If you are using Papers alongside a BibTeX file by people writing in LaTeX and similar environments or using SmartCite for Citekeys, we have now added in the ability to autogenerate citekeys.
When importing items into your library you can choose to use the original citekey or choose to overwrite the citekey with the new Citekey Management menu.
Autogeneration of citekeys is only available for personal libraries, though citekeys can be added manually in shared libraries. The reason in shared libraries, users may have different rules for citekey generation that would conflict/change ones being in use by the team. To manually add/edit a citekey, you simply click on the "Edit" pane and scroll to the citekey field, make your edits then click save.