trap-door function
A special class of {one-way
function}, which is reversible if you know a certain secret
associated with the function.
{(http://www.rsasecurity.com/rsalabs/faq/2-3-2.html)}.
{(http://www.ieor.berkeley.edu/~jshu/knapsack/Review/OverviewPK.html)}.
(2003-05-22)