Migrate unknown Oracle database user's encrypted password - 11g hash to 12c database

I have tried to search extensively but could not find.Oracle has changed the encryption (spare4) in 12c. I am trying to see if its possible to migrate / copy the encrypted password hash of a user in 11g database to 12c. I have done this before on 11g to 11g, but not able to replicate / find how to do this on 11g to 12c. Thanks!