A zero - knowledge protocol for nuclear warhead verification

摘要

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.%未来回合的核武器控制最好是对核弹头直接进行检查，但这个过程需要使核查人员对所提交核材料的真实性非常有把握但又未提供其设计信息的相关程序。这个挑战此前只能得到部分应对，办法是采用复杂的自动化信息屏障，后者所依赖的是双方的极大信任。现在，Alexander Glaser、Boaz Barak和Robert Goldston开发出一种"零知识"中子成像技术，用它来确定核弹头的真实性。弹头的中子放射线图像会含有高度机密的信息，但在这一新方法中，数据是以正常方式处理、却是用预先加载了所宣称目标装置的放射线照片的一张"底片"的检测器来记录的。这样获得的对比结果对中子透射和发射提供了不同的测量值，它们能测出重金属从一个代表性测试目标的小偏移。