What can you do to make audio captcha's harder? Add more voice! This is exactly what google has done on their updated audio captcha. This really helps, you need a much more fine grained and larger voice model to trancribe that. I still think it is doable, but the amount of training work that is involved scares at least me away from actually doing it. This is the same for the latest image captchas, trying to segment them is hard (matching the broken segments to determine the charachter with a statistical model is relatively easy). tedd wrote: > > Perhaps I'm underestimating the capabilities of bots and > overestimating the abilities of humans. I suspect that the > distribution of both camps have an overlap and therein lies the > problem. The problem may not have a solution. > > But to bring this back to my intent -- my intent here is to provide a > simple audio CAPTCHA that could be used by anyone to provide some > degree of protection for their personal use THAT would also be > accessible to screen readers. It's not foolproof, but it appears to > work in that regard. > I think any captcha that is different from a standard library one will help, you should just know that if someone is really convinced to break it, he/she can. So think of a captcha and implement it quietly (no bragging how good it is, that will draw the wrong attention). Standard bots will not be able to parse it and only if you have a high profile site it will be economally viable for spammers to break it.
What about semi-automatic bots? They load page and fill in all the details in the form, and they pass the captcha *shit* to you, you type over the code and the bot can start spamming right? About your dot-captcha program tedd, it's another trick, it hasn't been used yet, so somebody needs to look at it to crack. Like Jochem said, if someone really wants to break it, he will do it. Making a real though CAPTCHA isn't that hard, it's hard to create a CAPTCHA that's easy to the user, but very hard to bots. I was thinking about animation, very simple like a moving dot. "Did it move from left to right, right to left, top to bottom or bottom to top?" As animated images/flash/movies are really though items to parse for a bot. So just creating an AVI made up from a few simple frames. Everyone can see if which side the dot moves. But yet, there's no movie support in PHP, i discussed this on the internals list, but nobody seems interested, and this is the case i need it again :). I was thinking about creating random frames from PHP(also a random number, with different frame rates) and then creating an movie from that frames. I prefer no compression then, because that would require the user to install decoders. I think these days every user has a browser supporting inline movies right? I know, this wouldn't stop the semi-automatic bots, but i think these are very hard to stop. (Unstoppable maybe?) Tijnema -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
