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Questions tagged [captcha]

CAPTCHA is a program that protects websites against bots by generating and grading tests that humans can pass but current computer programs cannot.

0
votes
1answer
223 views

JS Captcha in contact form validation to avoid spam bots

I am looking for opinions about how bulletproof could be this captcha system to avoid spam in a contact form. The form submit goes through ajax. So I generate 2 random numbers with javascript. The ...
1
vote
2answers
371 views

How is it possible that facial recognition software can work, but a reCAPTCHA can't be solved by a computer

If software can be built to recognize faces and match those faces to names, then how is that CAPTCHA works? Recognizing letters seems a lot easier than matching faces.
84
votes
7answers
45k views

How can robots beat CAPTCHAs?

I have a website e-mail form. I use a custom CAPTCHA to prevent spam from robots. Despite this, I still get spam. Why? How do robots beat the CAPTCHA? Do they use some kind of advanced OCR or just ...
6
votes
3answers
2k views

Best practices to avoid fake profiles?

When offering to create a profile (for example, login+pwd) for a web service, what are the best practices one should implement to avoid mass spamming/creation of fake profiles? I am thinking about ...
2
votes
2answers
2k views

Are sessions secure for captcha on failed login?

I don't like writing open-ended questions but I have a quick security question. I have a PHP login script that shows a CAPTCHA on the third failed login attempts. The way I'm counting failed logins is ...
3
votes
4answers
310 views

Idea for CAPTCHA

CAPTCHAs have a lot of downsides, accessibility and user friendliness are two things that are often sacrificed. I've thought of an idea that might work really well, has this ever been attempted ...
8
votes
9answers
877 views

A new CAPTCHA using sentences?

I was just thinking about how recaptcha is getting harder when I thought about another posible solution. Images won't last forever so we will need something else some day - like human logic or emotion....
1
vote
1answer
88 views

How can a CAPTCHA be integrated into a community?

I'm planning on making a simple discussion feature for a web framework I'm building. It should: allow anonymous posting block spam bots The obvious answer is to use a generic "captcha" plugin, ...
16
votes
8answers
910 views

Are captchas worth the decreased usability?

When is it useful to use a captcha? When is it an unnecessary hindrance? Is a captcha just a quick fix for the lazy/unexperienced programmer, or are they really the best way to prevent spam and bots?