ON-LINE QLunch: Andreas Bluhm
Speaker: Andreas Bluhm from QMATH
Title: Position-based cryptography: Single-qubit protocol secure against multi-qubit attacks
Abstract:
While it is known that unconditionally secure position-based
cryptography is impossible both in the classical and the quantum
setting, it has been shown that some quantum protocols for position
verification are secure against attackers which share a quantum state of
bounded dimension. In this talk, we consider the security of the qubit
routing protocol. The protocol has the advantage that an honest prover
only has to manipulate a single qubit and a classical string of length
2n. We show that the protocol is secure if each of the attackers holds
at most n/2 - 3 qubits. With this, we show for the first time that there
exists a quantum position verification protocol where the ratio between
the quantum resources an honest prover needs and the quantum resources
the attackers need to break the protocol is unbounded. The verifiers
need only increase the amount of classical resources to force the
attackers to use more quantum resources. Finally, we show that the qubit
routing protocol is robust with respect to noise, making it appealing
for applications.
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https://ucph-ku.zoom.us/j/64018228108