CAPTCHA And OCR

Aug 22, 2007

It seeems that captcha is on its way out now that more applications are able to "read" captcha images. Since I like trying to stay a step ahead, what do you think of this concept and do you think it will work.

Just a note, it is not completed at this time as I'm still coding it. You can keep refreshing the page to see the others. This is still strictly a work in progress (WIP).

I have this setup...

* For some, I have 2 rows of numbers/letters. The script will expect only one row to be re-typed.

* Using the 2 rows setup from above, the script could also ask for the letters in column 1 to be re-typed. There are 4 columns.

* Thers also one for where the script will generate a 8 character string, but it will ask for letters with a specified color.

How well do you think this will thwart such applications using OCR capabilities.?

Demo:
[url]

Just a note:
* That site is run out of my house specifically for development purposes so if you access it and get parse errors, or no loads... you know a possible reason why the script will be up and down.

* Remember... It's not done, I'm going to add grid lines around the lettering for the columns and rows and possibly make the text larger.

* Also right now, the colors only return as one color... Soon, each letter will be given a random color.

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Reviews On Best CAPTCHA Scripts And Graphics

Dec 12, 2007

On 10-22-2007, 02:43 PM, "infuseweb" asked:

Quote:

TITLE: Server-side captcha scripts

Does anyone know of any language-neutral captcha scripts that can be run on the server-side and your customers can access via includes or what-not? I'd like to offer some sort of captcha solution to my customers to protect their web forms.

Then, on 10-22-2007, 05:27 PM, "domainworldaccess" replied:

Quote:

bestwebforms.com

Never used it. Heard it is nice. About $30 for up to 50 sites...

(There were no other replies in that thread.)

Are there any readers here who have tried using the paid solution offered by bestwebforms.com? When I visited the site, it seemed that their CAPTCHA graphics files looked a little primitive. Since I have not downloaded their package, I do not know how well it works, or how effective it might be in discouraging web form spamming.

They say that one only needs to insert a short JavaScript on the web page in order to implement their pre-formatted forms. But what if one wishes to apply their CAPTCHA solution to a custom-designed form and lay-out that is already in use (i.e.: currently running without CAPTCHA)?

It would be terrific if any readers could reply with a list of their favorite sources for CAPTCHA scripts, particularly those which can be easily implemented without extensive knowledge of perl or other programming experience.

Assuming one has good HTML and basic script editing capability, which scripts would you suggest? Do they generate the CAPTCHA graphics on-the-fly, or do they depend on a static library of existing .gif files?

Have you tested the script(s) yourself, and arrived at any conclusions on its/their efficacy in combatting web form spam, while still permitting reasonable access by humans with various levels of visual acuity, i.e.: the ability to discern different colors, or contrast between the characters and background?

Since I've read that there may be a number of effective anti-CAPTCHA schemes used by spammers out there (which are able to automatically decode or read the obscured characters with some sort of OCR (Optical Character Recognition) technology, I would like to know whether the whole CAPTCHA approach is now considered to be an exercise in futility.

For example, I noticed that Network Solutions had been using CAPTCHA for a time on their WHOIS search page, but later abandoned it. I'm assuming they may have concluded that it was hindering more valid users from performing searches, than it was effective in stopping spam submissions.

A while back, I did read some forum posts which suggested wrapping the form action in JavaScript, in order to foil certain automated spambots. However, after implementing that solution, I have not found it to be entirely effective. Of course, I have no way of knowing whether the comment spam that we continue to get now was generated by a human or a spambot.

Finally, it seems that our web host's Spam Assassin software, while it is pretty decent at detecting spam in regular e-mail, does nothing to filter spam in web forms whose input is delivered by e-mail. I don't understand why this is, since it still must pass through the mail server in order to be delivered to me.

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