Sean Whitton <spwhitton@spwhitton.name> writes: > Hello, > > On Sat 30 Mar 2024 at 12:19pm +01, Simon Josefsson wrote: > >> Relying on signed git tags is not reliable because git is primarily >> SHA1-based which in 2019 cost $45K to do a collission attack for. > > We did some analysis on the SHA1 vulnerabilities and determined that > they did not meaningfully affect dgit & tag2upload's design. Can you share that analysis? As far as I understand, it is possible for a malicious actor to create a git repository with the same commit id as HEAD, with different historic commits and tree content. I thought a signed tag is merely a signed reference to a particular commit id. If that commit id is a SHA1 reference, that opens up for ambiguity given recent (well, 2019) results on SHA1. Of course, I may be wrong in any of the chain, so would appreciate explanation of how this doesn't work. /Simon
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