5 ms·

Infosec slant: such investigations are made way easier by precise timestamping (everything happens in a few milliseconds), but the source of truth (GPS or other

by brohee 6y ago

Infosec slant: such investigations are made way easier by precise timestamping (everything happens in a few milliseconds), but the source of truth (GPS or other GNSS) is usually pretty easily spoofable if you only intend to move the time a few milliseconds. Galileo has a project addressing this (https://ec.europa.eu/transparency/regexpert/?do=groupDetail.groupMeetingDoc&docid=36951 https://ec.europa.eu/transparency/regexpert/?do=groupDetail....) but AFAIK it's not in the signal yet. And once it is, it will take years for the devices doing the satellite time to PTP to be replaced/updated.

traceroute66 6y ago
Surely this is only true to a minimal extent in world where you can already buy timeservers that support multiple independent time sources out of the box (multiple satellite Galileo,GPS etc. + terrestrial radio e.g. DCF77). IIRC if you're dead serious and money is no object, all the major national time labs also allow you to run a private leased line to their facility for direct checks.
- brohee 6y ago
  As of now all GNSS constellation are somewhat spoofable, especially if you only want to drift a clock a few milliseconds late... And a lot of timeservers are still GPS only so the attack is pretty easy to perform. The private line idea is maybe doable (but which protocol? NTP doesn't offer the needed precision), but as all substations would need one, my guess is that eventually money would be an object...
  - michaelt 6y ago
    > (but which protocol? NTP doesn't offer the needed precision) You might enjoy reading the documentation for NPLTime [1] which uses PTP over telecom fibre networks. Of course, their target market is banks with record keeping requirements so it probably costs a fortune. [1] https://www.npl.co.uk/npltime https://www.npl.co.uk/npltime

5 ms·

Infosec slant: such investigations are made way easier by precise timestamping (everything happens in a few milliseconds), but the source of truth (GPS or other

by brohee 6y ago

traceroute66 6y ago
Surely this is only true to a minimal extent in world where you can already buy timeservers that support multiple independent time sources out of the box (multiple satellite Galileo,GPS etc. + terrestrial radio e.g. DCF77). IIRC if you're dead serious and money is no object, all the major national time labs also allow you to run a private leased line to their facility for direct checks.
- brohee 6y ago
  As of now all GNSS constellation are somewhat spoofable, especially if you only want to drift a clock a few milliseconds late... And a lot of timeservers are still GPS only so the attack is pretty easy to perform. The private line idea is maybe doable (but which protocol? NTP doesn't offer the needed precision), but as all substations would need one, my guess is that eventually money would be an object...
  - michaelt 6y ago
    > (but which protocol? NTP doesn't offer the needed precision) You might enjoy reading the documentation for NPLTime [1] which uses PTP over telecom fibre networks. Of course, their target market is banks with record keeping requirements so it probably costs a fortune. [1] https://www.npl.co.uk/npltime https://www.npl.co.uk/npltime