I have just sketched the protocols without error correction and in the ``ideal'' case where the information content for Bob is exactly zero. There are extended versions to these proofs that incorporate error correction, probabilistic commitment algorithms and non-zero information.

Since Bit Commitment is a possible foundation upon which other protocols such as coin tossing or two-party computation can be built, those latter protocols are weaker in some sense. The impossibility of BC does not mean that they cannot be secure. However, the same methods of attack can deal with some of them. Other ``no-go'' theorems been proved, such as (ideal) coin tossing, and some kinds of two-party computation[13].

Although defeated, Brassard, Crépeau and the other ``quantum cryptographers'' should not be forgotten. Alice's cheating scheme relies upon a machinery for quantum computation and storage that is way beyond the current technology, which is not the case for quantum communication protocols. One could, implement BCJL93 [5] -- QBC with error correction -- with today's technology, for a very secure bit commitment protocol.

Quantum key distribution, on the other hand, does not suffer from this problem, and Lo and Chau themselves have a recent paper proving its ``unconditional security''[14].

It is still disappointing that QBC seems to have been unable to go beyond what was already given by classic BC: Once the quantum computer becomes available, factoring large numbers becomes a possibility, and classical encryption dies. Here quantum cryptography can come to the rescue and restore security. But for ``post cold war cryptography'', the same quantum computer that burns factorization-based protocols, could also crack their quantum counterpart. One difference is that all the information can be kept on the classical version, so if sometime in the future we get our hands on a quantum computer, we will be able to go backwards in time, opening all communications ever received. Quantum protocols do not have this ``retroactive'' deciphering problem.