Recent attacks against several Internet sites engaged in electronic commerce have raised concerns about the security of the NIST time servers and the authenticity of the messages they transmit. Although improving the security of the time servers is primarily an internal matter which has little or no impact outside of NIST, the needs for authentication and certification of our time signals has led us to consider new types of services.

Clients who use our services (especially those who are engaged in electronic commerce) have two concerns: (1) that the time messages that they receive from our servers really came from NIST and not from some third-party attempting to spoof our system and (2) that the client software provide an audit trail that can be used to verify compliance with legal requirements. An example of the latter is the requirement by the National Association of Securities Dealers that members use time stamps traceable to NIST with an uncertainty of less than 3 seconds.

There is no simple method that can address all of the potential problems. In particular, denial-of-service attacks can be particularly troublesome. Although it would be difficult to mount such an attack against the entire ensemble of NIST time servers (because they are not located at the same place), an attack against a single server or against a single client is much more difficult to deal with.

We are evaluating a number of strategies to address these concerns. Some of this work is in collaboration with private companies through Cooperative Research and Development Agreements (CRADA) and also in collaboration with other groups at NIST.

For questions or more information contact time@time.nist.gov.