Quantum key distribution

Tyler Durden camera_lumina at hotmail.com
Wed Dec 1 09:52:21 PST 2004


"Andrew Hammond, a vice president of
MagiQ, estimates that the market for QKD systems will reach $200 million
within a few years, and one day could hit $1 billion annually."

What an idiot. OK, it's basically a marketing guy's job to make up all kinds 
of BS, but any reasonably comptetant marketing guy knows to make up BS that 
someone will actually BELIEVE.

-TD


>From: "R.A. Hettinga" <rah at shipwright.com>
>To: cryptography at metzdowd.com, cypherpunks at al-qaeda.net
>Subject: Quantum key distribution
>Date: Wed, 1 Dec 2004 12:29:31 -0500
>
><http://www.aip.org/tip/INPHFA/vol-10/iss-6/p22.html>
>   - The Industrial Physicist
>
>?Quantum key distribution
>
>Data carrying photons may be transmitted by laser and detected in such a
>way that any interference will be noted
>
>by Jennifer Ouellette
>
>pdf version of this article
>
>Computing's exponential increase in power requires setting the bar always
>higher to secure electronicdata transmissions from would-be hackers. The
>ideal solution would transmit data in quantum bits, but truly quantum
>information processing may lie decades away. Therefore, several companies
>have focused on bringing one aspect of quantum communications to market-
>quantum key distribution (QKD), used to exchange secret keys that protect
>data during transmission. Two companies, MagiQ Technologies (New York, NY)
>and ID Quantique (Geneva, Switzerland), have released commercial QKD
>systems, and several others plan to enter the marketplace within two years.
>Figure 1. When blue light is pumped into a nonlinear crystal, entangled
>photon pairs (imaged here as a red beam with the aid of a diode laser)
>emerge at an angle of 30 to the blue beam, and the beams are sent into
>single-mode fibers to be detected. Because the entangled photons "know"
>each other, any interference will result in a mismatch when the two beams
>are compared. (University of Vienna/Volker Steger)
>
>  "There is a continuous war between code makers and code breakers," says
>Alexei Trifonov, chief scientist with MagiQ. Cryptologists devise more
>difficult coding schemes, only to have them broken. Quantum cryptography
>has the potential to end that cycle. This is important to national security
>and modern electronic business transactions, which transmit credit card
>numbers and other sensitive information in encrypted form. The Department
>of Defense (DoD) currently funds several quantum-cryptography projects as
>part of a $20.6 million initiative in quantum information. Globally, public
>and private sources will fund about $50 million in quantum-cryptography
>work over the next several years. Andrew Hammond, a vice president of
>MagiQ, estimates that the market for QKD systems will reach $200 million
>within a few years, and one day could hit $1 billion annually.
>
>Key types
>
>QKD was proposed roughly 20 years ago, but its premise rests on the
>formulation of Heisenberg's uncertainty principle in 1927. The very act of
>observing or measuring a particle-such as a photon in a data stream-changes
>its behavior (Figure 1). Any moving photon can have one of four
>orientations: vertical, horizontal, or diagonal in either direction. A
>standard laser can be modified to emit single photons, each with a
>particular orientation. Would-be hackers (eavesdroppers in cryptography
>parlance) can record the orientations with photon detectors, but doing so
>changes the orientation of some photons-and, thus, alerts the sender and
>receiver of a compromised transmission.
>
>An encryption key-the code needed to encrypt or decipher a message-consists
>of a string of random bits.  Such a key is useless unless it is completely
>random, known only to the communicating parties, and changed regularly. In
>the one-time-pad approach, the key length must equal the message length,
>and it should be used only once. In theory, this makes the encrypted
>message secure, but problems arise in practice. In the real world, keys
>must be exchanged by a CD-ROM or some other physical means, which makes
>keys susceptible to interception. Reusing a key gives code breakers the
>opportunity to find patterns in the encrypted data that might reveal the
>key. Historically, the Soviet Union's accidental duplication of
>one-time-pad pages allowed U.S. cryptanalysts to unmask the spy Klaus Fuchs
>in 1949.
>
>Rather than one-time-pad keys, many data-transmission security systems
>today use public-key cryptography, which relies on very long prime numbers
>to transmit keys. A typical public-key encryption scheme uses two keys. The
>first is a public key, available to anyone with access to the global
>registry of public keys, and the message is encrypted with it. The second
>is private, accessible only to the receiver. Both keys are needed to
>unscramble a message. The system's primary weakness is that a powerful
>computer could use the public key to learn the private key (see The
>Industrial Physicist, August 2000, pp. 29-33).
>
>Quantum key distribution
>
>A key distributed using quantum cryptography would be almost impossible to
>steal because QKD systems continually and randomly generate new private
>keys that both parties share automatically. A compromised key in a QKD
>system can only decrypt a small amount of encoded information because the
>private key may be changed every second or even continuously. To build up a
>secret key from a stream of single photons, each photon is encoded with a
>bit value of 0 or 1, typically by a photon in some superposition state,
>such as polarization. These photons are emitted by a conventional laser as
>pulses of light so dim that most pulses do not emit a photon. This approach
>ensures that few pulses  contain more than one photon. Additional losses
>occur as photons travel through the fiber-optic line. In the end, only a
>small fraction  of the received pulses actually contain a photon. However,
>this low yield is not problematic for QKD because only photons that reach
>the receiver are used. The key is generally encoded in either the
>polarization or the relative phase of the photon (see "Keeping Alice and
>Bob secure", below).
>
>  The most common standard protocol for QKD is called BB84, after its
>inventors, IBM's Charles Bennett and Gilles Brassard. Invented in 1984, it
>uses a stream of single photons to transfer a cryptographic key between two
>parties, who can use it to encode and decode data transmitted using
>standard high-speed techniques. Right now, single photons allow real-time
>data transmissions only at low speed, typically 100 bits/s-a hundred
>millionth the speed of today's fastest fiber-optic transmission systems.
>That explains why most companies have focused on commercializing QKD and
>not on data encryption.
>Polarization-based encoding works best for free-space communication systems
>rather than fiber-optic lines. Data are transmitted faster in free-space
>systems, but they cannot traverse the longer distances of fiber-optic
>links. In July 2004, a team at the National Institute of Standards and
>Technology (NIST), working with Acadia Optronics (Rockville, MD),
>demonstrated the world's fastest quantum- cryptography system by sending a
>quantum key over a 730-m free-space link at rates of up to 1 megabit/s-
>1,000 times as fast as previously reported results. The NIST system uses an
>infrared laser to generate the photons and reflecting telescopes with 8-in.
>mirrors to send and receive the photons through air.
>
>NIST's system differs from other existing QKD systems in how it identifies
>a photon from the sender, as opposed to photons from another source, such
>as the sun. The scientists record the exact time of each emission and look
>for a photon only when one is expected. The window of observation time must
>be very short, but NIST physicist Joshua Bienfang says that making frequent
>brief observations enables the team to generate new keys more often.
>
>Fiber-optic links
>
>Randomly generated keys are changed up to 1,000 times/s in MagiQ's OPN
>Security Gateway, which uses a secure fiber-optic link to transmit the
>changing key sequence up to 120 km as a stream of polarized photons. The
>company claims that linking its systems together can transmit a QKD several
>hundred kilometers (Figures 2 and 3).
>Quantum properties other than polarization can encode the value of a bit
>for the quantum key, says Gregoire Ribordy, CEO of Swiss start-up ID
>Quantique. His company introduced the first commercial quantum-cryptography
>products in 2002: single-photon detectors and random-number generators, two
>essential components for quantum-cryptography systems. In 2003, the company
>partnered with two electronic-security firms to develop a commercial 
>system.
>Figure 3. A more detailed network shows routers for concentrating and
>directing Internet traffic, Sonet telecommunications protocol, wave
>division multiplexers, optical amplifiers, and repeaters.
>
>ID Quantique's system encodes data in the phase of the photon instead of
>its polarization state. An interferometer splits beams of light and then
>recombines them at the output end, and it can do the same with a single
>photon. Although a photon cannot split in two, its dual wave-particle
>nature allows it to travel through both arms of the interferometer as a
>wave, only becoming a particle again when it recombines and is detected at
>the output end. It takes but a slight change in the length of one
>interferometer arm to randomly alter a photon's phase.
>Figure 4. Henry Yeh, director of programs, and Chip Elliot, principal
>engineer, in the Quantum  Laboratory at BBN Technologies, which operates
>the DARPA-funded world's first quantum key distribution network. (BBN
>Technologies)
>
>  In 2002, scientists at Northwestern University developed a
>quantum-cryptography method capable of sending encr ypted data over a
>fiber- optic line at 250 megabits/s, almost 1,000 times as fast as prior
>quantum technology. The team used standard lasers and existing optical
>technology to transmit large bundles of photons; other techniques used in
>quantum cryptography rely on single photons, which are harder to detect.
>BBN Technologies (Cambridge, MA) operates the world's first quantum
>cryptographic network, which links several different kinds of QKD systems
>(Figure 4). Some use off-the-shelf optical lasers and detectors to emit and
>detect single photons; others use entangled pairs of photons.
>
>  This DARPA-funded network runs between BBN, Harvard, and Boston
>University, a citysized schematic designed to test the robustness of such
>systems in real-world applications (Figure 5). It allows multiple users at
>each organization to tap into a fiberoptic loop secured by a
>quantum-cryptography system. BBN will soon add a free-space QKD link and an
>entangled- photon QKD system.  Other companies are also investing in
>quantum-cryptography systems. IBM's Almaden Research Center, the NEC
>Research Institute, Toshiba, and Hewlett-Packard are on the brink of
>introducing products. In March 2004, NEC scientists in Japan sent a single
>photon over a 150-km fiber-optic link, breaking the transmissiondistance
>record for quantum cryptography.
>Figure 5. This network allows users at BBN Technologies, Harvard
>University, and Boston  University to tap into a fiber-optic loop secured
>by a quantum-cryptography  system. (BBN Technologies/Funding by the Defense
>Advanced Research Projects Agency)
>
>To date, most commercially viable QKD systems rely on fiber-optic links
>limited to 100 to 120 km. At longer distances, random noise degrades the
>photon stream. Quantum keys cannot travel far over fiberoptic lines, and,
>thus, they can work only between computers directly connected to each
>other. The only way to achieve such a system with total security in a
>networking environment and at greater distances is to add quantum
>repeaters-rudimentary quantum computers- to regenerate the bits. NEC and
>Hewlett- Packard are developing components needed to make quantum repeaters
>a reality.
>
>Entangled photons
>
>To date, physicists have not developed an ideal single-photon source. In a
>small number of instances, more than one photon is emitted, making the
>system vulnerable. A hacker could tap the system and measure one of the
>photons to discover what polarization the sender is using, and then send
>the other onto the receiver-all without revealing his or her presence.
>
>That explains why entangled photons present an attractive future option.
>When two photons become entangled, if one is vertically polarized, the
>other is always polarized horizontally. The polarization of a single photon
>cannot be known until it is measured, and the measurement will
>automatically determine the polarization of the other photon, even if it is
>several hundred meters away. Albert Einstein dubbed this "spooky action at
>a distance." A QKD system using entangled photons would have a critical
>advantage: the key comes into existence simultaneously at both sender and
>receiver nodes, eliminating the possibility of interception.
>
>Entangled-state quantum cryptography works by generating entangled-photon
>pairs and distributing them through fibers or free space so that each
>arrives at the receiver's detectors simultaneously. Once measured, the
>photons assume one of four polarization states at random. Entanglement
>works over fiberoptic lines, but there are inevitable losses, which limits
>transmission distance. Free-space techniques extend the entanglement to
>distances in the range of 24 km.
>
>Last April, a team from the University of Vienna, Austria's ARC Seibersdorf
>Research (Seibersdorf), and Ludwig- Maximilians University (Munich,
>Germany) performed the first quantum-secured transfer of money using
>entangled photons. The scientists installed a 1.45-km fiber-optic line
>under Vienna's streets to link a transmitter at city hall to a receiver at
>the headquarters of an Austrian bank. They used a crystal with nonlinear
>optical properties to split photons with wavelengths of 405 nm into
>entangled pairs of photons with wavelengths of 810 nm. Using the key, the
>team safely transferred funds from city hall to the bank.
>
>In April 2004, the European Union launched the SECOQC project, which
>involves 41 participants from 12 countries: Austria, Belgium, Canada, the
>Czech Republic, Denmark, France, Germany, Italy, Russia, Sweden,
>Switzerland, and the United Kingdom. Participants have pledged 11.4 million
>euro ($14.8 million U.S.) in funding over the next four years to create a
>secure quantum network globally. One of the project's eight goals is to
>develop a suitable QKD system. The techniques under consideration are the
>University of Vienna's entangledphoton scheme, ID Quantique's attenuated
>pulsed-laser source of single photons, and free-space links. The last would
>also enable key distribution using modulated coherent states rather than
>photon counting.
>
>Faster detectors
>
>Future developments will focus on faster photon detectors, a major factor
>limiting the development of practical systems for widespread commercial
>use. Chip Elliott, BBN's principal engineer, says the company is working
>with the University of Rochester and NIST's Boulder Laboratories in
>Colorado to develop practical superconducting photon detectors based on
>niobium nitride, which would operate at 4 K and 10 GHz. Laboratory models
>can already detect billions of photons per second-several hundred orders of
>magnitude faster than today's commercial photon detectors.
>
>The ultimate goal is to make QKD more reliable, integrate it with today's
>telecommunications infrastructure, and increase the transmission distance
>and rate of key generation. "It's one thing to achieve quantum cryptography
>in the laboratory on a multimillion dollar government- funded project,"
>says MagiQ's Trifonov. "It's quite another to make it reasonably
>cost-effective for commercial applications."
>
>
>
>--
>-----------------
>R. A. Hettinga <mailto: rah at ibuc.com>
>The Internet Bearer Underwriting Corporation <http://www.ibuc.com/>
>44 Farquhar Street, Boston, MA 02131 USA
>"... however it may deserve respect for its usefulness and antiquity,
>[predicting the end of the world] has not been found agreeable to
>experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'





More information about the cypherpunks-legacy mailing list