Re: [PATCH 0/1] Hashed mailmap support

[Jeff King <peff@peff.net>]

On Sun, Dec 13, 2020 at 01:05:38AM +0000, brian m. carlson wrote:

> Note that this is not perfect, because a user can simply look up all the
> hashed values and find out the old values.  However, for projects which
> wish to adopt the feature, it can be somewhat effective to hash all
> existing mailmap entries and include some no-op entries from other
> contributors as well, so as to make this process less convenient.

I remain unconvinced of the value of any noop entries. Ultimately it's
easy to invert a one-way hash that comes from a small known set of
inputs. And that's true whether there are extra noops or not.

The interesting argument IMHO is that somebody has to _bother_ to invert
the hash. So it means that the old and new identities do not show up
next to each other in a file indexed by search engines, etc. That drops
the low-hanging fruit.

And from that argument, I think the obvious question becomes: is it
worth using a real one-way function, as opposed to just obscuring the
raw bytes (which Ævar went into in more detail). I don't have a strong
opinion either way (the obvious one in favor is that it's less expensive
to do so; and something like "git log" will have to either compute a lot
of these hashes, or cache the hash computations internally).

I think somebody also mentioned that there's value in the social
signaling here, and I agree with that. But that is true even for a
reversible encoding, I think.

-Peff