Interesting. But if something different than SHA256 were implemented, it wouldn’t be compatible with existing backups.
I don’t believe Black2b produces equivalent hashes as SHA3 - it seems to be a different algorithm.
Regarding security - that’s not the purpose of hashing in Duplicati. It’s not used for any cryptographic purposes. I’m not an expert by any means, but I believe the main goals are to use a proven hashing function with good performance while minimizing chances of collision. There’s an inherent conflict here - larger hash size (greater number of bits) reduces chance of collision but increases computation power.