Cable generally more secure than telephone modem

Unlike the telephone network that gives users dedicated connectivity, the cable network uses a broadcast architecture. So, if you share bandwidth with your neighbors, can’t they read your e-mail?

“Nothing is 100 percent secure,´ said Luisa Murcia, vice president of technology for the TCI Advanced Products Group. “But a cable modem is more secure than a telephone modem because the DOCSIS (Data Over Cable Service Interface Specification) standard has both encryption and security hard-wired into the chip set.”

DOCSIS 1.0, which specifies “best effort” data services, employs so-called “Baseline Privacy” that uses RSA, a well-known key exchange encryption algorithm.

The next version, DOCSIS 1.1, will offer additional capabilities for tier services, Murcia said. Voice over cable is problematic, for example, because the nature of packetized data leaves it susceptible to delay and “jitter,” which is unacceptable for most conversations. Therefore DOCSIS 1.1 will have quality of service, or QOS, options for voice. Since there’s than one service to protect, it also will have “Baseline Privacy Plus,” an additional level of encryption.

Although removable smart cards were under consideration as another layer of security, they didn’t make it into the DOCSIS specification. “Part of the problem with security is the balance between cost and what you’re trying to protect,” Murcia explained. “The additional cost of putting a smart card into your modem wasn’t justified. We’re trying to keep the cost low for the consumer.”

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