In hashcat, how does one specify that the given hashes have been reduced to a specific length? I.e. the stored hashes that are to be solved are truncated versions of what the hash function provides?
As of the current version (3.30), hashcat does not currently support truncated hashes beyond the half-MD5 modes. In my discussions with the team, I made the pitch (basically what I wrote here).
So far, they have expressed non-interest in expanding partial-hash matching to other types, as it's considered to be out of scope for the project. But this could change in the future.