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sdwdate - Secure Distributed Web Date - Homepage

Time keeping is crucial for security, privacy, and anonymity. Sdwdate is a Tor friendly replacement for rdate and ntpdate that sets the system's clock by communicating via onion end-to-end encrypted TCP with Tor onion webservers. Time providers are exclusively reputable sources (whistle-blowing and privacy friendly onion sites) that are highly likely to be hosted on different hardware.

At randomized intervals, sdwdate connects to a variety of webservers and extracts the time stamps from http headers (RFC 2616).

Comparison of sdwdate and ntp

sdwdate ntp
written in memory-save language Yes No
distributed trust Yes No
secure connection by default (authentication and encryption) Yes No
gradual clock adjustments Yes Yes
daemon Yes Yes
works over Tor Yes No [1]
does not require Tor No Yes
client, time fetcher Yes Yes
server, time provider No, not yet Yes
Apparmor profile Yes Yes
drop in config folder Yes No
proxy support Yes No [2] [3]
can be secured by default on linux distribution level Yes No [4]
secure Yes No [5]
optional gui Yes, sdwdate-gui (a systray icon) No

See also:


  • server, time provider
  • sdwdate issue tracker:



  1. Requires UDP which is unsupported by Tor, see Tor#UDP.
  2. http://lists.ntp.org/pipermail/questions/2007-October/015754.html
  3. http://linux.derkeiler.com/Mailing-Lists/Debian/2003-07/0361.html
  4. NTP security vulnerability because not using authentication by default
  5. See Dev/TimeSync#NTP.

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