This might sound like a
contradiction in terms but there is an interesting letter in Nature
Photonics from a group of researchers at the Norwegian University of
Science and Technology who are studying quantum cryptography.
The tricky thing with cryptography is not so much the invention of a super-clever code but the need to distribute the security key. When you think in terms of a physical security system such as a bank vault you will be able to spot whether the key goes missing and if you keep the key in a secure
place you will be able to prevent anyone taking a copy.
With digital security you're in a tricky position. If you send the key in one message and
then send the encrypted message separately you have to hope that the system is secure. If the key is intercepted in transit you will be none the wiser and the cryptography will be blown. Worse than that you will have a false sense of security.
Quantum cryptography promised to knock this problem on the head with the use of some
arcane science. In the world of quantum a particle exists in a number
of potential states and the state isn't determined until the particle
has been observed by a photodiode quantum detector. Modern security
systems mix some quantum particles in with the data stream. Then, if
the stream is intercepted, the quantum particles will change their
state and the intended recipient will realise that something has gone
wrong.
The problem, according
to the researchers, is that these systems can be spoofed. Bright
lights can be used to dazzle the sensors and then a laser can send a
signal that replaces the original data stream without the tell-tale
intruder alert.
It all sounds a bit
theoretical but the underlying message is that even the most
fantastic security system can be defeated with a lot of hard work.
And lasers.