Re: Git and SHA-1 security (again)

From: David Lang <david@lang.hm>
Date: Jul 19, 2016, 07:46 UTC
Message-ID: <alpine.DEB.2.02.1607190045240.2015@nftneq.ynat.uz>
In-Reply-To: <alpine.DEB.2.20.1607190926420.3472@virtualbox>

On Tue, 19 Jul 2016, Johannes Schindelin wrote:

Show 22 quoted lines

> Hi Duy,
>
> On Mon, 18 Jul 2016, Duy Nguyen wrote:
>
>> On Sun, Jul 17, 2016 at 4:21 PM, brian m. carlson
>> <sandals@crustytoothpaste.net> wrote:
>>> I'm going to end up having to do something similar because of the issue
>>> of submodules.  Submodules may still be SHA-1, while the main repo may
>>> be a newer hash.
>>
>> Or even the other way around, main repo is one with sha1 while
>> submodule is on sha256. I wonder if we should address this separately
>> (and even in parallel with sha256 support), making submodules work
>> with an any external VCS system (that supports some basic operations
>> we define).
>
> It is safe to assume that any project using a submodule with a more secure
> hash would require Git tooling capable of said hash. It would hence make
> no sense to use SHA-1 for the super project.
>
> So I do not believe that we have to support the use case of a SHA-1-based
> project using SHA-256-based submodules.

they have different upstreams, what if the upstream of the submodule has upgraded and is using signed commits of the sha-256 but the upstream of the parent hasn't and is using signed commits of sha1?

David Lang