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The Quantum Hacking group works in the field of quantum cryptography and quantum information.
In quantum information science the information unit is not a bit, but rather a quantum bit – qubit.
A qubit may not only be zero or one, but also zero and one simultaneously!
In our work, we use photons as physical representation of qubits.
Quantum cryptography is a method of secure communication using qubits.
Such communication is based on the Heisenberg uncertainty principle. If an eavesdropper listens to qubits, she changes them, which is inevitably noticed by the legitimate users.
That is, any attempt of eavesdropping will be caught (in theory).
Our task is to make sure eavesdropping also gets caught in practice. In our daily work, we scrutinize implementations of quantum cryptography.
First, we play the role of the eavesdropper and try to hack quantum cryptosystems by taking advantage
of non-ideal behavior of the present-day quantum cryptographic hardware. Naturally, we often do find security problems.
Then, we suggest countermeasures, either practically by modifying the setups,
or theoretically by modifying the way of communicating. This is an iterative process. It should eventually make quantum cryptosystems harder to crack,
ultimately approaching the goal of absolute security.
Hacking cryptographic hardware
Practical implementations of quantum cryptography are quite complicated, and often leave loopholes to the eavesdropper. During the last few years, we have studied several hardware loopholes:
We introduced a faked-state attack, a general type of attack that exploits imperfections in Bobs optical scheme, and in one case fully implemented it on an installed quantum cryptography link.
How can we make a system secure when there are imperfections?
With the rules of quantum mechanics, we can prove security even in the presence of non-ideal equipment.
We try to incorporate different kinds of imperfections into the security proofs.
Our ultimate goal is a completely secure system, where all imperfections that cannot be eliminated are taken into account.
In addition, we are a member of the topical team Space-QUEST.
|Testing eavesdropping experiment in lab|