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USS
2010
8 years 5 months ago
Re: CAPTCHAs-Understanding CAPTCHA-Solving Services in an Economic Context
Reverse Turing tests, or CAPTCHAs, have become an ubiquitous defense used to protect open Web resources from being exploited at scale. An effective CAPTCHA resists existing mechan...
Marti Motoyama, Kirill Levchenko, Chris Kanich, Da...
SICHERHEIT
2010
8 years 5 months ago
CAPTCHAs: The Good, the Bad, and the Ugly
A CAPTCHA is a program that generates challenges that are easy to solve for humans but difficult to solve for computers. The most common CAPTCHAs today are text-based ones where a ...
Paul Baecher, Marc Fischlin, Lior Gordon, Robert L...
CMS
2006
170views Communications» more  CMS 2006»
8 years 8 months ago
Enhanced CAPTCHAs: Using Animation to Tell Humans and Computers Apart
Abstract. Completely Automated Public Turing Test to tell Computers and Humans Apart (CAPTCHA) is a
Elias Athanasopoulos, Spyros Antonatos
NIPS
2008
8 years 8 months ago
Breaking Audio CAPTCHAs
CAPTCHAs are computer-generated tests that humans can pass but current computer systems cannot. CAPTCHAs provide a method for automatically distinguishing a human from a computer ...
Jennifer Tam, Jirí Simsa, Sean Hyde, Luis v...
SP
2010
IEEE
192views Security Privacy» more  SP 2010»
8 years 11 months ago
How Good Are Humans at Solving CAPTCHAs? A Large Scale Evaluation
—Captchas are designed to be easy for humans but hard for machines. However, most recent research has focused only on making them hard for machines. In this paper, we present wha...
Elie Bursztein, Steven Bethard, Celine Fabry, John...
EUROCRYPT
2003
Springer
9 years 13 days ago
CAPTCHA: Using Hard AI Problems for Security
We introduce captcha, an automated test that humans can pass, but current computer programs can’t pass: any program that has high success over a captcha can be used to solve an u...
Luis von Ahn, Manuel Blum, Nicholas J. Hopper, Joh...
ISW
2004
Springer
9 years 17 days ago
Image Recognition CAPTCHAs
CAPTCHAs are tests that distinguish humans from software robots in an online environment [3, 14, 7]. We propose and implement three CAPTCHAs based on naming images, distinguishing ...
Monica Chew, J. D. Tygar
HIP
2005
Springer
174views Cryptology» more  HIP 2005»
9 years 22 days ago
Collaborative Filtering CAPTCHAs
Abstract. Current CAPTCHAs require users to solve objective questions such as text recognition or image recognition. We propose a class of CAPTCHAs based on collaborative filterin...
Monica Chew, J. D. Tygar
WMCSA
2008
IEEE
9 years 1 months ago
Making CAPTCHAs clickable
We show how to convert regular keyboard-entry CAPTCHAs into clickable CAPTCHAs. The goal of this conversion is to simplify and speed-up the entry of the CAPTCHA solution, to minim...
Richard Chow, Philippe Golle, Markus Jakobsson, Lu...
WCRE
2008
IEEE
9 years 1 months ago
Reverse Engineering CAPTCHAs
CAPTCHAs are automated Turing tests used to determine if the end-user is human and not an automated program. Users are asked to read and answer Visual CAPTCHAs, which often appear...
Abram Hindle, Michael W. Godfrey, Richard C. Holt
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