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.
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