From: David Lang Date: Tue, 19 Jul 2016 07:46:50 GMT Subject: Re: Git and SHA-1 security (again) Message-ID: In-Reply-To: On Tue, 19 Jul 2016, Johannes Schindelin wrote: > Hi Duy, > > On Mon, 18 Jul 2016, Duy Nguyen wrote: > >> On Sun, Jul 17, 2016 at 4:21 PM, brian m. carlson >> 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