'Gold codes' developer touts wireless security scheme

Loring Wirbel
Oct 21, 2004
URL: http://www.commsdesign.com/showArticle.jhtml?articleID=51000037

COLORADO SPRINGS, Colo. The developer of the pseudorandom "Gold codes" used in digital cellular networks and the Global Positioning System has demonstrated a self-synchronized receiver technology for enhancing security in wireless LANs, cellular networks and ultrawideband systems.

Robert Gold Comm Systems Inc. (Carlsbad, Calif.) has demonstrated a two-receiver system to the U.S. Air Force, and is licensing its software code to chip makers.

Gold is well known in the RF and DSP algorithm communities for his work in the 1980s on an algorithm that uses sequences of pseudorandom numbers easily generated with two feedback shift registers. The so-called "Gold codes" provide auto- and cross-correlation for wireless networks, and were used in early wireless radio networks and in the GPS satellite system.

The current work stems from a U.S. Air Force contract to explore ways of improving the security of spread-spectrum systems, including direct-sequence or frequency-hopping systems. In both types, information about the synchronization pattern used for spreading a signal must be sent to receivers in the clear, compromising basic system security.

Gold said he has proposed development of an efficient module of embedded software for transmitters and receivers that allow them to synchronize patterns without using external clocks. Network nodes can be synchronized in milliseconds, Gold said. Software for the self-synchronizer occupies only 7,000 lines of code in a Windows environment, and can compressed even more when compiled for embedded environments.

"It represents very little overhead, even in constrained environments like handsets," Gold said.

Gold's company completed a phase-one study under the Air Force's Small Business Innovative Research program, and has delivered a two-receiver frequency-hopping test bed to the Air Force. The contract was not related to a specific platform, Gold said, but was conducted as a basic research program under the RF sensor division of the Electronic Warfare Technology Branch at Wright-Patterson Air Force Base (Dayton, Ohio).

The algorithm has several properties useful for ad-hoc WiFi radio networks as well as for police and fire radios on virtual private networks. Secure communications are possible without using encryption, though the new receiver software can be used in conjunction with either private- or public-key encryption.

Receivers can be addressed individually or in selected groups, allowing the use of IP broadcast and multicast methods. A receiver also can enter and leave the network at any time, and a transmitter will securely confirm group membership. The last two factors could be of particular interest in emerging Voice-over-IP networks that span LANs and WANs, Gold said.

While the Air Force is exploring a range of and classified and unclassified applications for the technology, Gold's company is free to license the basic algorithms for commercial applications.

Gold said he has assembled a hardware and software implementation team, thereby making the startup more than a licensing clearinghouse. But Gold added that the company has no intention of moving directly into volume production of hardware systems.

Instead, the company will explore a range of licensing opportunities with OEMs, embedded software firms and chip manufacturers, though Gold said the software's most logical point for integration is at the single-chip level.

More information on terms is available at the company's Web site.

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