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Linus Torvalds did not commit this

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Re: Linus Torvalds did not commit this

#141

Post by pornel »

Argorak wrote: post #73

The issue at hand here is interesting: GIT _commit_ integrity is not guaranteed over all operations, even if you sign commits. The problem is that GIT often changes commit details. If you, for example, rebase or cherry-pick a commit, the identity changes - as the commit includes a reference to the parent commit(s). This means that once you do any of those (standard) operations, the signature becomes invalid. Signing…

IMHO git does it right. If signature was only at the commit level you could do a variant of replay attack.

For example you could cherry-pick all commits except security fixes and create a malicious version of the software that has all commits still signed by the original author.

Re: Linus Torvalds did not commit this

#142

Post by simoncion »

arihant wrote: post #104
cbd1984 wrote: post #92

Earlier quoted context omitted.

It being a "Git issue" implies it should be fixed by modifying the Git software. I'm not entirely sure how someone would go about doing that, assuming you can't assume that each machine generating contributions will only be used by a single contributor and never shared. (Tokens such as thumb drives can be stolen and copied, too, and an application can't be sure it's reading off a thumb drive anyway.)

By appending "unverified" and "unsigned" after the email addresses? Just like email. This problem has been solved long ago, there is no reason why Git can't fix this. It already has PGP signatures, there is no reason to not add verification layer.

> [Git] already has PGP signatures, there is no reason to not add verification layer.

It already does.

man 1 git-verify-commit

man 1 git-verify-tag

This is a Github problem.

Re: Linus Torvalds did not commit this

#143

Post by gertef »

WalterBright wrote: post #117
ectoplasm wrote: post #107

Earlier quoted context omitted.

To me this sounds like admin trying to save money. I found some more discussion in a couple places: http://blog.sethroberts.net/2014/02/17/cheating-at-caltech/ https://www.quora.com/Are-all-exams-at-Caltech-take-home-exa...

That's the first I've heard that it had anything to do with saving money, and I spent 4 years there. It does, however, make life easier for professors and students when you can trust each other. I don't know what Caltech is like today. I attended in 70's, and the honor system was considered sacred by the students. If there were cheaters, they never bragged about it, and I don't know of any. I know one who fell asleep…

> The professor replied back that he was very sorry and was forced to give him an F. The student repeated the (required) class next year.

Wow, way to prize process over people. Why not let the student drop the class and just re-take the test next time around?

Is Caltech designed to teach science, or train paper-pushers?

Re: Linus Torvalds did not commit this

#144

Post by vacri »

WalterBright wrote: post #71
ultramancool wrote: post #28

Earlier quoted context omitted.

I love this. Had a project in college that was supposed to be time limited... based on repository times. Oops. Big mistake prof. We rolled back the times on our repo and laughed maniacally about our free 6 hour extension.

Should professors really be spending their time locking down all the ways students may try to cheat? At Caltech, proctoring exams (for example) is not allowed by institute policy. A student's honor that he didn't cheat is considered good enough.

> A student's honor that he didn't cheat is considered good enough.

Individual students certainly can have this integrity, but the demographic as a whole is demonstrably susceptible to cheating.

It also offends basic scientific process, in that it suggests that you don't need to bother with trying to make sure your results are robust; instead it relies on someone's word. Why bother having exams, then? Just ask "Do you think you understand the course material properly"?

Re: Linus Torvalds did not commit this

#145

Post by undrcvr-lagggal »

jrv wrote: post #93

Linus actually commented on this lack of identity handling in 2012 in his famous explanation of why he doesn't use GitHub: https://github.com/torvalds/linux/pull/17 "since github identities are random, I expect the pull request to be a signed tag, so that I can verify the identity of the person in question." And: "github throws away all the relevant information, like having even a valid email address for the person a…

He called github "braindamaged". Isn't that against the CoC?

Re: Linus Torvalds did not commit this

#146

Post by simoncion »

hk__2 wrote: post #105
comrade1 wrote: post #72

This is more of a problem with GitHub than git. Remember, it's not that hard to host your own git repo. There's no need to use GitHub.

This has nothing to do with GitHub. The commit author field in Git is like the “From” field of an email; you can put whatever you want in it.

This has everything to do with GitHub.

Git provides mechanisms to sign both commits and tags, and to verify those signatures. GitHub fails to make use of those mechanisms.

Re: Linus Torvalds did not commit this

#147

Post by dragonwriter »

undrcvr-lagggal wrote: post #145
jrv wrote: post #93

Linus actually commented on this lack of identity handling in 2012 in his famous explanation of why he doesn't use GitHub: https://github.com/torvalds/linux/pull/17 "since github identities are random, I expect the pull request to be a signed tag, so that I can verify the identity of the person in question." And: "github throws away all the relevant information, like having even a valid email address for the person a…

He called github "braindamaged". Isn't that against the CoC?

> He called github "braindamaged". Isn't that against the CoC?

So, you think he violated a Code of Conduct that did not exist at the time, in the course of explaining why he was not a user of the service (so that any Code of Conduct for that service would not apply to him even if it existed.)

Re: Linus Torvalds did not commit this

#148

Post by dragonwriter »

tgb wrote: post #89
WalterBright wrote: post #71

Earlier quoted context omitted.

Should professors really be spending their time locking down all the ways students may try to cheat? At Caltech, proctoring exams (for example) is not allowed by institute policy. A student's honor that he didn't cheat is considered good enough.

Why wouldn't you proctor exams? The time spent is small, less than 10 hours a semester, and the proctors can answer student questions or make corrections and clarifications to test questions. That it's a small disincentive to cheat is nice too, though in my experience only the most blatant of cheating would be caught. I say all this as someone who proctors exams.

> Why wouldn't you proctor exams? The time spent is small, less than 10 hours a semester, and the proctors can answer student questions or make corrections and clarifications to test questions.

Because Caltech faculty (and, for undergraduate student exams, grad students) have better things to do with their time than proctor exams (and, perhaps more to the point, because Caltech wants to attract faculty and grad students that feel that they have better uses for their time that baby-sitting exams.)

And, frankly, like many aspects of the trust extended to Caltech students, its a recruitment policy -- Caltech is an extremely selective, extremely small school that is competing with other elite institutions to attract the best students.

Re: Linus Torvalds did not commit this

#149

Post by Argorak »

pornel wrote: post #141
Argorak wrote: post #73

The issue at hand here is interesting: GIT _commit_ integrity is not guaranteed over all operations, even if you sign commits. The problem is that GIT often changes commit details. If you, for example, rebase or cherry-pick a commit, the identity changes - as the commit includes a reference to the parent commit(s). This means that once you do any of those (standard) operations, the signature becomes invalid. Signing…

IMHO git does it right. If signature was only at the commit level you could do a variant of replay attack. For example you could cherry-pick all commits except security fixes and create a malicious version of the software that has all commits still signed by the original author.

I was not saying that the signature is _just_ at a commit level ("patches" being the DARCS lingo).

DARCS, just as git, has tags for that. A tag depends on all previous patches, so a signed tag guarantees just the same as a signed git tag does.

In that regard, git is strictly less powerful.

Re: Linus Torvalds did not commit this

#150

Post by chrisfosterelli »

WalterBright wrote: post #71
ultramancool wrote: post #28

Earlier quoted context omitted.

I love this. Had a project in college that was supposed to be time limited... based on repository times. Oops. Big mistake prof. We rolled back the times on our repo and laughed maniacally about our free 6 hour extension.

Should professors really be spending their time locking down all the ways students may try to cheat? At Caltech, proctoring exams (for example) is not allowed by institute policy. A student's honor that he didn't cheat is considered good enough.

At my school many, many students cheat. This devalues the education that I'm getting and is frustrating to students who actually put in the time to study.
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