Quantum hackers have performed the first ‘”invisible” attack on two commercial quantum cryptographic systems by using lasers on the systems, Nature News reports.
By using lasers—which employ quantum states of light to encrypt information for transmission—the hackers were able to crack the encryption keys on the commercial quantum systems, without any trace of the hack.
Quantum cryptography has been considered an unbreakable mean of encryption. It is based on the principle that you cannot make measurements of a quantum system without disturbing it, which, in theory, makes it impossible to intercept a quantum encryption key without an obvious disruption.
“Our hack gave 100 percent knowledge of the key, with zero disturbance to the system,” Nature quoted Vadim Makarov at the Norwegian University of Science and Technology, as saying.
In standard quantum cryptographic techniques, the sender–called “Alice” for convenience–generates a secret key by encoding classical bit values of 0 and 1 using two different quantum states of photons, or particles of light.
The receiver, “Bob,” reads off these bit values using a detector that measures the quantum state of incoming photons. In theory, an eavesdropper, “Eve,” will disturb the properties of these photons before they reach Bob, so in case Alice and Bob compare parts of their key, they will notice a discrepancy.
In Makarov and colleagues’ hack, Eve circumvents this constraint by “blinding” Bob’s detector by shining a continuous, 1 – milliwatt laser at it. While Bob’s detector is disabled, Eve can then intercept Alice’s signal.