How can I mask a column or redact the data, Not setting data to NULL combination includes row condit

I have a requirement to show data from single table. Some users must not see certain columns for certain rows.

CREATE table job
(id number not null,
regular_data varchar2(10),
data_security_flag varchar2(1) not null,
sensitive_data varchar2(10))

data_security_flag will have check constraint - values in ('N','C','S')

Some users (with "N" access) can see all rows all columns
Others (with "C" access) can see all rows, but not "sensitive_data" on rows where data_security_flag = 'N'

Our requirement is complicated -- for the "others" -- we need to show something in the hidden column.