I have a few ideas for features that involve checksumming raw files (CR2 in my case). Unless I'm mistaken, the CR2 files typically do not get modified in normal use. So a checksum taken on the day it is ingested, should be the same years later. I would say MD5 for the checksum method, but more options are always good. I know that with MD5 that changing the filename won't change the checksum.
Here are my idea for the checksumming features:
1. on ingest, checksum the files on the memory card and compare that to the files that have been transferred over to the primary and secondary destinations to ensure that the copy completed without issue. This could be conducted after ingest to hopefully alleviate any caching issues.
2. generate a checksum of the raw files in a folder/contact sheet and store that data in the XMP side car for that file. The checksum generated in the previous idea could be used here.
3. add a function in the menu that can read the checksum field from the XMP on request and let the user know of any mismatches in a folder/contact sheet
I haven't noticed any issues on ingest yet, so 2 and 3 would be much more important to me. Especially after a drive issue/failure, you could use #3 to quickly and easily verify files and restore good copies from backup if needed. Storing the checksum in the XMP sidecar file removes the need for a catalogue.