Captchas and security

techie | June 19 - 2010

Captcha is an acronym for “completely automated public Turing test to tell computers and humans apart”. It is a method of differentiating human users from “bots”, software that tries to make use of your website / online tools. Captchas can help protect information and your storage/bandwidth from being eaten up by automated processes. Normal Captchas are text based with small letters capital letters and they are irregular in their positions with various color options. Band width of a website will be eaten up by the automated tools. Using automated tools for SEO practices is called spamming of the search engine.

When people want to monopolize the natural processes and occupy the tools or websites inbuilt applications for a long time continuously it is necessary to prevent them. The script gives an open source implementation of a Captcha. The Captcha covers the following features.

– The text is horizontally and vertically distorted.

– It is easily possible to use your own font and background-color.

– You can configure the behavior of the Captcha.

– Guidelines are added to make segmentation more difficult.

The Captcha has been used successfully in practice. However, a serious check using OCR techniques would be extremely useful.

Captcha is very important as people use automated tools to submit the articles or blogs to multiple websites. Captcha identifies the submission by human and tools. Captchas are widely used by websites for security and privacy purposes. However, traditional text-based Captchas are not suitable for individuals with visual impairments. There are Captchas that have been developed for the users with visual impairments. These have audio and visual information to allow easy access by users with visual impairments.

Captchas are based on the fact that humans tend to be better at image recognition problems than automated systems,  as Google provides both e-mail and blogging services that rely on them for security. So the Google researchers were apparently able to come up with the new technique simply by looking into areas that computer scientists had identified as being problematic for computer-based solutions. Google is providing mail and blogging as service. They apparently came up with image orientation. Humans can apparently properly orient a variety of images so that the vertical axis matches the real-world orientation of the photograph’s subject; computers can only handle a subset of these.