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Hardware hackers defeat quantum crypto

Tripping the light fantastic

Security researchers using hardware hacking techniques have unearthed generic flaws in supposedly ultra-secure quantum cryptography systems.

The security of quantum cryptography hinges on using the fundamental properties of quantum physics for quantum key exchange. Any attempts to monitor this exchange would inevitably be detected as increased noise on the line and an abandoned data exchange. That principle remains solid and the attack, like others before it, relies on exploiting implementation flaws.

This particular crypto-busting technique, which uses off-the-shelf but expensive hardware, relies on remotely manipulating a photon detector at the receiver's end of a supposedly secure link. Commercial systems from MagiQ Technology's QPN 5505 and ID Quantique Clavis2 systems were demonstrated as potentially vulnerable by a team of computer scientists from Norway and Germany.

Researchers from Norwegian University of Science and Technology (NTNU), the University of Erlangen-Nürnberg and the Max Planck Institute for the Science of Light in Erlangen are working with manufacturers to develop countermeasures. The loophole - which relies on specially tailored bright illumination - is likely to be common in most QKD systems using avalanche photodiodes to detect single photons, the researchers warn.

“Unlike previously published attempts, this attack is implementable with current off-the-shelf components,” explained Dr Vadim Makarov, a researcher in the Quantum Hacking group at NTNU. “Our eavesdropping method worked both against MagiQ Technology's QPN 5505 and ID Quantique Clavis2 systems.”

The hack pulled off by the team is complex and might involve an initial outlay of $50,000 or more, potentially within the reach of industrial spies and certainly in the scope of intelligence agencies.

Quantum key distribution systems became commercially available around five or six years ago and are used for the secure exchange of highly sensitive material by banks and governments, so a major up-front investment in equipment and expertise is certainly possible.

The researchers have published their preliminary findings in a letter to the August 29 edition of academic journal Nature Photonics.

An overview of the research, together with pictures of the hacking rig, can be found here. ®

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