quantum cryptography
Download
Skip this Video
Download Presentation
Quantum Cryptography

Loading in 2 Seconds...

play fullscreen
1 / 10

Quantum Cryptography - PowerPoint PPT Presentation


  • 146 Views
  • Uploaded on

Quantum Cryptography. By Jeff Hinson CS691, Summer 2009. Brief History. Idea born in late 60’s with Stephan Wiesner’s “Conjugate Coding” 1 st successful quantum exchange: October 1989 Charles Bennet and Gilles Brassard expand idea to “Quantum Key Distribution Channel”

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Quantum Cryptography' - tynice


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
quantum cryptography

Quantum Cryptography

By Jeff Hinson

CS691, Summer 2009

brief history
Brief History
  • Idea born in late 60’s with Stephan Wiesner’s “Conjugate Coding”
  • 1st successful quantum exchange: October 1989
  • Charles Bennet and Gilles Brassard expand idea to “Quantum Key Distribution Channel”
  • Has been a growing topic, especially in the past decade

CS691 Jeff Hinson Summer 2009

quantum channels
Quantum Channels
  • Needed equipment:
    • Fiber-optic cable
    • photon cannons on each end
    • filters for polarization
  • The idea:
    • Two computers: Alice and Bob
    • Alice polarizes a photon using a filter, sends to Bob
    • Bob receives photon, tries to read using a filter; guesses the polarization

CS691 Jeff Hinson Summer 2009

quantum channels cont
Quantum Channels (cont.)
  • Problem: unrealistic for regular use
    • unreliable, Bob must guess Alice’s polarization
    • normal internet connection still needed to verify accuracy of transmission on quantum channel
    • Photon-reading is slow, especially over large distances (~10kb/s)
  • Advantages:
    • difficult to hack; can tell if someone is eavesdropping on the line...

CS691 Jeff Hinson Summer 2009

quantum key distribution
Quantum Key Distribution
  • Makes quantum channels more realistic
  • The Idea:
    • use a quantum channel to send photons from Alice to Bob
    • Bob tells Alice what he thinks Alice’s polarizations were
    • Alice confirms/denies. Wrong bits are discarded, remaining bits are the new key
    • Key is used to encrypt/decrypt data send over a regular channel

CS691 Jeff Hinson Summer 2009

quantum key distribution cont
Quantum Key Distribution (cont.)
  • Cons
    • still expensive
    • slow connection over short distances
  • Pros
    • very secure; is difficult to guess the key
    • can tell if someone is eavesdropping:
      • measuring the photos will change their state
      • if Bob gets X number of bits wrong, eavesdropping is assumed; key discarded and a new channel is used to distribute the key

CS691 Jeff Hinson Summer 2009

eavesdropping
Eavesdropping
  • Intercepting/Resend
    • traditional approach; easily detectable
    • ideas to read momentum without measuring; study still shows it to be detectable
  • Beam-splitting
    • Photons difficult to send one at a time; if multiple photons are sent, eavesdropper can split beam to read one and pass others on without being detected
    • Is difficult to do, highly unreliable, and chance of detection still exists

CS691 Jeff Hinson Summer 2009

in the news
In the News...
  • Cambridge team found way to transmit up to 10mb/s over large distance (20km) on lower-cost components
  • Spain plans to release 1st metropolitan quantum cryptography network by 2010
  • Austrian scientists made successful quantum connection over 90mi distance

CS691 Jeff Hinson Summer 2009

conclusions
Conclusions
  • Quantum channel not likely to be used for regular connections anytime soon
  • Quantum Key Distribution is a good idea, and is very quickly becoming realistic
  • As scientific advancements are made, cost will decrease, and reliability and efficiency will increase
  • It sounds like a lot of fun, and makes for good dinner conversation....

CS691 Jeff Hinson Summer 2009

ad