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Capcha verification with sound

Posted: Sat Sep 10, 2005 2:36 am
by bokehman
I am trying to produce a CAPCHA script with audio back up. I will record the letters and numbers into individual audio files and then join the files dynamically. For example if the code was: a1bDTg34 I want to join those sound bites together and send them to the client. What file format would you recommend and how would I join them using PHP.

Posted: Sat Sep 10, 2005 7:22 am
by feyd
pcm-wav or aiff or mp3. I've pick one of the first two over the latter. wav is probably the most universal and natively playable.

Posted: Sat Sep 10, 2005 7:31 am
by bokehman
Thanks! I've got something together now that stiches .WAVs.

Posted: Sat Sep 10, 2005 9:58 am
by Roja
Another suggestion is reduce the size.. realistically, on THESE forums (extremely active), we have 17,000 members. A unique captcha for each using letters and numbers [0-9A-Z] would only take 4 characters. I use 6 characters for confirmation codes in most of my applications, and simply use hex [0-9A-F], which gives me over a million unique captcha's. Once a user is signed up, you can reuse the captcha's, and making it any longer makes it very challenging for real users.

Of course, all but the most complex captcha's have already been defeated by automated software, so their value is debatable. ( http://sam.zoy.org/pwntcha/ ).

Posted: Sun Sep 11, 2005 8:50 pm
by bokehman
Thanks for the advice. I have trimmed it back to four characters. Here's the script. What do you think?