Composable security in relativistic quantum cryptography


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Date

2019-04

Publication Type

Journal Article

ETH Bibliography

yes

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Abstract

Relativistic protocols have been proposed to overcome certain impossibility results in classical and quantum cryptography. In such a setting, one takes the location of honest players into account, and uses the signalling limit given by the speed of light to constraint the abilities of dishonest agents. However, composing such protocols with each other to construct new cryptographic resources is known to be insecure in some cases. To make general statements about such constructions, a composable framework for modelling cryptographic security in Minkowski space is required. Here, we introduce a framework for performing such a modular security analysis of classical and quantum cryptographic schemes in Minkowski space. As an application, we show that (1) fair and unbiased coin flipping can be constructed from a simple resource called channel with delay; (2) biased coin flipping, bit commitment and channel with delay through any classical, quantum or post-quantum relativistic protocols are all impossible without further setup assumptions; (3) it is impossible to securely increase the delay of a channel, given several short-delay channels as ingredients. Results (1) and (3) imply in particular the non-composability of existing relativistic bit commitment and coin flipping protocols.

Publication status

published

Editor

Book title

Volume

21

Pages / Article No.

43057

Publisher

IOP Publishing

Event

Edition / version

Methods

Software

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Date collected

Date created

Subject

quantum cryptography; relativistic quantum cryptography; bit commitment; composable security; relativistic quantum communication; abstract cryptography; quantum resource theories

Organisational unit

03781 - Renner, Renato / Renner, Renato check_circle

Notes

Funding

165843 - Fully quantum thermodynamics of finite-size systems (SNF)

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