  Mayers, Lo and Chau proved unconditionally secure quantum bit commitment is
impossible. It is shown that their proof is valid only for a particular model
of quantum bit commitment encoding, in general it does not hold good. A
different model of unconditionally secure quantum bit commitment - both
entanglement and disentanglement-based - is presented. Even cheating can be
legally proved with some legal evidences. Unconditionally secure quantum bit
commitment can be established on the top of unconditionally secure quantum coin
tossing, which is also claimed to be two-way impossible.
