Physical Layer Security
05/08/2017
IGNACIO AGUILAR SANCHEZ, ESA
CHARLES SHEEHE, NASA
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Outline
• Introduction
• Overview of secure channels
– COMSEC
– TRANSEC
– Non-crypto approaches
• Main physical layer security concepts
– Cryptographic spread spectrum
– Wiretap channel
– RF fingerprinting
• Prospects for CCSDS
– White, then Green Book
– Blue Books?
• Preliminary conclusions and follow-on
– Towards a White paper
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Introduction (1/2)
• Purpose
– Initiate CCSDS discussion and possibly future work
on physical layer security concepts, techniques
and related technologies as a future component of
space mission security engineering portfolio.
• Scope
– Today a short presentation introducing the subject
and its most important elements.
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Introduction (2/2)
• Motivation
– CCSDS has already tackled link and network layers on its
security engineering effort (e.g. SDLS).
– Certain threats can only be mitigated at physical layer (e.g.
denial of service by deliberate interference, signal
interception).
– But more interestingly physical layer has been
rediscovered to secure communication channels with
security services traditionally assigned to upper (data)
layers (e.g. authentication, confidentiality) and with a
promise of information-theoretic strong security (vs.
computationally-strong) without a key management
burden. Really?
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Overview of secure channels
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Cryptographic spread spectrum
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Wiretap channel approaches
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RF fingerprinting
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Prospects for CCSDS
• White Book followed by Green Book
– The subject is broad and complex, touching disciplines covered
by several CCSDS WGs…but could provide useful complements
and/or novel solutions to engineer security on space missions
– Research hot topic for wireless communications security with
strong interest by both civilian and governmental communities
– Deeper understanding of the subject as well as relevant
research results, expected benefits, future mission
requirements, etc. before deciding on any potential standard
– Joint SEC, RFM and S&CC task?
– Cautious but thorough approach!
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TOWARDS A WHITE PAPER
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•
Physical Layer Security
White Paper Outline
INTRODUCTION
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INTRODUCTORY SUBSECTIONS
REFERENCES
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OVERVIEW OF SECURE CHANNELS
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SECURE CHANNELS
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COMMUNICATIONS SECURITY (COMSEC)
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TRANSMISSION SECURITY (TRANSEC)
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NON-CRYPTOGRAHIC APPROACHES
MAIN PHYSICAL LAYER SECURITY CONCEPTS
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CRYPTOGRAPHIC SPREAD SPECTRUM
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SPREAD SPECTRUM
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PSEUDORANDOM SEQUENCES
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ISSUES
WIRETAP CHANNEL APPROACHES
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TRANSMITTER UNIQUENESS - RF FINGERPRINTING
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THE RADIO IN THE FINGERPRINT
THE REMOVAL OF INPUT FROM THE OUTPUT
COMPARISONS
ISSUES
CONCLUSION
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PROSPECTS FOR CCSDS
EXPECTED BENEFITS
REQUIREMENTS FOR PROSPECTIVE MISSIONS
RELATIONSHIP WITH EXISTING STANDARDS
IDENTIFIED DEFICIENCIES, FLAWS, AND LIMITATIONS IN EXISTING STANDARDS
GREEN BOOK ON PHYSICAL LAYER SECURITY
BLUE BOOKS
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THE WIRETAP CHANNEL
INJECTION OF ARTIFICIAL NOISE
KEY DERIVATION
CODING FOR SECRECY
CHANNEL UNIQUENESS
ISSUES
OVERVIEW
OPTICAL LINK ENCRYPTION AND KEY DERIVATION
CONCLUSION AND RECOMMENDATIONS
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Physical Layer Security paper process
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Develop Physical Layer paper outline
Public references for each section
Expand each section
Review of Physical Security Layer paper by Security Working
Group
Refine paper structure and content
RF Modulation Working Group buy in and provide feed back
on Physical Security Layer paper
Refine paper
Publish Physical Layer Security paper
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Physical Layer Security questions / notes
• Introduce the schematic of RF fingerprinting identification
process (transmitter+wireless channel+receiver).
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Some good readings
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C. E. Shannon, “Communication theory of secrecy systems,” Bell System Technical Journal, vol. 28, no. 4,
pp. 656–715, April 1949.
A. D. Wyner, “The wire-tap channel,” Bell System Technical Journal, vol. 54, no. 8, pp. 1355–1367, October
1975.
“Physical-Layer Security From Information Theory to Security Engineering”, M. Bloch and J. Barros,
Cambridge University Press, 2011.
“Algebraic Shift Register Sequences”, M. Goresky and A. Klapper, Cambridge University Press, 2012.
“Information Theoretic Security”, Yingbian Liang, H. Vincent Poor and Shlomo Shamai (Shitz), Foundations
and Trends in Communications and Information Theory, Vol. 5 Issue 4-5, 2008.
…..
…..
To be completed!
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