Secure Network Time Protocol (stime)

Last Modified: 2004-11-11


Tim Polk <>
Patrick Cain <>

Security Area Director(s):

Russell Housley <>
Sam Hartman <>

Security Area Advisor:

Russell Housley <>

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Description of Working Group:

For trust models to be truly portable across the Internet, transactions
must be anchored so they are comparable.  The one shared commodity that
can be widely agreed upon is time, and the ability to authenticate the
source of the time can assist in providing such portability in trust.
The ability to securely obtain time from authenticated sources is
thus becoming a key factor in security and non-repudiation.

Current IETF protocols address the distribution of time, and there
is also a project for the generation of cryptographically protected
timestamps.  Existing approaches to distributing time are vulnerable
to external attack and tampering, as these do not take advantage of
advances in public key infrastructure and cryptographic methods, and
require distribution of cryptographic keys via nonscalable out-of-band
means.  Securing time distribution using PKI mechanisms allows the
process to scale and minimizes risk.

The purpose of this working group is to define the message formats
and protocols - specifically, modifications to the existing Network
Time Protocol (NTP) - which are necessary to support the authenticated
distribution of time for the Internet.  The working group will be
chartered for a period of 12 months to meet this goal.  Utilization
of previous research in this area is expected.

Work will concentrate on the Internet-based NTP, to be enhanced with
addition of public-key based authentication and security.  The working
group expects to enhance NTP by way of occasional "setup" interchanges
between client and time server to establish a shared secret, followed
by normal NTP interchanges secured via the shared secret.  The output
of the working group is expected to be a standards-track document.

Goals and Milestones:

Done    Submit 3rd draft of Authentication Scheme Extensions to NTP as an I-D
Done    Submit 4th draft of Authentication Scheme Extensions to NTP as an I-D
Jul 01    Submit Authentication Scheme Extensions to NTP to IESG for consideration as an RFC

No Current Internet-Drafts

No Request For Comments