QUANTUM CRYPTOGRAPHY

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QUANTUM CRYPTOGRAPHY

• ABHINAV GUPTACSc 8230

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Introduction 1,2

• Quantum cryptography is an emerging technology in
  which two parties can secure network
  communications by applying the phenomena of
  quantum physics.
• The appealing characteristic of quantum
  cryptography is the possibility of distributing
  secret key between two users in a manner that it
  is impossible for a third party to eavesdrop
  without changing the quantum transmission and
  hence the eavesdropping is detected by users

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BB84 Protocol1,3

• The sender (traditionally referred to as Alice)
  and the receiver (Bob) are connected by a quantum
  communication channel which allows quantum states
  to be transmitted.
• In addition they communicate via a public
  classical channel.
• This protocol encodes the information in pair of
  non-orthogonal states.
• The usual polarization state pairs used are
  either the rectilinear basis of vertical (0) and
  horizontal (90), the diagonal basis of 45 and
  135(-45).

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BB84 Protocol Contd.. 3,4

• Alice creates a random bit (0 or 1) and then
  randomly selects one of her two basis to transmit
  it in.
• She then prepares a photon polarization state
  depending both on the bit value and basis.
• Alice then transmits a single photon in the state
  specified to Bob, using the quantum channel.
• This process is then repeated.
• Bob does not know the basis the photons were
  encoded in, so select a basis at random to
  measure in.
• After receiving all photons Bob communicate Alice
  on public channel.
• Alice broadcasts the basis each photon was sent
  in, and Bob the basis each was measured in.

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BB84 Protocol Contd.. 3,4
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BB84 Protocol Contd.. 3,4

• To check for the presence of eavesdropping Alice
  and Bob now compare a certain subset of their
  remaining bit strings.
• If a third party (Eve) has gained any information
  about the photons' polarization, this will have
  introduced errors in Bobs' measurements.
• If more than p bits differ they abort the key and
  try again.
• p is chosen so that if the number of bits known
  to Eve is less than this, privacy amplification
  can be used to reduce Eve's knowledge of the key
  to an arbitrarily small amount, by reducing the
  length of the key.

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Using Quantum Cryptography for securing Wireless
LAN networks, 2009 International Conference on
Signal Processing Systems5
Here telecommunication is not based on the
optical-fibers but rely on free space
line-of-sight-communication systems. Paper
suggest how we can integrate Quantum key
distribution in 802.11i (WLAN), by modifying the
4-way handshake to integrate the BB84 protocol as
presented
MIC message integrity code
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Implementations 2,3

• There are currently four companies offering
  commercial quantum cryptography systems id
  Quantique (Geneva), MagiQ Technologies (New
  York), SmartQuantum (France) and Quintessence
  Labs (Australia).
• Quantum encryption technology provided by the
  Swiss company Id Quantique was used in the Swiss
  state of Geneva to transmit ballot results to the
  capitol in the national election occurred on Oct.
  21, 2007. (Shows how secured method it is)
• The world's first computer network protected by
  quantum cryptography was implemented in October
  2008, at a scientific conference in Vienna. The
  network used 200 km of standard fibre optic cable
  to interconnect six locations across Vienna and
  the town of St Poelten.

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References

• 110th INTERNATIONAL CONFERENCE AND SEMINAR
  EDM'2009, SECTION III, JULY 1-6, ERLAGOL Quantum
  Cryptography Vladimir L. Kurochkin, Igor G.
  Neizvestny Institute ofSemiconductor Physics,
  Siberian Division, RAS, Novosibirsk, Russia
• 22009 Sixth International Conference on
  Information Technology New Generations, Quantum
  Cryptography A New Generation of Information
  Technology Security System by Mehrdad S. Sharbaf.
• 3 http//en.wikipedia.org/wiki/Quantum_cryptogra
  phy
• 4 Bennett, Ch. H., Brassard, G., Quantum
  cryptography public key distribution and coin
  tossing, IEEE Conference on Computer, Systems,
  and signal Processing, 1984
• 52009 International Conference on Signal
  Processing Systems Using Quantum Cryptography
  for securing Wireless LAN networks by A.Falahati
  , Hadi Meshgi

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Questions/Discussions