Git records the local timezone when a commit is made [1]. Knowledge of the timezone in which a commit was made could be used as a bit of identifying information to de-anonymize the committer.

Setting one’s timezone to UTC can help mitigate this issue [2][3] (though, ofc, one must still be wary of time-of-day commit patterns being used to deduce a timezone).

References
  1. Git documentation. git-commit. “Date Formats: Git internal format”. Accessed: 2024-08-31T07:52Z. https://git-scm.com/docs/git-commit#Documentation/git-commit.txt-Gitinternalformat.

    It is <unix-timestamp> <time-zone-offset>, where <unix-timestamp> is the number of seconds since the UNIX epoch. <time-zone-offset> is a positive or negative offset from UTC. For example CET (which is 1 hour ahead of UTC) is +0100.

  2. jthill. “How can I ignore committing timezone information in my commit?”. Stack Overflow. Published: 2014-05-26T16:57:37Z. (Accessed: 2024-08-31T08:27Z). https://stackoverflow.com/questions/23874208/how-can-i-ignore-committing-timezone-information-in-my-commit#comment36750060_23874208.

    to set the timezone for a specific command, say e.g. TZ=UTC git commit

  3. Oliver. “How can I ignore committing timezone information in my commit?”. Stack Overflow. Published: 2022-05-22T08:56:38Z (Accessed: 2024-08-31T08:30Z). https://stackoverflow.com/a/72336094/7934600

    each commit Git stores a author date and a commit date. So you have to omit the timezone for both dates.

    I solved this for my self with the help of the following Git alias:

    [alias]
co = "!f() { \
    export GIT_AUTHOR_DATE=\"$(date -u +%Y-%m-%dT%H:%M:%S%z)\"; \
    export GIT_COMMITTER_DATE=\"$(date -u +%Y-%m-%dT%H:%M:%S%z)\"; \
    git commit $@; \
    git log -n 1 --pretty=\"Autor: %an <%ae> (%ai)\"; \
    git log -n 1 --pretty=\"Committer: %cn <%ce> (%ci)\"; \
}; f"

Cross-posts:

  • ExtremeDullard@lemmy.sdf.org
    26·
    2 months ago

    It’s not the only thing that leaks timezone data, and the fix is identical: have the machine pretend you’re in UTC.

    For example: if you enable Resist Fingerprinting (RFP) in Librewolf, it will lie to websites and pretend your timezone is UTC - because of course timezone is one of the factors used to fingerprint you - and all the sites you visit that show you your local time, or depend on your local time for something or other, will show you the wrong time. And that’s how you know it works 🙂

    • Kalcifer@sh.itjust.worksOPEnglish
      2·
      2 months ago

      have the machine pretend you’re in UTC.

      That is a possible solution, though not exactly the most convenient, imo. That is, if I understand you correctly that you are talking about setting the OS timezone to be UTC.

    • viking@infosec.pub
      34·
      2 months ago

      And that’s the reason why I don’t use it, I need specific websites that access my local time, and apparently whitelisting is not a thing.