What's a "quantum repeater" in this context? As for "Hype Watch", I tend to agree, but I also believe that Gelfond (who I spoke to last year) actually does have a 'viable' system. Commerically viable is another thing entirely, however. -TD

From: "R. A. Hettinga" <rah@shipwright.com> To: cryptography@metzdowd.com, cypherpunks@al-qaeda.net Subject: QC Hype Watch: Quantum cryptography gets practical Date: Thu, 30 Sep 2004 17:39:24 -0400

<http://www.computerworld.com/printthis/2004/0,4814,96111,00.html>

- Computerworld

Quantum cryptography gets practical

Opinion by Bob Gelfond, MagiQ Technologies Inc.

SEPTEMBER 30, 2004 (COMPUTERWORLD) - In theory and in labs, quantum cryptography -- cryptography based on the laws of physics rather than traditional, computational difficulty -- has been around for years. Advancements in science and in the world's telecommunications infrastructure, however, have led to the commercialization of this technology and its practical application in industries where high-value assets must be secure.

Protecting information today usually involves the use of a cryptographic protocol where sensitive information is encrypted into a form that would be unreadable by anyone without a "key." For this system to work effectively, the key must be absolutely random and kept secret from everyone except the communicating parties. It must also be refreshed regularly to keep the communications channel safe. The challenge resides in the techniques used for the encryption and distribution of this key to its intended parties to avoid any interception of the key or any eavesdropping by a third party.

Many organizations are advancing quantum technology and bringing it outside academia. Research labs, private companies, international alliances such as the European Union and agencies such as the Defense Advanced Research Projects Agency are investing tens of millions of dollars in quantum research, with projects specifically focused on the challenge of key distribution.

The trouble with key distribution

Huge investment in the late 1990s through 2001 created a vast telecommunications infrastructure resulting in millions of miles of optical fiber laid across the country and throughout buildings to enable high-speed communications. This revolution combined a heavy reliance on fiber-optic infrastructure with the use of open network protocols such as Ethernet and IP to help systems communicate.

Although this investment delivers increased productivity, dependence on optical fiber compounds key distribution challenges because of the relative ease with which optical taps can be used. With thousands of photons representing each bit of data traveling over fiber, nonintrusive, low-cost optical taps placed anywhere along the fiber can siphon off enough data without degrading the signal to cause a security breach. The threat profile is particularly high where clusters of telecommunications gear are found in closets, the basements of parking garages or central offices. Data can be tapped through monitoring jacks on this equipment with inexpensive handheld devices. This enables data to be compromised without eavesdroppers disclosing themselves to the communicating parties.

Another important aspect of this problem is the refresh rate of the keys. Taking large systems off-line to refresh keys can cause considerable headaches, such as halting business operations and creating other security threats. Therefore, many traditional key-distribution systems refresh keys less than once per year. Infrequent key refreshing is detrimental to the security of a system because it makes brute-force attacks much easier and can thereby provide an eavesdropper with full access to encrypted information until the compromised key is refreshed.

Adding quantum physics to the key distribution equation

Companies are now in a position to use advancements in quantum cryptography, such as quantum key distribution (QKD) systems, to secure their most valued information. Two factors have made this possible: the vast stretches of optical fiber (lit and dark) laid in metropolitan areas, and the decreasing cost in recent years of components necessary for producing QKD systems as a result of the over-investment in telecommunications during the early 2000s.

Based on the laws of quantum mechanics, the keys generated and disseminated using QKD systems have proved to be absolutely random and secure. Keys are encoded on a photon-by-photon basis, and quantum mechanics guarantees that the act of an eavesdropper intercepting a photon will irretrievably change the information encoded on that photon. Therefore, the eavesdropper can't copy or read the photon -- or the information encoded on it -- without modifying it, which makes it possible to detect the security breach. In addition to mitigating the threat of optical taps, QKD systems are able to refresh keys at a rate of up to 10 times per second, further increasing the level of security of the encrypted data.

Not for everyone

Quantum key distribution systems aren't intended for everyday use: You won't find a QKD system in the home office anytime soon. One reason is that a QKD system requires a dedicated fiber-optic line. Also, because the loss of photons over longer distances, these systems have current distance limitations of approximately 120 kilometers (nearly 75 miles) which is common with optical infrastructure equipment. Quantum repeaters are under development to extend that range much farther. Finally, the end points of these QKD systems must reside in secure locations. However, since they are tamper-proof, if attempts are made to compromise them, they will stop running or fire off an alarm, thus ensuring ultimate information protection.

The practical development of QKD systems has made them applicable for a number of industries such as financial services, biotech and telecommunications along with government sectors such as intelligence and the military. They don't require a physicist or an engineer to administer them. These appliances fit in standard racks, plug into existing networks, and are reliable around the clock. QKD systems interoperate with security standards such as IPsec-based VPNs providing an added layer of security to networks.

Ask the right questions

As you look for better ways to protect your company's most important information, QKD may be an option. However, be sure you understand the strengths and drawbacks of quantum key distribution by asking the right questions:

1. What does your organization's security policy say about the threat profile for high-value assets?

2. How frequently are your encryption keys changed and by what method?

3. What is the total cost of ownership for QKD products? Are there additional costs in support and training?

4. Are your competitors implementing QKD systems?

5. What infrastructure requirements must be met?

6. What personnel/staffing levels are required?

7. How does this QKD system work with existing cryptography systems?

8. What are the distance limitations of this system?

QKD isn't an everyday desktop tool, but the technology makes sense for those organizations that have the resources and the capacity to use it effectively.

Bob Gelfond is founder and CEO of MagiQ Technologies Inc., a vendor of quantum information processing services and products in New York.

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