  So-called non-local boxes, which have been introduced as an idealization-in
different respects-of the behavior of entangled quantum states, have been known
to allow for unconditional bit commitment between the two involved parties. We
show that, actually, any possible non-local correlation which produces random
bits on both sides can be used to implement bit commitment, and that this holds
even when the parties are allowed to delay their inputs to the box. Since a
particular example is the behavior of an EPR pair, this resource allows for
implementing unconditionally secure bit commitment as long as the parties
cannot entangle their Qbits with any other system.
