Subject: Re: Git Privacy

From: "nick" <[email-masked]>
Date: Mon, 17 Jul 2023 04:20:12 +0000

Jason Pyeron wrote:
> > nick wrote:
> > Come to think of it, even if timezones were converted to UTC by default,
> > time of day would still leak information about a user's likely timezone.
>
> Discussed this with our policy wonks...
>
> Short answer - no. There is no legal assumption that can be made - your
> work hours cannot be assumed to be 9-5. They also said that time zone is
> "too broad at 1/24th of the world", but understood the concern.

An adversary may have other information which can be correlated with the
timestamps or timezone, making them less benign than in isolation.

> That being said the recommendation is to add --privacy

I'm not familiar with the processes here. Is it my responsibility to
implement it since I proposed it or who shall implement it?

> Where it assumes some defaults and those defaults can be controlled in
> your config or via --privacy=option1,option2
>
> And then some of the options can be:
>
> date-timezone=UTC
>
> date-precision=8hour

This sounds great. A few preliminary ideas on implementation:

'date-precision' must round the author AND committer timestamps
otherwise it's useless

'date-precision' must round down, never into the future

'date-timezone' must convert the date from local time and not just
replace the timezone

Any thoughts on making 'date-precision' also apply to GnuPG signature
timestamps? It's possible to specify a custom GnuPG command which does
this using gpg.program, but it's inconvenient. The relevant GnuPG option
is '--faked-system-time <epoch>!'

If that idea is no good, there should at least be a warning displayed
when the user signs anything with GnuPG with 'date-precision' enabled.

If that idea is good, then there should be a conditional check that the
rounding performed by 'date-precision' does not round down to before the
signing key was generated. Otherwise the signature will be invalid.