sign-up process, CAPTCHAs are used to prevent spammers from using a bot to generate hundreds of spam mail accounts. Designing a CAPTCHA System CAPTCHAs are designed on the fact that computers lack the ability that human beings have when it comes to processing visual data. It is more easily possible for humans to look at an image and pick out the patterns than a computer. This is because computers lack the real intelligence that humans have by default. CAPTCHAs are implemented by presenting users with an image which contains distorted or randomly stretched characters which only humans should be able to identify. Sometimes characters are striked out or presented with a noisy background to make it even more harder for computers to figure out the patterns. Most, but not all, CAPTCHAs rely on a visual test. Some Websites implement a totally different CAPTCHA system to tell humans and computers apart. For example, a user is presented with 4 images in which 3 contains picture of animals and one contain a flower. The user is asked to select only those images which contain animals in them. This Turing test can easily be solved by any human, but almost impossible for a computer.  Breaking the CAPTCHA The challenge in breaking the CAPTCHA lies in real hard task of teaching a computer how to process information in a way similar to how humans think. Algorithms with artificial intelligence (AI) will have to be designed in order to make the computer think like humans when it comes to recognizing the patterns in images. However there is no universal algorithm that could pass through and break any CAPTCHA system and hence each CAPTCHA algorithm must have to be tackled individually. It might not work 100 percent of the time, but it can work often enough to be worthwhile to spammers.

Free Softwares

Maxthon 3.0.19.3000 Maxthon Internet Browser software is a powerful tabbed browser with a highly customizable interface. It is based on the Internet Explorer browser engine (your most likely current web browser) which means that what works in the IE browser will work the same in Maxthon tabbed browser but with many additional efficient features:

Realtek High Definition Audio 2.56 Vista The Realtek High Definition Audio codecs are compliant with Microsoft's UAA (Universal Audio Architecture). The top series provide 10 DAC channels that simultaneously support 7.1 sound playback, plus 2 channels of independent stereo sound output (multiple streaming) through the front panel stereo output. Flexible mixing, mute, and fine gain control...

WinRAR 4.00 Beta 4 (32-bit) WinRAR is an archiving utility that completely supports RAR and ZIP archives and is able to unpack CAB, ARJ, LZH, TAR, GZ, ACE, UUE, BZ2, JAR, ISO, 7Z, Z archives. It consistently makes smaller archives than the competition, saving disk space and transmission costs.

AceHTML: Free HTML Editor

AceHTML: Free HTML Editor AceHTML is a popular, free HTML editor that comes loaded with features , which is of great help to the web developer. The complete set of tools for web development combined with intuitive features and professional webmasters enable the web developers to develop robust websites seamlessly. The extensive functionalities and easy to use design makes it one of the best free HTML editor. Also check out free PHP editor, and free CSS editor. Some of the features of AceHTML free HTML editor are:  This free HTML editor supports development in various languages like PHP, PERL, ColdFusion, XML, WML, ASP, CSS and JavaScript. Web development aid to assist the developer. Editing file directly from the server is possible with this free HTML editor. Syntax checker to check the syntax of the HTML script. Coding support and code reuse options available. Code coloration to indicate different HTML tags.  As many as 175 predefined DHTML and JavaScript code templates that can be used by the developer like ‘off- the- shelf’ template. This free HTML editor comes with built-in feature rich style sheet editor for CSS. Viewing server-side pages on the editor is also possible. This is of great use to those who develop pages in ASP and PHP which need virtual servers to run the pages every time. Access to thousands of designs and styles and as many as 40000 graphics templates. Integrated viewer to view the changes that are made, instantly. Full site link-checker to find if the links are not broken. Saving an HTML page as a template to be used some time later is also possible. Code validation to check for errors in a PHP/ ASP code is available. The errors in codes developed in other languages like CSS, JavaScript can also be checked and corrected. Simple, intuitive interface makes this free HTML editor easy to use.  Importing  Rich text Files (RTF) is possible. Uploading files through FTP (File Transfer Protocol ) to the servers is possible. Showing/ Hiding a toolbar, creating custom toolbars, customizing short-cut keys, all can be done in the AceHTML editor. Custom buttons, code explorer, File manager, bookmark management are other such features. Other free HTML editors we reviewed earlier include Kompozer, and PageBreeze. Thus AceHTML is a robust, feature rich HTML editor available. In fact , it is much better than many other paid editors available online. The latest version of AceHTML sizes just about 10 MB. The installer can be downloaded from here. AceHTML freeware editor can be run on various versions of the Windows Operating Systems like  7, Vista, XP, 2000.

BuduIP: Free IP Scanner

BuduIP: Free IP Scanner BuduIP is a free IP scanner that scans all IP addresses in a network, and finds out which IP addresses are used, and which ones are vacant. You just need to provide IP Range that you want to scan, and BuduIP will scan all IP addresses within that range. You can export the generated report to know which IP addresses are vacant. To use this free IP scanner, just provide the IP address range. For example, in the screenshot below, the starting IP address has been provided as 192.168.1. This free IP Scanner then generates all IP addresses that start with 192.168.1, and pings them to see if they exist. If it does not gets response back from some IP address, it classifies it as vacant, and classifies other as Taken. This free IP Scanner is quite useful in large organizations where network administrators want to track which IP addresses have been taken, and which are available. It can even be used for home users to see that no unatuhorized user is connected to their network. Also check out free VPN software. Download BuduIP here.

KooBits: Free ebook Reader Free eBook Downloader

KooBits: Free ebook Reader Free eBook Downloader  Koobits is a popular free ebook reader that lets you download free ebooks, maintain ebook library, and read ebooks on your PC. Koobits ebook reader software allows the user to read, organize, store and manage a large number of e-books in a single place. Thus Koobits free ebook reader not only allows the user to read e-books , but also to organise and archive them. Koobits freeware is an all- in- one solution to read and manage e-books. Other free ebook readers we reviewed earlier include Blio, Lucidor, and Martview. The key features of Koobits E-book reader freeware are: Read Ebooks: With Koobits free ebook reader, the user can read the e-books in various formats.  The intuitive interface loaded with tools and various features makes a great reading experience. The user can read digital books in various formats like PDF, XML, HTML, EPUB, KBJ and even more. Organize Ebooks: Apart from accessing ebooks and reading them, one can also organize and manage them as archives. They can be retrieved and used anytime later by the user. Extract and annotate digital book contents: The user can also extract and annotate favorite portions, quotations, and text from these e-books. The user can personalize the e-books by marking these portions specifically for reference later  or even copy the content to be pasted elsewhere, depending upon need. Access Free E-books: The user can access the book store that is maintained by the vendors of this freeware. The user has to click on the store to access the online collection of e-books. Click add to library to begin downloading the e-book of choice, to the system storage.  Now the user can enjoy reading this book even when offline. The bookstore contains books of various genres like Graphic novels, Fictions, Romance, Science, Art books, biographies, memoirs, business books, cook books , entertainment books etc., Further the user can register with the website and specify e-books of his choice. The e-book is delivered to the dropbox in the account of the user and he can use it for free for one day. Also check out free ebook creators, and free ebook editor. Koobits has been designed to be run on various versions of Windows Operating Systems like XP, Vista, 7. Further Koobits free e-book reader can also be run on Mac Operating System. The latest version of this free ebook reader is just about in  13 MB size and can be downloaded for free from here.