48 lines
2.5 KiB
TeX
48 lines
2.5 KiB
TeX
\begin{abstract}
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CAPTCHA systems were originally designed to protect against automated
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bot-based Denial of Service (DoS) attacks and spam. But over time, these
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systems have become ineffective due to overfocus on identifying humans from
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bots than combating DoS attacks and spam. As a result, they have become
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privacy invasive systems that pose accessibility challenges with reduced
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effectiveness and accuracy.\ mCaptcha is a proof of work based,
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non-interactive DoS protection system designed to overcome the limitations
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of traditional CAPTCHA systems' limitations while offering superior
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protection services. The mechanism is stateless, so it is able accurately
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defend against attacks over anonymous networks like TOR and the
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non-interactive nature makes it ideal users with auditory, cognitive and
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visual disabilities.
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\end{abstract}
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\section{Introduction}\label{sec:intro}
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Denial of Service (DoS) attacks and spam campaigns reduce the quality of service
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for internet services. Different types of rate-limiters were employed to combat
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such attacks. Today rate-limiters on the web are synonymous with CAPTCHAs.
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CAPTCHA systems work on the premise that an automated bot user can inflict more
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damage than a human user and attacks can be contained if they can accurately
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differentiate a human from a bot. The rise of cheap human labor powered CAPTCHA
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farms in third-world countries have given attackers a way to bypass CAPTCHA
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systems. To combat this new threat, CAPTCHA implementers are constantly raising the
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difficulty of the challenges. This universal raise in difficulty impacts bots
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and unassuming alike. The web is becoming increasingly less accessible to users
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with disabilities and non-English speaking users. Some CAPTCHA systems employ
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multiple methods to in their process. Privacy invasive mechanisms like cookies
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and IP tracking are popular methods that are used in conjunction with
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traditional CAPTCHA mechanisms, both of which are ineffective against
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anonymous networks like TOR and pose serious privacy risks to their users.
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The rest of this paper, rates different CAPTCHA mechanisms and systems based on
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parameters mentioned below and describe how mCaptcha overcomes some of
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them.
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\input{intro/scale.tex}
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% ==================================================
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% Parameters
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% ==================================================
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\input{intro/params.tex}
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% ==================================================
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% Methods
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% ==================================================
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\input{intro/methods.tex}
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