JaninaSajka
commented
5 years ago Thank you, Russell. We've added a Proof of Work section here:
https://w3c.github.io/apa/captcha/#proof-of-work-techniques
Please let us know if you think we missed anything, or if you think we've not fully captured the relevance for CAPTCHA.
Best,
Janina
Russell Smith writes:
This is missing proof of work based solutions - these slow down spammers by changing the amount of work they can do in a given time, making a site using them less profitable per attack.
Upsides; non-interactive, will always work eventually with JS enabled, no obvious human language issue or accessibility issues. Downsides; takes longer on slower computers (phones, older machines), doesn't actually stop spam - just makes it less profitable per unit of compute
Examples:
- https://github.com/xenohunter/lapti-pow-captcha
- https://github.com/trikota/flask_hashcash
- http://www.hashcash.org/
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Janina Sajka
Linux Foundation Fellow Executive Chair, Accessibility Workgroup: http://a11y.org
The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI) Chair, Accessible Platform Architectures http://www.w3.org/wai/apa
This is missing proof of work based solutions - these slow down spammers by changing the amount of work they can do in a given time, making a site using them less profitable per attack.
Upsides; non-interactive, will always work eventually with JS enabled, no obvious human language issue or accessibility issues. Downsides; takes longer on slower computers (phones, older machines), doesn't actually stop spam - just makes it less profitable per unit of compute
Examples: