Committing code is not like browsing facebook, or searching on google. Even then, your name is on any posts you're making on twitter or facebook, and i'm sure google knows what you're searching.
As a maintainer, why would you want people to be able to deny making a given commit? or have them come in completely anonymously?
As a user of code published on Github, I sure as heck want there to be clear ownership and authorship of the code I use, and to be able to hold them accountable for malice. And there is lots malicious code on Github, trying to disguise itself as legit; Having a strong public persona isn't guarantee that my github code isn't malicious, but it does raise the stakes.
As a human who has seen what happens when people commit mistakes, we're very emotionally bad at dealing with mistakes. "Who broke the vase?" is a tough question to ask. "Who broke the build" can carry the same weight - Both very little, and very much, depending on when it's asked and how expensive the vase was. I'd like to think that making mistakes will be easier in a merkle-tree structured world; That as a collective, we will learn to do a better job of helping people admit their mistakes, come forward with them, and say "I made that mistake, and have learned from it". The internet has proven that false again and again.
In two important ways - People are unwilling to forgive, and people are unwilling to admit. Past minor mistakes haunt people forever all the time. Look at things like "Has Justine Landed Yet?"[1].
A malicious liar (We'll call them Eve) will deny, refute, and plain old lie in the face of whatever. There can be incredibly convincing evidence (A RSA-Key Verified Git Signature, for example) of... whatever, and it will be written off as "Harassment" by friends of Eve. Further: There's plenty of actual malice that passes itself off as not. Rapists say "She clearly wanted it, she got wet" - Criminals do that at all levels, making up excuses for why their victims deserved it.
Regardless - It is a sea change to be held accountable for your code. I do want it, but I do not believe that SSH key verification will achieve that. I think it will be a significant change when it does happen, though, and one with significant consequences.
[1]https://www.nytimes.com/2015/02/15/magazine/how-one-stupid-t...
How can this be proved? Even with signing, anyone can impersonate anyone.
PGP encrypted public messages is common even on the dark web.
1. Because you trust code for what it is and are willing to trade attribution surety for a lesser ask of contributors
2. Because you care about certain principles of anonymity and non-repudiation and want to respect them in your own plainly legitimate project.
3. Because your project is or risks becoming illegitimate in some jurisdiction and you want to protect your contributors as best you can.
It'd be nice if we can continue to respect these reasons as valid even while allowing other maintainers to exercise different policies.
1. This is not even a moderate ask; using ssh for git transactions is no more or less burdensome than https
2. As has been pointed out, there is no reason or reliable way to verify the identity of a creator's SSH key
3. Real-world example of such a project, or why this matters in the context of (2)?
GitHub exposes your public key via it's API. (Why? I have no idea. I call it a privacy violation) So, you need to create new github identity for every SSH identity that you wish to remain anonymous for, otherwise they just get tied together & one aspect of anonymity is lost.
How does that expose any more information than you do by pushing a commit with a GitHub account?
Having your real name on the GitHub account but not having a commit sig is not really that strong deniability anyway.
If your thinking about some situation where you are being legally hounded because of code (e.g. DMCA, tornado cash situation etc) they will subpoena your hardware and likely find enough evidence that you can't plausibly deny writing the code anyway. GitHub logs may show you the upload was with a SSH key or http auth associated with you anyway.
For non legal situations, I suspect most observers won't really believe that a non-signed upload could have been done by someone else. Especially if it's to a repo only you have upload permission to or something.
Websites from Google search result are verified by my browser via HTTPS certs. On twitter or facebook, users usually trust the centralized authnz systems hosted by the platform to verify content ownership. But out of box, git allows you to use whatever name/email on your commit, so that's a problem.
In my whole career, there were 3 times that I got questioned about "why did you introduce this line of code, which caused some production issue?" and turned out to be results of someone junior developer's rebase/amend or whatnot. I pointed out that I always sign my commits and those unsigned ones were not mine. Without signature I really could not tell whether I was the author or not, since some commits are months/years old.
I believe those altered commits were honest mistakes without malicious intention, and our organization has blameless culture. But I still want to let my coworkers know that I am not the one who caused this problem. Signing commits helps a lot in these situations and clears misunderstanding, and I believe more or less impacted my performance review and bonus (my performance would probably not be as good if I had to own those incidents).
CI/CD tools are getting better each day, a commit can mean a lot more than "a snapshot of the code base", like, it could have been a checkpoint of the state of the production environment (IaC, GitOps ... etc). You already have your name on the commit, so why not offer a way for others to verify you are really who you say you are?
And I should probably clarify, that the identity of a git commit does not have to be linked to a human in real life. It's just a way to verify that a commit is really from author X and not Y.
Systems are typically unsecured until someone starts abusing it. GitHub has obviously foreseen this possibility which is why they have the infrastructure in place to restrict freedom in the interest of security. The day someone starts aggressively misusing that feature, they could take it away just like that.
In most engineering or engineering adjacent fields you are doing this, btw. Yes, in software too.
Of course certain projects (especially if very critical or secure systems) definitely benefit from that but imagine you put your handwritten signature on every single step of your work (hint: you don't do that in the real World). You would never do so for normal internet activity like Google searches, Twitter or Facebook yet you want to sign your git commits with a signature undeniable connected to yourself, probably also connected to your real name.
If you just think that signing is just a "cool feature to have" then you should really educate yourself about implications of having a connected (real name?) identity on the internet.
[1] https://en.wikipedia.org/wiki/Plausible_deniability
[2] https://legaldictionary.net/plausible-deniability/
P.S.: I just wanted to make people think before activating this feature. Most GitHub code and repositories worked perfectly without it. Do you really need it? When yes, why?