  Catch 22 of cryptography - "Before two parties can communicate in secret,
they must first communicate in secret". The weakness of classical cryptographic
communication systems is that secret communication can only take place after a
key is communicated in secret over a totally secure communication channel. Here
comes quantum key distribution which takes advantage of certain phenomena that
occur at the subatomic level, so that any attempt by an enemy to obtain the
bits in a key not only fails, but gets detected as well.
