http://www.maths.mq.edu.au/~steffen/...ort/node7.html

i just found this on google, it gives good insight into anti/symmetric cryptography.

from what i know, coupled with this, i still can't think why the key must be n(n-1)/2.

should it be a function? like p = n(n-1)/2 . could it be used to transform some ascii string into some larger bit number?

in short, i don't know.