We also understand that people will say anything to get the torture to stop.

When the intelligence community let it be known that Khalid Sheikh Muhammad confessed to planning 9-11, the response from the public was tempered by the almost universal recognition that he had been waterboarded hundreds of times before he "confessed".

At that point, he would have confessed to killing JFK and Lincoln just to stop them from slow-motion drowning him.

There is a problem with that - even true facts could be deceiving. The only way to verify outside of checking is to continue torturing which defeats the reasons for the person surrendering the information in the first place.

Not necessarily; you could torture someone for something like a key to an encrypted file. This is something difficult to guess, but easy to verify the correctness of. I am not saying that torture is justified in this scenario, but only that it is not true that "to verify outside of checking is to continue torturing which defeats the reasons for the person surrendering the information in the first place".

TrueCrypt plausible deniability. Once I have surrendered the key for the outside container, what do you do?

The introduction of plausible deniability in encryption is actually the ultimate nightmare from an ethic perspective:

The torturer, of course, knows about plausible deniability. And of course, technically, plausible deniability is not limited to two levels (outer and inner volume), but can be performed on an arbitrary number of levels. From the torturer perspective, he has to continue to torture forever, because any passphrase revealed might not be the one for the "true" stash of information. In reality, the torturer does not stop at the first possible instance of revelation, but on the last (which will never be in this case).

Plausible deniability actually prevents the torturer from rewarding the victim for the revelation of information by ending his/her pain. Instead, plausible deniability opens the spiral of endless violence.

"Hand over the jew gold you jew, i know you have two bags, one real one fake, give me both."