Linearized computations - was OCR

[Riad S. Wahby]

Declan McCullagh <declan at well.com> wrote:
> I had thoughts along a similar line as Peter's, except to use numbers.
> Include with <img> tags some .GIFs and ask the person/bot to type in
> the numbers in the GIFs. Generate the filenames randomly and expire
> them after five minutes. Should take you 10 minutes to write a
> prototype CGI script in Perl.

This is done somewhere already.  I can't quite remember where, but I
suspect that it's in the EBay registration process.

"For security purposes, retype the numbers to the left."

The numbers aren't vertically aligned, have erratic horizontal
spacing, and are presented against a grid-pattern background.  I'm not
sure if this actually helps much against standard OCR, although I'm
pretty sure that the SVMs I work with could be easily trained to
translate the GIFs to text.

--
Riad Wahby
rsw at mit.edu
MIT VI-2/A 2002