captcha idea: proposal for gnome outreach for women 14

classic Classic list List threaded Threaded
8 messages Options
Reply | Threaded
Open this post in threaded view
|

captcha idea: proposal for gnome outreach for women 14

Mansi Gokhale
hello,

These are some approaches i can think of instead of a text based captcha.

The image idea where users are asked to spot the odd one out like
demonstrated or find all the similar images like mentioned in
here<https://www.mediawiki.org/wiki/CAPTCHA>
.

Also a picture with a part chipped in could be shown and chipped pictures
could be given as options

like find the missing part from a jigsaw puzzle.

The image which would be shown is http://imgur.com/uefeb08

http://imgur.com/KEJqCg3 is the picture which would be the correct option.

The other options could be rotated versions of this , which would not be so
easy for the bot to match. (unless it somehow worked some digital
processing algorithm and matched the color gradients or something like
that).

This is a good option for people who do not know english or are illiterate
and maybe would not understand questions like : is this a bird , plane ,
superman? after being shown a picture.

Tell me what you think

(Sorry to upload those images on imgur. i dont know how to put them on the
wiki .Hope that is ok)


have posted this on the CAPTCHA
page<https://www.mediawiki.org/wiki/Talk:CAPTCHA>also
_______________________________________________
Wikitech-l mailing list
[hidden email]
https://lists.wikimedia.org/mailman/listinfo/wikitech-l
Reply | Threaded
Open this post in threaded view
|

Re: captcha idea: proposal for gnome outreach for women 14

Arthur Richards-2
I think this is an intriguing approach - particularly for use cases on
mobile devices. We display captchas as necessary through MobileFrontend
when they are triggered, but the mobile experience is horrible (arguably
the whole captcha experience is horrible regardless of the medium, but
that's another conversation). As long as we need to surface captchas,
something non-text based, especially if it didn't require typing, would be
preferable.


On Fri, Feb 28, 2014 at 10:07 AM, Mansi Gokhale <[hidden email]>wrote:

> hello,
>
> These are some approaches i can think of instead of a text based captcha.
>
> The image idea where users are asked to spot the odd one out like
> demonstrated or find all the similar images like mentioned in
> here<https://www.mediawiki.org/wiki/CAPTCHA>
> .
>
> Also a picture with a part chipped in could be shown and chipped pictures
> could be given as options
>
> like find the missing part from a jigsaw puzzle.
>
> The image which would be shown is http://imgur.com/uefeb08
>
> http://imgur.com/KEJqCg3 is the picture which would be the correct option.
>
> The other options could be rotated versions of this , which would not be so
> easy for the bot to match. (unless it somehow worked some digital
> processing algorithm and matched the color gradients or something like
> that).
>
> This is a good option for people who do not know english or are illiterate
> and maybe would not understand questions like : is this a bird , plane ,
> superman? after being shown a picture.
>
> Tell me what you think
>
> (Sorry to upload those images on imgur. i dont know how to put them on the
> wiki .Hope that is ok)
>
>
> have posted this on the CAPTCHA
> page<https://www.mediawiki.org/wiki/Talk:CAPTCHA>also
> _______________________________________________
> Wikitech-l mailing list
> [hidden email]
> https://lists.wikimedia.org/mailman/listinfo/wikitech-l




--
Arthur Richards
Software Engineer, Mobile
[[User:Awjrichards]]
IRC: awjr
+1-415-839-6885 x6687
_______________________________________________
Wikitech-l mailing list
[hidden email]
https://lists.wikimedia.org/mailman/listinfo/wikitech-l
Reply | Threaded
Open this post in threaded view
|

Re: captcha idea: proposal for gnome outreach for women 14

Brad Jorsch (Anomie)
In reply to this post by Mansi Gokhale
On Fri, Feb 28, 2014 at 12:07 PM, Mansi Gokhale <[hidden email]>wrote:

> The image idea where users are asked to spot the odd one out like
> demonstrated or find all the similar images like mentioned in
> here<https://www.mediawiki.org/wiki/CAPTCHA>
>

If you display 8 images and the user has to pick one, then even by random
guessing the attacker has a 12.5% chance of passing the captcha. That's not
good at all. Finding "all matching" is slightly better since it reduces the
guessability (1/256 for 8 images), but still not very good. A traditional
captcha using only A-Z is 1/308915776. To do as well with image picking,
you'd need to ask the user to choose the matches from a set of about 28.
Adding in numbers 2-9 is 1/1544804416, needing a set of about 31 images.

The set of possible images also needs to be very large and the
categorization private.
https://www.mediawiki.org/wiki/Talk:Requests_for_comment/CAPTCHA#Issue:_image_classification_CAPTCHAs_need_a_secret_corpusgoes
into much more detail on this issue.

Then there's the issue of different interpretation. Take for example
https://www.mediawiki.org/wiki/File:Find-all-captcha-idea.png. Is the
second image wearing glasses? Or is that a lorgnette or something like
opera glasses, both of which are held in front of the eyes rather than worn?

https://www.mediawiki.org/wiki/File:Find-the-different-captcha-idea.png has
a similar problem. The first image is the only one with a cigarette, and
the only one with non-realistic coloring. The second is the only bald one,
and the only one with something resembling a lorgnette, and the only one
not looking in the general direction of the camera, and the only one with a
book. The fourth is the only child. The sixth is the only obvious female
(I'm not sure about the cat). The eighth is the only one smiling, and the
only one with visible teeth.

Also a picture with a part chipped in could be shown and chipped pictures
> could be given as options like find the missing part from a jigsaw puzzle.
>

> The image which would be shown is http://imgur.com/uefeb08
>
> http://imgur.com/KEJqCg3 is the picture which would be the correct option.
>
> The other options could be rotated versions of this , which would not be
> so easy for the bot to match. (unless it somehow worked some digital
> processing algorithm and matched the color gradients or something like
> that).
>

That seems very simple for a computer to solve. Just find the option with
minimal difference along the join edges, which is probably easier than what
they already do for OCRing text captchas.


As far as captchas, I still think https://xkcd.com/810/ is the way to go.


--
Brad Jorsch (Anomie)
Software Engineer
Wikimedia Foundation
_______________________________________________
Wikitech-l mailing list
[hidden email]
https://lists.wikimedia.org/mailman/listinfo/wikitech-l
Reply | Threaded
Open this post in threaded view
|

Re: captcha idea: proposal for gnome outreach for women 14

Brad Jorsch (Anomie)
On Fri, Feb 28, 2014 at 1:29 PM, Brad Jorsch (Anomie) <[hidden email]
> wrote:

> A traditional captcha using only A-Z is 1/308915776.
>

That should be "a traditional *6 letter* captcha using only A-Z".

Sorry for the noise.

--
Brad Jorsch (Anomie)
Software Engineer
Wikimedia Foundation
_______________________________________________
Wikitech-l mailing list
[hidden email]
https://lists.wikimedia.org/mailman/listinfo/wikitech-l
Reply | Threaded
Open this post in threaded view
|

Re: captcha idea: proposal for gnome outreach for women 14

Matthew Flaschen-2
In reply to this post by Mansi Gokhale
I'm adding the design list.  I talked about this recently with a couple
of the designers.

Matt Flaschen

On 02/28/2014 12:07 PM, Mansi Gokhale wrote:

> hello,
>
> These are some approaches i can think of instead of a text based captcha.
>
> The image idea where users are asked to spot the odd one out like
> demonstrated or find all the similar images like mentioned in
> here<https://www.mediawiki.org/wiki/CAPTCHA>
> .
>
> Also a picture with a part chipped in could be shown and chipped pictures
> could be given as options
>
> like find the missing part from a jigsaw puzzle.
>
> The image which would be shown is http://imgur.com/uefeb08
>
> http://imgur.com/KEJqCg3 is the picture which would be the correct option.
>
> The other options could be rotated versions of this , which would not be so
> easy for the bot to match. (unless it somehow worked some digital
> processing algorithm and matched the color gradients or something like
> that).
>
> This is a good option for people who do not know english or are illiterate
> and maybe would not understand questions like : is this a bird , plane ,
> superman? after being shown a picture.
>
> Tell me what you think
>
> (Sorry to upload those images on imgur. i dont know how to put them on the
> wiki .Hope that is ok)
>
>
> have posted this on the CAPTCHA
> page<https://www.mediawiki.org/wiki/Talk:CAPTCHA>also
> _______________________________________________
> Wikitech-l mailing list
> [hidden email]
> https://lists.wikimedia.org/mailman/listinfo/wikitech-l
>


_______________________________________________
Wikitech-l mailing list
[hidden email]
https://lists.wikimedia.org/mailman/listinfo/wikitech-l
Reply | Threaded
Open this post in threaded view
|

Re: captcha idea: proposal for gnome outreach for women 14

Happy Melon-2
In reply to this post by Brad Jorsch (Anomie)
On 28 February 2014 18:29, Brad Jorsch (Anomie) <[hidden email]>wrote:

> On Fri, Feb 28, 2014 at 12:07 PM, Mansi Gokhale <[hidden email]
> >wrote:
>
>
> Then there's the issue of different interpretation. Take for example
> https://www.mediawiki.org/wiki/File:Find-all-captcha-idea.png. Is the
> second image wearing glasses? Or is that a lorgnette or something like
> opera glasses, both of which are held in front of the eyes rather than
> worn?
>
> https://www.mediawiki.org/wiki/File:Find-the-different-captcha-idea.pnghas
> a similar problem. The first image is the only one with a cigarette, and
> the only one with non-realistic coloring. The second is the only bald one,
> and the only one with something resembling a lorgnette, and the only one
> not looking in the general direction of the camera, and the only one with a
> book. The fourth is the only child. The sixth is the only obvious female
> (I'm not sure about the cat). The eighth is the only one smiling, and the
> only one with visible teeth.
>

I think this is oversimplifying.  Of course some people can interpret a
picture puzzle in slightly different ways - the whole *point* of a captcha
is to distinguish between the intuitive reasoning of a human and the
formulaic reasoning of a computer; if there was absolutely no ambiguity, it
would be a very poor captcha.  In exactly the same way that the letters on
a captcha will sometimes be distorted in such a way that humans genuinely
make a mistake, sometimes the questions in a picture puzzle can be
sufficiently distorted to the point that they are answered incorrectly.
The 'difficulty' of *any* captcha obviously needs to be carefully
calibrated to hit the sweet spot between mundanity and ambiguity.  But
putting out nine pictures of humans and one picture of a cat and asking for
the "odd one out" is no easier to misinterpret than a squiggle that might
be a G or might be a 6.

--HM
_______________________________________________
Wikitech-l mailing list
[hidden email]
https://lists.wikimedia.org/mailman/listinfo/wikitech-l
Reply | Threaded
Open this post in threaded view
|

Re: captcha idea: proposal for gnome outreach for women 14

Steven Walling
In reply to this post by Brad Jorsch (Anomie)
On Fri, Feb 28, 2014 at 6:29 PM, Brad Jorsch (Anomie) <[hidden email]
> wrote:

> If you display 8 images and the user has to pick one, then even by random
> guessing the attacker has a 12.5% chance of passing the captcha. That's not
> good at all. Finding "all matching" is slightly better since it reduces the
> guessability (1/256 for 8 images), but still not very good. A traditional
> captcha using only A-Z is 1/308915776. To do as well with image picking,
> you'd need to ask the user to choose the matches from a set of about 28.
> Adding in numbers 2-9 is 1/1544804416, needing a set of about 31 images.
>
> The set of possible images also needs to be very large and the
> categorization private.
>
> https://www.mediawiki.org/wiki/Talk:Requests_for_comment/CAPTCHA#Issue:_image_classification_CAPTCHAs_need_a_secret_corpusgoes
> into much more detail on this issue.
>

A recent example that springs to mind with image-based CAPTCHAs (instead of
text) is Snapchat's "Find the Ghost", which is very fun for users and
apparently was broken very quickly.[1] A lot of times I hear people also
suggest we try a honeypot on login/signup instead of text-based CAPTCHAs,
and like the Snapchat example, one of the weaknesses here is just not
accounting for that fact that people will target popular sites/apps
directly. They'll inspect the DOM to find honeypots, they'll notice you use
the same logo shape and use computer vision to find that shape, etc.

However, it is not overstating it to say that the text-based CAPTCHA we use
now is the single most frustrating part of creating an account or logging
in (if you misremember your password, which users do all the time). To
quote one of our usability tests during the last login/signup redesign:
"This is ridiculous. I can't even see this.".[2]

One simpler thing we might try and do right now is regenerate our current
pool of CAPTCHAs to make them a bit less hard to read. We've done this kind
of tweaking before without too much trouble I think?[3]

1. techcrunch.com/2014/01/21/snaptcha/
2.
https://www.mediawiki.org/wiki/Account_creation_user_experience/User_testing
3. See bug 43546 which Aaron Schulz kindly took care of. He may be able to
elaborate more.
_______________________________________________
Wikitech-l mailing list
[hidden email]
https://lists.wikimedia.org/mailman/listinfo/wikitech-l
Reply | Threaded
Open this post in threaded view
|

Re: captcha idea: proposal for gnome outreach for women 14

Brad Jorsch (Anomie)
In reply to this post by Happy Melon-2
On Mon, Mar 3, 2014 at 6:05 AM, Happy Melon <[hidden email]>wrote:

> But
> putting out nine pictures of humans and one picture of a cat and asking for
> the "odd one out" is no easier to misinterpret than a squiggle that might
> be a G or might be a 6.
>

It seems to me that putting nine pictures of humans and one picture of a
cat is probably not much harder of a computer vision task than trying to
determine which letter a particular squiggle corresponds to, either. (And
that's leaving aside the fact that an 10% success rate for random guessing
seems pretty bad for a captcha.)

So naturally I thought that the real captchas would have a subtler level of
intended oddness, so that the possibility for unintended oddness to confuse
people would be greater.


--
Brad Jorsch (Anomie)
Software Engineer
Wikimedia Foundation
_______________________________________________
Wikitech-l mailing list
[hidden email]
https://lists.wikimedia.org/mailman/listinfo/wikitech-l