Quantum key distribution based on private states: unconditional security over untrusted channels with zero quantum capacity

Abstract

We prove unconditional security for a quantum key distribution (QKD) protocol based on distilling pbits (twisted ebits) [quant-ph/0309110] from an arbitrary untrusted state that is claimed to contain distillable key. Our main result is that we can verify security using only public communication -- via parameter estimation of the given untrusted state. The technique applies even to bound entangled states, thus extending QKD to the regime where the available quantum channel has zero quantum capacity. We also show how to convert our purification-based QKD schemes to prepare-measure schemes.

Final version for IEEE TIT

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Cited by in corpus (30)

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• Weak randomness completely trounces the security of QKD
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• Energy-constrained private and quantum capacities of quantum channels
• Multipartite secret key distillation and bound entanglement
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• Amortization does not enhance the max-Rains information of a quantum channel
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• Upper bounds on device-independent quantum key distribution
• Entanglement Theory and the Quantum Simulation of Many-Body Physics
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