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A zero-knowledge protocol for nuclear warhead verification


The verification of nuclear warheads for arms control involves a paradox: international inspectors will have to gain high confidence in the authenticity of submitted items while learning nothing about them. Proposed inspection systems featuring ‘information barriers’, designed to hide measurements stored in electronic systems, are at risk of tampering and snooping. Here we show the viability of a fundamentally new approach to nuclear warhead verification that incorporates a zero-knowledge protocol, which is designed in such a way that sensitive information is never measured and so does not need to be hidden. We interrogate submitted items with energetic neutrons, making, in effect, differential measurements of both neutron transmission and emission. Calculations for scenarios in which material is diverted from a test object show that a high degree of discrimination can be achieved while revealing zero information. Our ideas for a physical zero-knowledge system could have applications beyond the context of nuclear disarmament. The proposed technique suggests a way to perform comparisons or computations on personal or confidential data without measuring the data in the first place.

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Figure 1: A zero-knowledge protocol to prove that two cups contain the same number of marbles.
Figure 2: Experimental set-up with neutron source, neutron collimator, British Test Object in container, and detector array.
Figure 3: Results of MCNP5 simulations for interrogations of the British Test Object in two different orientations.
Figure 4: Results of MCNP5 simulations for two notional diversion scenarios.


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This project was supported by Global Zero and the US Department of State, the Princeton Plasma Physics Laboratory (DOE contract DE-AC02-09CH11466) and in-kind contributions from Microsoft Research New England. We thank D. Dobkin, F. d’Errico, J. Fuller, D. MacArthur, J. Mihalczo, S. Philippe and M. Walker for discussions and feedback. We thank S. Philippe (Princeton University) for graphics in Fig. 2. All simulations were run on Princeton University’s High Performance Cluster.

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A.G. was project leader and performed all of the MCNP5 calculations. B.B. and R.J.G. contributed, along with A.G., to developing the overall approach and the application of zero-knowledge proofs to warhead verification.

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Correspondence to Alexander Glaser.

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The authors declare no competing financial interests.

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Glaser, A., Barak, B. & Goldston, R. A zero-knowledge protocol for nuclear warhead verification. Nature 510, 497–502 (2014).

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