Well if it were that easy then I think everyone would do it. If the information is high profile enough they'll make you tell them whether you say you forgot or not.
If you actually did forget then I don't know. They'd probably make you remember.
oh it is. What will they do beat you up??
that way you'll be more worried about more incriminating evidence that can be uncovered.
If you say you forgot, you forgot. They cannot get into your head.
the most they do is put you under yellow bulb, keep asking and intimidating you. That's it.
if real torture is authorized then you'll sing like a canary anyway.
if no torture then you can just keep bullshitting them. Just tell them random passwords. What can they do??
its like this..
Hey, what's your password...
(give a dumb look) .. Um... I keep forgetting it.
Maybe.. "uranasshole3825"..