Hi, all

When you ask for a captcha, I'd first ask what do you want to use it for.
If you read the first lines of Wikipedia it has been developed to differ
between a real user and a bot.

If you'd now say that you want to use it to protect spam in a formula I'd
give you the same explanation that you can find here in german (in a bit
more text): http://www.1ngo.de/web/captcha-spam.html
The author of this link says that captchas are not efficient enough and
give a new unnecessary barrier to all users. He also declaims that bots
nowadays are better than ever and can even read captchas that many humans
are not able to read.
For this reason he provides a list of extra stuff that you can use to
protect your formula against spam instead of a picture that's text should
be written in an input-field.

One of those is the honey-pot. You simply create an additional field (f.e. *
email2*) hide it for most visitors (using *css*) and ignore the comment if
there's text in here. As most of the bots cannot read css they'll fill a
valid email-address in here :) But then you also have to think about users
that have css disabled f.e. *ScreenReader*. Another disadvantage of this
issue is that you can use an auto-field-fill mechanism provided by the
browser who could fill this field ... But both cases should not be that
difficult. For the screenreder you can change the label for the field to
look like *Do not paste your email in here. Just leave it empty.* Just to
have the word email again in here ;)

Another good thing is to think about how fast this form can be submitted
when the user enters the formula for the first time. Also think about the
second time, when the user as entered some wrong values and you have to
show him a message.
If you have a formula that contains more than 5 fields it's quite unusual
that the user can submit that below 2 sec after receiving the response. You
could even add a feature by using javascript that the user cannot submit
this form or his request will be delayed for a view seconds (one or two).

If you want to know more about that, out there are plenty of plugins for
different systems where you can see what other possibilities you have. One
extension i like is the one from TYPO3. They have quite a bunch of such
things and you can give each of the checks a value. If the sum of the
values of the failing tests reaches a configured level, this
form-submission will be rejected.

Wordpress: http://antispambee.de/


2012/2/17 Savetheinternet <savetheinter...@tinyboard.org>

> On Fri, Feb 17, 2012 at 3:40 PM, Donovan Brooke <li...@euca.us> wrote:
> > Hello,
> >
> > Does anyone know of a basic (open source or freeware) form captcha system
> > for PHP?
> >
> > TIA,
> > Donovan
> >
> >
> >
> >
> > --
> > D Brooke
> >
> Hi,
> There are plenty of free PHP captcha scripts out there. Just google
> "captcha PHP". Securimage (phpcaptcha.org) looks relatively okay.
> Thanks,
> Michael
> --
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