jquery - How does Google's "No CAPTCHA reCAPTCHA" work? -


i trying build recaptcha-like jquery plugin. far, have completed visual aspect.

any idea how works under hood can replicate same in plugin?

where begin...

  • google has lot of knowledge many browsers , ip addresses google search, google analytics, google adsense can use influence decision whether or not bot or legit browser history
  • they use javascript track mouse movements , keyboard input on page , use complex algorithms server side analyze them decide if bot
  • they use javascript @ various properties of browser (e.g. screen & viewport resolution, plugins, fonts , use complex server side algorithms decide if bot
  • they use vast troves of data see if ip has been challenged many times recaptcha in recent time or historically (signs of bot, normal user might encounter few challenges day, not many hundreds or thousands)
  • i think try use client side javascript inject plugins or other code page , analyze server side test if javascript run (could signal bot if code never runs)
  • probably bunch of other stuff don't know because if did "bad guys" use defeat recaptcha

then if determine bot or can't decide, show normal alphanumeric or image captcha.

keep in mind, if captcha 100% client side jquery/javascript, can , bypassed. need server side processing (php, .net, jsp etc).


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