Breaking a Visual Captcha: a Novel Approach Using Hmm
نویسندگان
چکیده
Completely Automated Public Turing Tests to Tell Computers and Humans Apart (CAPTCHAs) are the automatic filters that are widely used these days to disallow any automated script that can perform the work of a human. CAPTCHAs are built in such a way that it is very difficult for any automated script to break them. In this paper, a novel approach for EZ-Gimpy CAPTCHAs has been proposed that first preprocesses the given CAPTCHA, segments its characters, matches the character’s features with the features in a characteristic table and then uses HMM to recognize the characters of the CAPTCHA. Results verify the effectiveness of the approach.
منابع مشابه
SEIMCHA: a new semantic image CAPTCHA using geometric transformations
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...
متن کاملVisual Cryptography Scheme to Predict Phishing Sites
Phishing is an attempt by an individual or a group to thieve personal confidential information such as passwords, credit card information etc from unsuspecting victims for identity theft, financial gain and other fraudulent activities. In this paper we have proposed a new approach named as "A Novel Antiphishing framework based on visual cryptography" to solve the problem of phishing. Here an im...
متن کاملImpeding CAPTCHA Breakers with Visual Decryption
Abuse of free Internet resources and services from false account creation, to spam, to identity theft, excessive bandwidth usage, or even vote stuffing online polls is a big problem. The Completely Automatic Public Turing Test to tell Computers and Humans Apart (CAPTCHA) controls access to resources but automated systems are increasingly adept at overcoming them. In this paper a method of acces...
متن کاملA New Fast and Efficient HMM-Based Face Recognition System Using a 7-State HMM Along With SVD Coefficients
In this paper, a new Hidden Markov Model (HMM)-based face recognition system is proposed. As a novel point despite of five-state HMM used in pervious researches, we used 7-state HMM to cover more details. Indeed we add two new face regions, eyebrows and chin, to the model. As another novel point, we used a small number of quantized Singular Values Decomposition (SVD) coefficients as feature...
متن کاملA Novel Approach to Background Subtraction Using Visual Saliency Map
Generally human vision system searches for salient regions and movements in video scenes to lessen the search space and effort. Using visual saliency map for modelling gives important information for understanding in many applications. In this paper we present a simple method with low computation load using visual saliency map for background subtraction in video stream. The proposed technique i...
متن کامل