COUNTERPANE INTERNET SECURITY, INC. COMPLEMENTS ITS MANAGED SECURITY MONITORING SERVICES OFFERING THROUGH ITS ACQUISITION OF SECURITY DESIGN INTERNATIONAL, INC.

Consulting services give Counterpane customers added expert security advice

Cupertino, CA, April 23, 2001 -- Counterpane Internet Security, Inc., developer and leading provider of Managed Security Monitoring (MSM), today announced its acquisition of Security Design International, Inc. (SDI), a Virginia-based security consulting and services company that was a wholly-owned subsidiary of Cylink Corporation (NASDAQ: CYLK).

SDI has an international reputation for its expertise in vulnerability assessment, policy development and review, network design and review, and incident response services. The company will be fully integrated into Counterpane, remaining in its location near Counterpane's Secure Operations Center in Virginia. The purchase responds to the requests of Counterpane's customers for services that round out the company's Managed Security Monitoring.

"We'll be assisting customers in assessing their current security posture and processes to leverage the full value of our monitoring service," says Don Hewitt, Vice President, Counterpane Professional Services (previously President of Security Design International, Inc.) "Customers will also be able to receive regular consultative security reviews of their monitored networks. We'll suggest improvements based not only on our knowledge of existing vulnerabilities, but also on the reality of the events we see on the client's network."

"This new set of services will enable Counterpane to better match the unique environments faced in each customer network," says Tom Rowley, President and CEO of Counterpane Internet Security, Inc. "SDI consultants have provided services to some of the world's largest companies in telecommunications, pharmaceuticals, manufacturing, banking, and a variety of other industries. Our philosophy is to assist enterprise managers in creating business environments that reduce the risk of doing business electronically while capitalizing on the opportunities that Internet-based businesses provide."

"Cylink's divestiture of SDI is a vital step as we narrow our strategic focus to our high-performance wide area network, VPN and PKI solutions," said William P. Crowell, president and CEO of Cylink. "Now we will be able to devote our full efforts to our core business -- providing some of the industry's finest network security solutions -- and better leverage our strengths to serve the security market."

About Counterpane

Counterpane Internet Security, Inc. is the developer and leading provider of Managed Security Monitoring. Established in 1999 by entrepreneurial expert Tom Rowley and security technologist and author Bruce Schneier, Counterpane addresses the critical need for increased levels of security services. Centered around a network of sophisticated Secure Operations Centers, staffed by expert security analysts, the Company provides 24x7 monitoring, as well as penetration detection, and response. Counterpane's Managed Security Monitoring services enable e-business to be conducted safely. The company is funded by Accel Partners, Amerindo Investment Advisors, Inc., Bessemer Venture Partners, Dell, Deutsche Bank, Goldman Sachs, and Morgan Stanley Dean Witter Equity Fund. Headquarters are located at 1090 La Avenida, Mountain View, California, USA. Phone: 650-404-2400, Fax: 650-903-0461, Website: www.counterpane.com.

About Cylink Corporation

Cylink Corporation develops, markets and supports a comprehensive family of e-business security solutions. Founded in 1983, the company was the first to market security solutions that protect communications with public key cryptography. Cylink and its wholly owned subsidiaries serve Fortune 500 companies, multinational financial institutions, and government agencies worldwide. To contact Cylink, call (408) 855-6000 or visit www.cylink.com.

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Counterpane is a trademark of Counterpane Internet Security, Inc. All other companies, brands names or products are trademarks or registered trademarks of their respective companies.

Statements regarding the effect of the divestiture on Cylink's future economic performance are forward looking statements, involving risks and uncertainties. Factors that could cause actual results to differ from Cylink's expectations include continued weakening of markets, competitive pressures, and other risk factors listed in Cylink's Form 10-K.