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Complete list of publications and software related to Captcha
Text-based CAPTCHA Strengths and Weaknesses
Based on sucessfull attacks on 13 of the most popular captchas schemes we show how to attack text-based captchas and provide guidelines on how to design secure ones.
@CCS, October 2011
The Failure of Noise-Based Non-Continuous Audio Captchas
We show how using a generic approach, based on advanced audio processing and machine learning algorithm, our captcha breaker "Decaptcha" is able to break all the popular audio CAPTCHA schemes, including Microsoft and Yahoo.
@S&P, May 2011
How Good are Humans at Solving CAPTCHAs A Large Scale Evaluation
We perform a mass-scale user study on how people react to the 21 most popular captcha schemes (13 images, 8 audios). This study reveals that even the most popular captchas scheme are often difficult for humans, with audio captchas being particularly problematic.
@S&P, May 2010
Decaptcha Breaking 75% of eBay Audio CAPTCHAs
This paper shows how Decpatcha is able to break eBay captchas with 75% accuracy. We show that using a custom breaker (75%) greatly out-perform state of art speech recognition system (1%)
@WoOT, August 2009
Easy Does It: More Usable CAPTCHAs
Websites present users with puzzles called CAPTCHAs to curb abuse caused by computer algorithms masquerading as people. While CAPTCHAs are generally effective at stopping abuse, they might impair website usability if they are not properly designed. In this paper we describe how we designed a new CAPTCHA schemes for Google that focus on maximizing usability. Our new scheme which is now an integral part of our production system and is served to millions of users, achieved a 95.3% human accuracy, a 6.7% improvement compared to the old one.
@CHI, April 2014
About me
Lead Google's anti-abuse research. Develop new ways to protect users and disrupt bad guys. Make Chrome safer and faster. Help keeping G+ and Gmail clean. Wear berets. Do magic tricks.
side bar: 0.119889974594
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