ZERO-KNOWLEDGE NEUTRON DETECTION

Transcription

1 ZERO-KNOWLEDGE NEUTRON DETECTION FIRST EXPERIMENTAL DEMONSTRATION OF A PHYSICAL ZERO-KNOWLEDGE PROTOCOL Francesco d Errico, Sébastien Philippe,! Robert J. Goldston, and Alexander Glaser Princeton Nuclear Futures Lab CVT Annual Meeting, Ann Arbor, MI, October 16, 2015 Revision 3

2 DETECTOR REQUIREMENTS NON-ELECTRONIC DETECTION & STORAGE 1. TRANSMISSION Capable of storing > 1,000 counts Preloads indistinguishable from measurement counts Insensitive to gamma radiation Sensitive to neutrons above selected thresholds Some thresholds of interest: 3 and 10 MeV 2. EMISSION (spontaneous and driven) Capable of storing thousands of counts No imaging at present Insensitive to gamma radiation Sensitive mainly to fission neutrons Energy threshold ~500 kev 2

3 SUPERHEATED EMULSIONS Fluorocarbon droplets in a steady superheated state. Vaporizations triggered by neutrons above selectable threshold energies. Can be totally insensitive to! s. 3

4 SUPERHEATED EMULSIONS Energy thresholds depend on composition Accurate temperature control required ~3% intrinsic e"ciency achievable Francesco d'errico, Radiation Dosimetry and Spectrometry with Superheated Emulsions Nuclear Instruments and Methods in Physics Research B, 184 (2001), pp

5 SUPERHEATED EMULSIONS Yale/Princeton Superheated Emulsions from Yale University with di!erent droplet loadings and sizes and commercial bubble detectors 5

6 SUPERHEATED EMULSIONS 1 Day 1 Day Bubbles in commercial polymer-based detectors expand noticeably in 24 hours. Bubbles in aqueous gel do not. 6

7 BUBBLE COUNTING 2D picture of exposed detector Linear behavior as a function of fluency 7

8 CONFIRMING THE AUTHENTICITY OF A NUCLEAR WARHEAD (WHILE LEARNING NOTHING ABOUT IT)

9 WHY ARE WARHEAD INSPECTIONS SO HARD? (AS SEEN FROM INSPECTOR S PERSPECTIVE) VERY LITTLE (IF ANY) INFORMATION ABOUT THE INSPECTED ITEM CAN BE REVEALED Some information may be shared in advance, but no additional information during inspection ADVERSARY/COMPETITOR HAS (DE FACTO) INFINITE RESOURCES ADVERSARY/COMPETITOR MAY BE EXTREMELY MOTIVATED (TO DECEIVE INSPECTOR) Stakes are very high (especially when the number of weapons drops below ~ 1,000) HOST HAS LAST OWNERSHIP OF INSPECTION SYSTEM BEFORE THE MEASUREMENT (and inspector never again has access to system a"er the measurement is complete) 9

10 PREVENTING THE EXCHANGE OF SENSITIVE INFORMATION DURING A RADIATION MEASUREMENT Trusted Information Barrier Measure (but sanitize) sensitive information Hard to authenticate and certify Single-bit observation Interactive Zero-knowledge Proof Never measure sensitive information Easy to authenticate and certify More complex observation S. Philippe, B. Barak, and A. Glaser, Designing Protocols for Nuclear Warhead Verification 56th Annual INMM Meeting, July 12-16, 2015, Indian Wells, California 10

11 THE BASIS FOR OUR ZERO-KNOWLEDGE PROTOCOL LOGICAL LAYER FOR AN ILLUSTRATED PRIMER ON ZERO-KNOWLEDGE PROOFS, SEE blog.cryptographyengineering.com/2014/11/zero-knowledge-proofs-illustrated-primer.html FOR A ZERO-KNOWLEDGE SUDOKU PROOF, SEE

12 PROVING THAT TWO OBJECTS ARE IDENTICAL PROOF FOR RADIOGRAPH EQUALITY + = Radiograph A Complement A + = Radiograph B Complement A OBJECTS A AND B ARE EQUIVALENT 12

13 PROVING THAT TWO OBJECTS ARE IDENTICAL PROOF FOR RADIOGRAPH EQUALITY + = Radiograph A Complement A + = Radiograph B Complement A OBJECTS A AND B ARE NOT EQUIVALENT 13

14 Credit: Sébastien Philippe Neutron generator Side Detectors (Fission Signature) Detector array (preloaded ) Complement of Reference Object (Secret) Collimator Object Presented For Inspection (Secret) As envisioned in: A. Glaser, B. Barak, R. J. Goldston, A Zero-knowledge Protocol for Nuclear Warhead Verification,! Nature, 510, 26 June 2014,

15 WHAT THE PROTOCOL ACHIEVES COMPLETENESS If the items are identical and both host and inspector follow the protocol, then the inspector will accept with probability p = 1 (#) n SOUNDNESS If the items are di!erent and the inspector follows the protocol, then, no matter what the host does, the inspector will reject with probability p $ 1 (#) n ZERO KNOWLEDGE As long as the host follows the protocol and presents matching items, the inspector gains no knowledge during their interaction except for the fact that the items match S. Philippe, B. Barak, and A. Glaser, Designing Protocols for Nuclear Warhead Verification 56th Annual INMM Meeting, July 12-16, 2015, Indian Wells, California 15

16 FIRST EXPERIMENTAL RESULTS The Conjurer, Hieronymus Bosch, 1502

17 EXPERIMENTAL SETUP AND SCENARIO WE WISH TO IDENTIFY CASES IN WHICH THE CUBE PATTERN HAS BEEN ALTERED WITHOUT GAINING ANY INFORMATION ABOUT THE CONFIGURATION IN CASES WHERE IT HAS NOT Collimated neutron beam 14-MeV (DT) generator Reference item consists of a combination of 2-inch cubes (aluminum and stainless steel) AL AL AL SS SS Reference item X X X X AL SS AL AL SS Staging area (with reference item) Detector array Detector positions Princeton Nuclear Futures Lab 17

18 Princeton Nuclear Futures Lab

19 EXPERIMENTAL RESULTS (VALID ITEM) Reference item X X X X AL SS AL AL SS Bubble count N MAX = Simulation Measurement #1 #2 #3 #4 #5 #6 #7 S. Philippe, R. J. Goldston, A. Glaser and F. d Errico, Experimental Demonstration of a Physical Zero-knowledge Protocol for Nuclear Warhead Verification, in preparation 19

20 EXPERIMENTAL RESULTS (A DRASTIC CHANGE) Reference item X X X X AL SSS AL AL SSS Mirrored item X X X SS AL X SS AL AL Bubble count N MAX = Simulation Measurement #1 #2 #3 #4 #5 #6 #7 S. Philippe, R. J. Goldston, A. Glaser and F. d Errico, Experimental Demonstration of a Physical Zero-knowledge Protocol for Nuclear Warhead Verification, in preparation 20

21 EXPERIMENTAL RESULTS (A SMALLER CHANGE) Reference item X X X X AL SSS AL AL SSS AL vs SS X X X X AL AL AL AL SS Bubble count Simulation Measurement #1 #2 #3 #4 #5 #6 #7 S. Philippe, R. J. Goldston, A. Glaser and F. d Errico, Experimental Demonstration of a Physical Zero-knowledge Protocol for Nuclear Warhead Verification, in preparation 21

22 NEXT STEPS / WAY FORWARD AT LAB-SCALE: DEMONSTRATING ZERO-KNOWLEDGE APPROACHES Experimental reproducibility of results Increasing Statistics: Maximize bubble loading & Counting E%ciency Zero-Knowledge isotopic comparison (Di!erent thresholds) Princeton Nuclear Futures Lab Data commitment schemes BEYOND LAB-SCALE: TOWARD FULL-SCALE INSPECTION SYSTEMS? Experiments with special nuclear materials in real-world conditions! Measurements at one of the CVT partner sites? Leveraging the virtues of unclassified research! Universal Test Object for Benchmark Purposes Source: U.S. Department of Energy (bottom) 22

23 ACKNOWLEDGEMENTS PPPL Andrew Carpe, PPPL Charles Gentile, PPPL Health Physics Department, PPPL YALE Margarita Gattas-Sethi Jesus Daniel Martin PRINCETON Yan Jie, Princeton University Microso! Research/Harvard University Boaz Barak