"are you human" plugin for rails? does one exist?

Hi all,

Does anyone know if there is a “are you human” plugin for rails that exists? (i.e. where one has to typically read numbers off an image and type them in to avoid spamming).

Perhaps if there is no plugin an open source project that might have one implemented within it that one could use?

Tks

You're looking for captcha. I believe there's a gem and a plugin.
There's also some javascript solutions.