Quantum Cryptography

1
Quantum Cryptography

• Introduction and Networking/Security Issues
• Presented by Jeff Swauger, CISSP

2
What is Quantum Cryptography?

• Quantum Cryptography is a method of data
  encryption based upon
• basic, fundamental nature of the universe
  (quantum mechanics)
• Vernam cypher encryption
• advanced optical communications technology
• encoding of information in quantum entangled
  photon packets
• Provides Perfectly Secure Communications
• absolutely secure transmission of cryptographic
  keys, even against quantum computers
• any eavesdropping of key transmission is
  demonstrably detectable (man in middle attacks,
  etc.)
• security based on inviolability of facts of
  physics and natural law
• Development of this area has taken entirely
  secure communications to the near marketable
  development stage

3
Quantum Cryptography Benefits

• Secure, unbreakable, transmission of data with
  intrusion/attack detection
• Multiparty quantum key distribution possible
• Beyond line of sight quantum cryptographically
  secured communications possible
• Wide variety of systems can benefit
• various on-the-move ad hoc networks can maintain
  absolute security
• remotely distributed fixed networks can maintain
  absolute security
• Practical implementation requires knowledge of
  several associated costs
• Authentication
• Communications
• Computation time/space (processing/memory
  requirements)

4
Basic Quantum Mechanics

• Quantum Mechanics describes the way the universe
  operates at the smallest fundamental level,
  particles, molecules, and photons
• In principle, quantum mechanics describes
  everything, but for almost all macroscopic events
  classical physics is easier and as accurate
  (although it falls apart at atomic and sub-atomic
  levels)
• Key principles used in quantum cryptography
• Heisenbergs Uncertainty Principle ?x?p ? h
• Principle of indeterminacy, universe is
  non-deterministic
• Schrödingers Cat paradox, state of a
  particle/photon is not defined until examined or
  interaction with another particle/photon
• Quantum Entanglement
• Quantum effects are not visible
• in macro world but they are there
• Demo of Uncertainty Principle
• Classical physics does not predict
• Quantum effects are strange
• As uncertainty in energy decreases
• Uncertainty in position approaches ?
• Tunnel diodes rely on this principle

5
If You Dont Understand Or Feel Comfortable With
This, Youre In Good Company

• The statistical and probabilistic nature of
  quantum mechanics is difficult to understand and
  have faith in
• God does not play dice with the universe,
  Albert Einstein
• Anyone who is not deeply disturbed by quantum
  mechanics doesnt understand it, Schrödinger
• I dont like it, and I wish I never had anything
  to do with it, Max Plank
• Einstein was alarmed by the concept of quantum
  entanglement and referred to it as spukhafte
  Fernwirkungen which means Spooky Actions at a
  Distance
• Prof. John Preskill, (Caltech) The human mind
  seems to be poorly equipped to grasp the
  correlations exhibited by entangled quantum
  states.
• Dr. Jim Franson (APL) Roughly speaking photon 2
  somehow receives this information

6
Quantum Entanglement

• Entanglement arises when particles interact and
  become correlated such that the wavefunction of
  two physical objects is not expressible as the
  product of the wave functions of the individual
  particles (PEV Paradox)
• These particles display a strange correlation to
  each other, e.g. two separated entangled
  electrons can have their spins anticorrelated
• Entanglement has been produced experimentally in
  laboratory conditions
• Phenomenon plays key role in quantum cryptography
• Still continuing controversy as to how
  entanglement really works, not well understood
• The Corsican Brothers, by Dumas, displays a
  type of entanglement
• two brothers joined at the side at birth -
  after separation they retain a strange
  correlation with each other - at any separation
  they form one body
• Not completely technically correct, but
  understood at least as well as quantum
  entanglement

7
Quantum Cryptography Basics

• Quantum Key Distribution
• No passive eavesdropping possible due to
  Shröedinger Indeterminacy Principle ?
  unconditional secrecy
• Vernam cipher (one time pad) encryption used
• Plaintext encrypted via XOR against key using
  Vernam cipher as a result ciphertext is
  completely random ? unconditional secrecy
• Vernam cipher requires two copies of the pad or
  key
• Unbreakable if pad composed of truly random data,
  never used more than once, and kept secure
  (capture of key can render system useless,
  quantum effects prevent anyone from intercepting
  key)
• Quantum Key Distribution Vernam cipher system
  QUANTUM CRYPTOGRAPHY most secret possible system
  consistent with the laws of physics
• Requires use of optical based communications,
  range limited currently (approx. 1.8 km free air
  _at_ sea level, 43 km direct fiber)
• Secure against even quantum computers!

8
Ideal Quantum Key Distribution Protocol

• User 1 sends / - - \ - -
  /
• User 2 sets X X X X X
• User 2 receives / - \ / \ - / -
  
• User 2 tells User 1 (publicly) what his settings
  were
• User 1 tells User 2 (publicly) which settings
  were correct 2, 6, 7, 9
• Both users keep those states correctly measured
• \ - -
• Using \, 0 and - , / 1 yields
• 0 0 1 1 The Shared
  Key
• Distribution method - optical photon pulses,
  polarization of light pulses carries information,
  polarization measured by attacker in the middle,
  User 1 can detect from User 2s response that
  system was attacked, also very difficult to
  attack (fast photon counters coupled with
  significant computational power and picosecond
  response lasers

9
Quantum Cryptography Network Implementations

• By direct, line of sight transmission over open
  atmosphere _at_ sea level, (currently demonstrated
  as practical, range limit 2 km)
• Dedicated, switchless high quality fiber optic
  connection (currently demonstrated as practical,
  range limit 43 km)
• Free-space channels
• Aircraft - LEO Satellite link
• Earth (MSL) - LEO Satellite Link
• Earth (10,000 ft) - GEO Satellite Link

10
Quantum Cryptography Security Issues

• Vernham cypher uses single key, not PKI such as
  PGP
• Key completely secure during transmission thanks
  to quantum cryptography
• Key compromise still possible by usual methods
• Physical security breaches on either end
• Network security breaches if computers connected
  to other networks (possible as QC usually used to
  distribute key only, using other, more
  conventional methods for cyphertext transmittal)
• Tempest issues
• Insider attacks by trusted personnel
• While these issues exist, environments likely to
  use Quantum Cryptography (Military/Intel, large
  corporations and banks) should have adequate
  assets to prevent this (in a perfect world)

11
Quantum Computing Challenges

• Application of Quantum Cryptography in networks
• Unicast
• Multicast
• Ad-hoc multicast
• Insertion in combined terrestrial/space networks
• presence of amplifiers, switches, etc.
• Advances in optical fiber technology
• Advances in general optical components (switches)
• Advanced in quantum bit source technology
• Implementation is key, engineering is the art of
  the practical
• Prior to 1990 quantum computing and cryptography
  was impossible due to technological barriers
• To expand quantum cryptography, optical network
  devices must be improved with respect to quantum
  mechanical principles

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Experimental Implementations

• Boston University
• British Telecom
• DERA
• IBM
• Johns Hopkins Applied Physics Lab
• KTH
• LANL
• MITRE
• Norwegian Telecom
• University of Geneva
• University of Illinois
• ...