Tim O'Reilly

Best Idea for a CAPTCHA ever

by | @timoreilly  | +Tim O'Reilly  | Comments: 4 | 17 July 2006

O'Reilly editor Brian Sawyer just sent a link to Mark Pilgrim's new video blog with the headline: Best Idea for a CAPTCHA ever. Mark wrote: "I need to implement some sort of CAPTCHA based on Strunk & White. If you can’t tell me the difference between 'continual' and 'continuous,' I don’t want to talk to you." OK. Maybe this is mostly for editing wonks.

Comments: 4

Bob Aman [17 July 2006 12:28 PM]

Hehe, apparently I wasn't the only person who heard that and went, "Wait, hold on, that's a good idea!"

Synonymous [17 July 2006 12:56 PM]

I like the idea, but I think this captcha mashup may actually be more effective.

Bob Aman [17 July 2006 05:27 PM]

-dies laughing-

"I met my wife on your captcha!!!"

jake [24 July 2006 10:01 AM]

A good friend of mine who is in the CAPTCHA business writes:

In reality a captcha like this is somewhat bogus because there's a finite number of images available. The people who need solutions are desperate enough to database every single image via an MD5 or SHA1 hash and do a quick lookup later. Unless you can slightly modify each image to throw off the sum without disturbing the 'hotness', even a few hundred thousand images would not be enough.

There was one ticket broker who did something like this to bypass Ticketmaster. He manually matched a word to image and stored 200,000 MD5 sums. This worked because CAPTCHAs are usually pregenerated offline and stored as static images. Generating images on the fly would kill most web servers.

It does have entertainment value, though.

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