How To Build a Quantum Eavesdropper

KentuckyFC writes "Quantum encryption is perfectly secure, in theory. In practice, however, there are loopholes. Now Japanese scientists have designed a quantum eavesdropper that exploits one of these loopholes to listen in to quantum conversations. QC's security arises from the impossibility of making a perfect copy of a quantum object without destroying it — so the sender and receiver can always tell if they've been overheard. But it turns out that an eavesdropper can make imperfect copies and use them to extract information from a quantum message without alerting sender or receiver (abstract). The Japanese design does just this. That should worry banks and government agencies that have begun to use some of the commercial quantum encryption systems now available."

Comments

The obvious question is...

[clonan]

How imperfect is the snooped data?

Just because you COULD get data out doesn't mean it is actually usefull to do so.

Double Up On That Encryption

[b4upoo]

Why not use a more conventional, strong encryption method and then use quantum encryption on top of that? Getting an imperfect copy of a deeply encrypted message ought to be enough to drive anyone to drink including large numbers of enemy spies working in concert.