How to use git rebase to edit both author/committer and timestamps at the same time?

I've been trying to rewrite the history of a Git repository to consolidate commits, remove large files, and many other changes. git filter-branch is not recommended as a tool and I want the precision of rewriting the history manually.

I've run into a major obstacle. When I rewrite the commits, the rewritten commits show up as being committed by me (author authored and I committed), which I don't want.

I am able to get around this by running git config user.name and git config user.email before picking each commit in rebase. This makes it look like the original author committed it.

So far so good, but when I do this the committer timestamp is invariably "now". I can change the author timestamp with git commit --amend --date, but the committer timestamp is unchangeable.

I can use the option --committer-date-is-author-date, and that works (although it changes the timezone, which I don't like)...but seemingly not with an interactive rebase, where it does nothing. The automatic rebase does not permit me to use git config user.name/email to make the original author of the commit show up by themselves.

I have tried using set GIT_COMMITTER_DATE= followed by git commit --amend --no-edit. It was working at first, but then suddenly stopped working for an unknown reason. It simply does nothing now - the committer timestamp isn't affected.

This leaves me with a choice of having me added to the commits as the committer, or having an inaccurate timestamp of "now" in a project with years of history.

I'm looking for a way so that people looking at the history can see the original author and the original timestamp (or whatever ones I specify), and that is compatible with interactive rebase because I'm going to be doing a lot of rebasing, so the entire history will be rewritten from further and further in the past.

Yeah, this might be a crazy project, but does anyone have any suggestions on how to accomplish this?

(Yes, I am doing this on a separate branch. I will force push to the main branch after I have finished the project.)

EDIT: This is what happens when I try to set the environment variables as part of the rebase: https://gyazo.com/d6189169809023e2b722fedc03169011

(Using the following input: https://gyazo.com/8a38c243dac215c4a333394ef8fae78e)

I can set the environment variables using CMD, but Git can't do it: https://gyazo.com/39644a586b78cb933988e90880c67286

I am using Windows 10 Home Edition.

According to the documentation git commit recognizes the following environment variables

GIT_AUTHOR_NAME
GIT_AUTHOR_EMAIL
GIT_AUTHOR_DATE
GIT_COMMITTER_NAME
GIT_COMMITTER_EMAIL
GIT_COMMITTER_DATE

Their values take precedence over the configuration values.

So in your case you need to set the GIT_COMMITTER_* variables.

You can check if git recognizes the variables by using the command

git var GIT_COMMITTER_IDENT

If it does not recognize them, make sure you are actually setting them. Setting and reading environment variables is OS dependent and can be tricky.