By Nicholas Moradi

CST 300L Fall 2012

QUANTUM CRYPTOGRAPHY

• In 1979 Quantum Cryptography was established by Gilles Brassard

For security reasons the key had to be unable to view to everyone but the two connecting to each other. They wanted to make it so “it required the legitimate parties to share a secret key” (Brassard, 2005). They wanted to make it so that no eavesdropper could read into it because the eavesdropper could intercept it and read it if it were crack-able. In 1983 the researchers developing this technology “realized how much easier it would be to use the quantum channel to transmit an arbitrarily long random secret key” (Brassard, 2005). This would require both users receiving the message to have quantum computers too. This way if an intruder tried to get into the channel the key would be thrown away and the message lost forever

HISTORY

Also in 1983 the Quantum Key Distribution was created to send out public keys when a user downloads a file. In the 1990’s the Quantum Key Distribution was reinvented, it used entanglement which further increased the security of devices and machinery.

HISTORY CONT…

Gilles BrassardA video of him explaining Quantum Cryptography: http://www.youtube.com/watch?v=wpUflVa3rGI

HOW IT WORKS

This picture explains how quantum cryptography works.Step one: User A sends a photon through the slot 0 or 1, while recording the different movements of it.Step two: User B randomly filters the slot used for detection and recors both bit value and polarization.Step 3: If an eavesdropper User C tries reading the data, quantum mechanics prohibit her from accessing both channelsStep 4: User B then sends User A the information of the sequence of filters that User B recordedStep 5: User B sends the bits recorded to User A. After the bits match up User A sends the data.

With quantum cryptography it does “not only allows for the creation of an unbreakable cryptosystem, it also reduces the possible harm that could result from a "man in the middle" attack” (Smith, 2004). After the intended public key is given out I can’t be used again by the same user for the same file. Quantum Cryptography allows “the use of one time pads allows for completely unbreakable encryption (provided that, as the name implies, they are used only once!). The use of quantum cryptography allows for a limited but unbreakable means of distributing these one time pads. Despite its limitations, quantum cryptography may be the only completely secure encryption system that the world will ever know” (Smith, 2004).

HOW IT WORKS CONT.

SECURITY

Whatever worries there are for people who use the internet fear not “quantum cryptography addresses the most worrisome aspect of current public key cryptography, which powers Web browsers, applications like Pretty Good Privacy (PGP), and workhorse protocols like SSH and SSL”(McCullagh, 2003). It creates keys to large and to hard for a human to compute. Connection with quantum cryptography are usually always point to point and if connections are intercepted “the intended recipients will see an increase in the error rate of the data received, allowing them to detect if it has been accessed” (Ferguson, 2008). So in conclusion if someone tries to tamper with the information the data is wiped.

BRINGING THE QUANTUM HOME

With our advances on this unbreakable technology, it comes to the front doors of commercial use. Quantum cryptography “has until now needed a dedicated fibre separate from that used to carry data”(Palmer, 2012). Until now “the requirement of separate fibers has greatly restricted the applications of quantum cryptography in the past, as unused fibers are not always available for sending the single photons, and even when they are, can be prohibitively expensive” (Wickham, 2012). This means that these technologically advanced data protocols can now be accessed over broadband cables.

With technological advances quantum computing was brought to the homestead. Researchers at the Max Planck Institute of Quantum Optics in Germany “claimed the first elemental quantum network where information was stored in the quantum state of a single atom using an approach which could be done at larger scale. The atom emits a photon, which encodes the atom's state in its polarity. The photons were then transferred to another network node at another laboratory connected by an optical fiber to send information” (LaMonica, 2012). This means that the cables containing quantum coding can be transferred using normal fibre cables, which in turn means that users someday will be able to use this technology at home!

BROADBAND CABLES

Using a connection a detector is set up to detect if a photon arrives up to the micro-second. This photon holds the quantum key. The photon travels through the connection with “the ultra-high shutter-speed snapshot detector responds largely to just the single photon signals and is insensitive to the scattered light caused by the other data signals. This allows the weak single photon signals to be recovered from the fibre” (Leyden, 2012). This means through the broadband cable the photon is subject to different orientations that allow the light from shutters to determine the data.

HOW IT WORKS

References

Brassard, G. (2006, April 11). Brief History of Quantum Cryptography: A Personal Perspective. Quantum Physics. Retrieved December 11, 2012, from arxiv.org/abs/quant-ph/0604072v1

Ferguson, T. (2008, October 8). Network security makes a quantum leap | Security & Privacy - CNET News. Technology News - CNET News. Retrieved December 11, 2012, from http://news.cnet.com/8301-

1009_3-10064219-83.html

LaMonica, M. (2012, April 12). Physicists connect the dots on quantum computing | Cutting Edge - CNET News. Technology News - CNET News. Retrieved December 11, 2012, from http://news.cnet.com/8301-

11386_3-57413022-76/physicists-connect-the-dots-on-quantum-computing/

Leyden, J. (2012, November 20). Quantum crypto - with nothing more than STANDARD broadband fibre • The Register. The Register: Sci/Tech News for the World. Retrieved December 11, 2012, from

http://www.theregister.co.uk/2012/11/20/quantum_crypto_breakthrough/

Markoff, J. (2012, November 20). Scientists Find Cheaper Way to Ensure Internet Security. New York Times. Retrieved December 11, 2012, from www.nytimes.com/2012/11/20/technology/fiber-optic-

breakthrough-to-improve-internet-security-cheaply.html?_r=0

McCullagh, D. (2003, November 6). Start-up makes quantum leap into cryptography - CNET News. Technology News - CNET News. Retrieved December 11, 2012, from http://news.cnet.com/Start-up-makes-

quantum-leap-into-cryptography/2100-1029_3-5103373.html

Palmer, J. (2012, November 21). Quantum cryptography done on standard broadband fibre. BBC News, p. 1. Retrieved December 11, 2012, from www.bbc.co.uk/news/science-environment-13940928

Smith, T. (2004, May 14). Quantum Cryptography. UCSD - Department of Mathematics . Retrieved December 12, 2012, from http://math.ucsd.edu/~crypto/Projects/ToniSmith/crypto.html

Wickham, C. (2012, November 19). Unhackable telecom networks come a step closer. Chicago Tribune, p. 1. Retrieved December 11, 2012, from articles.chicagotribune.com/2012-11-19/business/sns-rt-us-science-

networks-hackingbre8aj00a-20121119_1_optical-fiber-quantum-cryptography-photons

Woodward, A. (2012, November 20). Quantum Cryptography at the End of Your Road | Guest Blog, Scientific American Blog Network. Scientific American Blog Network. Retrieved December 11, 2012, from http://blogs.scientificamerican.com/guest-blog/2012/11/20/quantum-cryptography-at-the-end-of-your-road/

REFERENCES