Source-linked AI summary
Security proof for cryptographic protocols based only on the monogamy of Bell's inequality violations
Marcin Pawlowski
TL;DR
The paper asks which quantum-mechanical properties are needed for QKD to remain secure in more general theories, given that no-signaling is known to suffice. It derives security conditions from Bell-inequality monogamy and shows that secure communication can also be possible in signaling theories.
Problem
Whether QKD remains secure in post-quantum theories depends on which properties of quantum mechanics warrant that security; no-signaling was known to be sufficient.
Source: p. 1Method
The authors derive sufficient security conditions for a CHSH-based QKD protocol from monogamy relations, without assuming no-signaling.
Source: pp. 2, 4Results
Monogamy conditions can suffice for QKD security even in signaling theories, so no-signaling is sufficient but not necessary.
Source: p. 3Takeaways & Limitations
The security analysis can apply to theories accessible to communicating parties beyond those that obey no-signaling.
Source: pp. 3–4The signaling-theory illustration uses a particular three-party distribution family, which is signaling for almost all parameter combinations while satisfying NS-monogamy.
Source: pp. 1–2
Abstract
from arXiv · showhide
We show that monogamy of Bell's inequality violations, which is strictly weaker condition than no-signaling is enough to prove security of quantum key distribution. We derive our results for a whole class of monogamy constraints and generalize our results to any theory that communicating parties may have access to. Some of these theories do not respect no-signaling principle yet still allow for secure communication. This proves that no-signaling is only a sufficient condition for the possibility of secure communication, but not the necessary one. We also present some new qualitative results concerning the security of existing quantum key distribution protocols.