A few more thoughts...
I've actually thought of a system which might actually solve this
problem, but it has a few problems of its own. My idea would be to have the
captcha be digits, and to have questions the web visitor must answer in
order to determine those digits. E.G.
Okay, your first digits can be calculated by answering this question. How
many months are in a year? Your next digit is. What's the number of days in
a week? If you have two dozen eggs, what number of eggs do you have? That's
your last set of digits.
In this example, the answer would be 12724. Questions would be asked
deliberately in several different formats in order to confuse voice
recognition systems. There would be many of these questions, each of which
was asked several different ways. To assemble the audio captcha, you'd take
a random subset of these questions.
One problem is that the visitor would have to know good English.
Another issue is that these questions would have to be things which almost
anybody would know. For example, asking for the number of innings in a
baseball game would stump someone who didn't know anything about that sport.
Jayson
----- Original Message -----
From: "Chris Blouch" <[EMAIL PROTECTED]>
To: "General discussions on all topics relating to the use of Mac OS X by
theblind" <[email protected]>
Sent: Thursday, June 19, 2008 2:05 PM
Subject: Re: Please Join Me In Making Craigslist Accessible Again
Exactly. Just like their visual counterparts, audio captchas are
obfuscated to resist cracking by voice recognition. I know one of the guys
who did one of the voices for AOL's captcha and they had to make it
tougher to keep out the hackers. Hence a random mix of letters and numbers
with different voices and background noise. As I mentioned before, it's an
arms race. As the algorithms of the bad guys get better the cognitive load
required to understand the captcha will rise to the point where regular
folks won't be able to pass the test. Turing would be impressed.
While we could switch to some other tests they would have to be
sufficiently complex to fool an algorithm while simple enough that a real
human being can solve them and not necessarily require English as a first
language. I haven't seen another better solution yet. There are some
visual ones with random photos and letters where you have to identify
which one is a cat or whatever, but that's not really accessible.
CB
Jayson Smith wrote:
Some more observations...
On my Windows machine, I acted like I was trying to sign up for a new
account, and it gave me the old-style audio captcha. I went to post, but
don't actually have anything real to post, so didn't go through with it,
so don't know what I'd have gotten.
As for the old audio captcha, assuming it's gone, I'd be surprised if
they go back to it. As I pointed out earlier, the phonetic words they
used are very well known world-wide. I'm sure these very words were
specifically designed so that any one of them can be distinguished from
any other word in that set, E.G. during a radio transmission in less than
optimal signal conditions. Probably pretty easy for a voice recognition
system to crack that.
Jayson
----- Original Message ----- From: "Tiffany D" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, June 18, 2008 6:48 PM
Subject: Please Join Me In Making Craigslist Accessible Again
*Please pass this onto any groups or individuals you think could help.
This is serious.
*
Hello to all,
As most of you know by now, many sites use capcha for making posts
etc. Craigslist was always one of the best in this regard. Their
audio was clear and clean, even employing words for letters (a, as in
alpha) to make understanding the codes easier. However, I just logged
in today and when I tried to make a post, I noticed that it didn't
work at all on my Macbook. When I tried posting with my Windows XP
computer, I discovered that their formatting has changed. Not only is
their an extra step to post, but the audio capcha is now similar to
AOL, with many voices speaking at once and it's very difficult to hear
the actual letters in the capcha. I propose creating a petition, to
be signed by all blind and visually-impaired people, as well as other
concerned parties, asking Craigslist to return the capcha to it's
former state and to once again make it Mac and VoiceOver accessible.
While I was posting an add for my personal use, my job also relies
heavily on Craigslist to generate ads and I'm clearly not the only
blind individual using it for this purpose. Please join me in this
effort. The changes are extremely recent and we may be able to stop
this before it becomes permanent.
Thank you,
Tiffany Dunn
