The difference is that the software is in active use in your scenario. Consider if you took a copyrighted program and calculated the sha hash of it. You can the

The difference is that the software is in active use in your scenario. Consider if you took a copyrighted program and calculated the sha hash of it. You can then use that hash without needing to have a copy of the original program. The hash is also not infringing, because it's a simple fact.