HUB table creation in DV SCD type2

Question

Looking for recommendations for HUB table creation with multiple business key. which one is advisable to create single HUB table like below?For e.g.

 create table h_x
(
hkey,  --> sha2(a_bkey,256)
load_dt,
rec_src_cd,
a_bkey,
b_bkey,
c_bkey

)
or 

create table h_x
( hkey, → sha2(a_bkey+‘-’+b_bkey+‘-’+c_bkey,256)
load_dt,
rec_src_cd,
a_bkey+‘-’+b_bkey+‘-’+c_bkey as bkey

)