Simple php captcha concept...would this be effective.

[DamienRoche]

I have an idea for a captcha. About 2 years ago I read that humans can read a word, and entire paragraphs with all the letters mixed up - as long as the first and last letter of each word remained in the same place.

 

like:

 

tloltay

 

So...why not put this into a captcha. Feed it a list of 6-10 letter words from a text file, mix the middle parts of the words up and present it on the page.

 

How hard would it be for a bot to crack something like that? I imagine it would have to run through a range of possible words, probably check for an anagram first.

 

My first logic to decipher this is:

 

-check for anagram (if 1 anagram -> cracked!)

else

-put first and last letter into var (if only 1 word can be obtained from mixed letters -> cracked!)

 

So I guess it entirely depends on the ambiguity of the words. One idea I had was to feed it famous phrases and quotes...

 

I'd like some constructive input on this. I feel it's fairly weak, but what would YOU do to make it secure...can you make it secure?

 

Thanks.

 

[corbin]

Hrmmm wow, I actually kind like that idea.

 

 

It would have to be sufficiently long that a bot couldn't just sit there and unscramble the word.  Hrmmmm....  I'm wondering now just how hard it would be to unscramble a word.

 

 

For example, tloltay wouldn't be hard at all to descramble.  Just find words that have only those letters in them, which would probably turn up just "totally."

 

 

 

I see two problems though:

 

1.  Readability.  Can all people read stuff like that, or just most?  (Or even like 50%?)

2.  Some people might get confused.  CAPTCHAs have become standard now, and some people might be like "What the heck is that?  I guess I just put the letters in?"  So you would of course have to explain it on the page.  (Not really a problem, just a concern.)

 

I guess you addressed #1 with the famous quotes thing, even though that assumes that the average user will actually recognize a famous quote.

 

 

 

It would be interesting to see how hard it would be to crack it.  Unfortunately, with a decent word list handy, I don't think it would be hard for a program to crack it .

 

 

I might find a word list later and see how hard it is to crack something like this.  (I would imagine not hard at all.)

[Mchl]

OK... I decrypted it as "today"... I think I failed...

[Flames]

If you can test the users on your site to read something like a scarmbled statement, and 95% pass, I would say it is an incredibly good idea.