A Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) is designed to distinguish humans from machines. Most of the existing tests require reading distorted text embedded in a background image. However, many existing CAPTCHAs are either too difficult for humans due to excessive distortions or are trivial for automated algorithms to solve. These CAPTCHAs also suff...

Recent document image understanding R&D intended to protect Internet services against abuse by programs is summarized. The accelerating pace of introduction of working CAPTCHAs — completely automatic public Turing tests to tell computers and humans apart — is reported, and the ability of these CAPTCHAs to resist attack is critiqued. Attacks on PARC’s ‘BaffleText’ CAPTCHA by the DIA, CV, and sec...

In this paper, we have proposed a system to grade CAPTCHA strength, according to various parameters determined by breaking the CAPTCHA. There are basically four major steps involved in the system.First step is preprocessing which includes – binarization and noise removal.Second step is segmenting the image into individual characters. Third step is to obtain skeletons of characters i.e., Thinnin...

As protection of web applications are getting more and more important every day, CAPTCHAs are facing booming attention both by users and designers. Nowadays, it is well accepted that using visual concepts enhance security and usability of CAPTCHAs. There exist few major different ideas for designing image CAPTCHAs. Some methods apply a set of modifications such as rotations to the original imag...

A Completely Automated Public Turing test to tell Computer and Humans Apart (CAPTCHA) is a variation of the Turing test, in which a challenge is used to distinguish humans from computers (‘bots’) on the internet. They are commonly used to prevent the abuse of online services; for example, malicious users have written automated programs that signup for thousands of free email accounts and send S...

The Most of the protected resources are based on difficult math issues. How to use hard Artificial Intelligence issues for protection is growing as an exciting new paradigm, but has been under-explored. We apply a new protection resource are based on hard personal Artificial Intelligence issues. CARP also provides a new technique to address the famous image hotspot issue in popular graphical pa...

The research presented in this thesis aims to extend the capabilities of human interaction proofs in order to improve security in web applications and services. The research focuses on developing a more robust and efficient Completely Automated Public Turing test to tell Computers and Human Apart (CAPTCHA) to increase the gap between human recognition and machine recognition. Two main novel app...