Posted by Stuart Millington on 04/30/07 23:29

On Mon, 30 Apr 2007 15:57:54 -0700, zach <wackzingo@gmail.com> wrote:

>type. At least for me this seemed faster and easier. I get confused with
>some captcha's because I can't tell if a letter is an l or i or o and 0.

Indeed, in many image based schemes it's hard for sighted, let alone
partially sighted, people to see the difference between a zero and an
"oh".

>Just a thought on speed and usability. Is there a security reason why
>using only numbers shouldn't be used?

In terms of usability, image-only schemes should never be used (in the
UK at least), as they discriminate in violation of the DDA 1995 unless
adequate, alternative, provision is made.

IME the number of sites using these techniques who bother to implement
such alternatives are close to zero :-(

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