How Would You Design a Captcha for the Deaf-Blind?

kesuki asks: "Right now, the state of the art captcha only works for the visually-abled. Some people are trying to start a grass roots opposition to catcha using existing anti-discrimination laws. However, without any captcha at all, spammers would have a field day. Audio captcha would work for the blind, of course, but they still leave out the deaf-blind using brail interpreters to use their computers and navigate the web. What system of captcha can you dream up that would work for the deaf-blind?"

A math question

[DynaSoar]

All in words, no numerals:
Challenge (example): "seven times three"
Response "twenty one"

self-describing sentences

[Lord Bitman]

There have already been captchas designed which show a semi-randomly created arrangement, and ask the user to solve something based on the image. (I dont remember the example, but someone untrusted in my head is saying "where is the person in relation to the bowl?"). Couldnt be too hard to construct a sentence the way you construct an image. Note that the image doesnt need to make sense, it just needs to have its basic components be recognizeable by a person.

But then someone will complain "By using sentences, you're blocking out all the blind deaf non-native-english-speakers, who can't determine the subtleties of meaning any better than a computer!"
Eventually there has to be a cut-off point.

Yes, I am talking about trying to get a computer to randomly generate riddles.

Easy

[epsalon]

Have a simple form for the deaf-blind. Add a field asking to explain your condition in your own words. The form gets read by real people who may send a follow-up e-mail asking for a reply. You can easily detect if you're talking to a computer. You can make the form only visible to text-based browsers. As this will not work for spamming, few will fill in the form.

Identity system like OpenID as alternate login

[robla]

If there were someone running an OpenID site [openid.net] that had an accessible but spammer-unfriendly login mechanism, that site could serve as an alternative login for visually-impaired users. That admittedly just punts the issue, but the nice thing about that solution is that if there was a trusted site that most blind people would feel comfortable registering with, that site could vet the visually impaired. The OpenID solution wouldn't have to be limited to the blind, but that seems the easiest bootstrapping mechanism, as the blind are probably more motivated to promote/use something like OpenID than people who are perfectly happy with Captcha.

Rob

Re:A math question

[BrynM]

Searching for word names of numbers is almost as easy as solving the math. I have a few standard functions in my code library that translate words to numbers and back in at least three languages. I can bet most other programmers do too. Good idea, but some random mis-spellings of the words would make it better. For example:
Challenge: "sevn t1mes thrree"
Response: "21"
Humans are good at figuring out missspelled words and what they are. I guess someone could use a spell check library, but massaging it to hack might be more trouble than it's worth.

Maybe something that mis-spells words in the first place might work. Say, provide the wrong letters:
Challenge: "Oniad Ptateg" (hint: America )
Response: "NTSS"

How about

[Landak]

"If you cannot view this Captcha, please email [e-mail] [spam assasin'd, of course], or call 0800-1234-567"

Entire avoidance

[irc.goatse.cx troll]

"If you can not see/hear this, please email an admin for assistance".

Then when you get a request, manually assist them assuming they send a nice enough email. Get 500 email requests? mass delete.

Don't forget captchas are to prevent repetitive automated signups, not just a single signup.

Long-winded English, maybe?

[zoeblade]

So, if I understand this right, you need a computer to be able to randomly generate a question and corresponding answer from scratch (pulling it out of a database would presumably just lead to the spammers cataloguing all of the question componenets), but on the other hand, you need a computer to not be able to work out the answer when given just the question.

My best idea is to get it to generate long-winded English sentences along the lines of this:

Please enter any five letters, except that the middle one must be E. Make sure two of the letters are the same.

It would probably be a lot easier to just have a human being read each post and make sure it's not spam before displaying it publicly though, as is the case with moderated newsgroups.

At the rate we're headed, it seems like pretty soon Google will be able to whip up a robot that can beat the Turing test or Voight-Kampff empathy test.

Re:How about...

[Feanturi]

Ok, I'm replying to my own post, whatever.. Anyway here's something you could try to make: That small dot-matrix display, make it much more useful by developing a less expensive way to make tons of these 3d pixels that don't break down often. Work on that. Make a display that could show an actual VGA output at a low-but-acceptable resolution if you could make a good enough array of pins. Colours could be represented by the heights of the pins: a special driver would be involved to assign incoming colours to different elevations and the user would learn to understand them as indications of an image. If they used to have sight they might get a considerably raised internet experience over time. Even born blind too, they'd just have different ideas of what the colours were. In the web browser, everything's there on the tablet like it would be on a normal screen, except the text is in braille, and all images have a well-defined 'box' of fully raised (white?) pixels around them so the user knows right away that they're coming onto an image. They could learn to feel graphics this way. This might open up other avenues to blind users of computers, like better access to games. Some styles of games still wouldn't be suitable for them, but they'd get a hell of a lot more than what they've got now.

And for sighted hardcore game addicts, they could pick up the skill and use the device to finally be able to play in their sleep.