Cabal's use of GHC.Fingerprint

Hi,

We are looking to change the fingerprint hash function in GHC as md5 is quite slow[1].

However it seems that Cabal has used this module internally to implement Backpack's fingerprinting and elsewhere with the assumption that the algorithm is MD5.

So I am trying to get an idea of what the breakage would be if we change the algorithm and how we can mitigate the problem.

[1] https://gitlab.haskell.org/ghc/ghc/-/merge_requests/4248