User roles and privilages

Hi All,

This maybe a silly question and I have done some google searches but not really found anything useful so far!

I have a user which has read rights to all packages/views/functions/tables etc via a SELECT role, which works perfectly fine.

For one user we want the same privileges assigned except for a specific package (called encryption) for obvious reasons so this user cannot decrypt password etc.

I basically wanted to revoke privileges on this package for this user

I tried revoking the privilege via sqlplus and get the following:

ERROR at line 1:

ORA-01927: cannot REVOKE privileges you did not grant