> > > > (*) Of course, it's better to use sound sources that are hard to > > identify, and are ideally not available to the attacker; else he could > > obtain the same sounds and subtract them from the audio. I think some > > random pitch shifting (tremolo) would help against this. > > OK. Use voice recognition.
We all know how well those work! Using IVR systems which reliably detect what I say when I speak slowly and clearly without sounding like Basil Faulty speaking to Manuel are non existent. So surely the reverse would be true of any voice recognition system applied to voice captchas..... _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/