Based on rpmdev-md5 script from Enrico Scholz, I made one for sha1 and one for sha256 because I use this functionality from time to time. Feel free to add those small scripts to your repository if you like them.
attachment rpmdev-sha1
rpmdev-sha1 rpmdev-sha1.2
rpmdev-sha256 rpmdev-sha256
Thanks for the suggestion; I opted to make rpmdev-md5 check the name by which it is called with and invoke the corresponding checksum tool, and installing it with a bunch of names (hardlinked) instead of shipping a bunch of nearly copies instead, see [6206e1c5991afce4cb8838efd1043407f24139a2].