Unifying classical and quantum key distillation (original) (raw)
Related papers
arXiv: Quantum Physics, 2020
Extending the functionality and overcoming the performance limitation under which QKD can operate requires either quantum repeaters or new security models. Investigating the latter option, we introduce the \textit{Quantum Computational Hybrid} (QCH) security model, where we assume that computationally secure encryption may only be broken after time much longer than the coherence time of available quantum memories. We propose an explicit ddd-dimensional key distribution protocol, that we call MUB-\textit{Quantum Computational Timelock} (MUB-QCT) where one bit is encoded on a qudit state chosen among d+1d+1d+1 mutually unbiased bases (MUBs). Short-term-secure encryption is used to share the basis information with legitimate users while keeping it unknown from Eve until after her quantum memory decoheres. This allows reducing Eve's optimal attack to an immediate measurement followed by post-measurement decoding. \par We demonstrate that MUB-QCT enables everlasting secure key distributi...
Quantum-locked key distribution at nearly the classical capacity rate
Physical review letters, 2014
Quantum data locking is a protocol that allows for a small secret key to (un)lock an exponentially larger amount of information, hence yielding the strongest violation of the classical one-time pad encryption in the quantum setting. This violation mirrors a large gap existing between two security criteria for quantum cryptography quantified by two entropic quantities: the Holevo information and the accessible information. We show that the latter becomes a sensible security criterion if an upper bound on the coherence time of the eavesdropper's quantum memory is known. Under this condition, we introduce a protocol for secret key generation through a memoryless qudit channel. For channels with enough symmetry, such as the d-dimensional erasure and depolarizing channels, this protocol allows secret key generation at an asymptotic rate as high as the classical capacity minus one bit.
Extended analysis of the Trojan-horse attack in quantum key distribution
2018
The discrete-variable quantum key distribution protocols based on the 1984 protocol of Bennett and Brassard (BB84) are known to be secure against an eavesdropper, Eve, intercepting the flying qubits and performing any quantum operation on them. However, these protocols may still be vulnerable to side-channel attacks. We investigate the Trojan-horse side-channel attack where Eve sends her own state into Alice's apparatus and measures the reflected state to estimate the key. We prove that the separable coherent state is optimal for Eve among the class of multimode Gaussian attack states, even in the presence of thermal noise. We then provide a bound on the secret key rate in the case where Eve may use any separable state.