Completely Automated Public Turing test to tell Computers and Humans Apart used in form validation to restrict access to humans only
Questions tagged [captcha]
127 questions
29
votes
3 answers
Is there anything insecure about Google ReCaptcha?
In this question on software recommendations, the OP asks for an alternative to Google reCAPTCHA because "for a security reasons also we don't want to depend on any out side services".
As far as I know, you ask Google for a CAPTCHA, you display it,…

Mawg says reinstate Monica
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If we know CAPTCHA can be beat, why are we still using them?
If we know CAPTCHA can be beat, why are we still using them?
A 35% to 90% success rate like wikipedia is stating means software is better at solving CAPTCHAs then I am.

sup
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13
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AntiForgeryToken versus Captcha
I am having some question regarding captcha and AntiForgeryToken
Do I need to use captcha if I am using AntiForgeryToken in an MVC application.
Does AntiForgeryToken prevents automated form submission?
Can I use AntiForgeryToken as an alternative…

Twix
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9
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5 answers
What type of captcha will you recommend?
What type of captcha will you recommend? I am looking mainly at usability, ease of use (development too), relatively secure
Usability
I find that those captcha with very curly words/numbers are sometimes too unreadable. What I start to see in many…
jiewmeng
5
votes
5 answers
Why re-verify with CAPTCHA on failed form entry?
Is there a reason for sites to ask for another CAPTCHA verification when some other part of the registration form, e.g. the username, was invalid?
user1633
4
votes
2 answers
Are photo recognition captchas a reliable way to distinguish humans from bots?
You all know captchas that require you to either type some letters displayed in an obfuscated way as image.
Recently I started to see more and more captchas that show you a set of small photos and require you to e.g. "select all street signs" or…

Byte Commander
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Are captchas based on ASCII art secure enough?
I have just came across an ASCII art captcha, something that I have never seen before. It seems to be really easy to implement server side!
Are ASCII art captchas secure enough?

Renato Gama
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Anyone using Asirra in production? Are there similar alternatives?
The Asirra project is a Captcha alternative that shows you pictures of kittens and puppies to fend off bots and prove that the end user is a human.
Is anyone using Asirra (or something similar) in production? What alternatives are you aware…

makerofthings7
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3
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A potential CAPTCHA phishing attack against reCAPTCHA?
In reCAPTCHA's API (without plugin), the key part is
3
votes
2 answers
Do we use different CAPTCHAs with different difficulty to how sensitive the request is?
My idea is to use a sort of layered CAPTCHA model (4 layers - from which layer 0 is no captcha) with difficulty as primary focus.
My first focus beside stopping bots is to make the visitor more and more aware of what he's doing.
It will give the…

CriticalSYS
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What is a good way of preventing captcha jacking attacks?
Captcha jacking is an attack to bypass a captcha by coercing a human into solving the challenge response. Prof of concept code that uses a proxy can be found here.
Is there a good method of preventing this type of attack? How can an application…

rook
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How can google's ReCaptcha verify identity *and* train AI?
I have heard that the reason the image portion of ReCaptcha contains so many driving questions is that Google is using it to train AI for their self-driving cars. But to make it an effective security measure, wouldn't Google need to verify that the…

CompileYourCake
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Can we use reverse image search to bypass image CAPTCHAs?
Has there been any group that managed to bypass the Image CAPTCHAs using reverse image search? Whats stopping people from writing a script that bypasses these CAPTCHAs by reverse image searching via many services like Google and make a choice?
And…

Richard Jones
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Is captcha on nth login attempt is really stops bots?
I have a requirement to show google reCaptcha on 2nd attempt on login screen.
But frankly speaking I consider it not the way to stop bots.
Because on server side I cannot tell whether this is the first or second login attempt unless the user…

Muhammad Hewedy
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What is the future of CAPTCHA?
According to this article this guy has made a simple AI to beat CAPTCHA. With the development of AI, robots will pass the Turing test, and bots will beat Google's reCAPTCHA, maybe already there are robots that can beat all captchas, so, what will…

lasan
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