--
-- crypt() and gen_salt(): md5
--
select crypt('', '$1$Szzz0yzz');
               crypt                
------------------------------------
 $1$Szzz0yzz$To38XrR3BsbXQW2ZpfKjF1
(1 row)

select crypt('foox', '$1$Szzz0yzz');
               crypt                
------------------------------------
 $1$Szzz0yzz$IYL49cd3t9bllsA7Jmz1M1
(1 row)

create table ctest (data text, res text, salt text);
insert into ctest values ('password', '', '');
update ctest set salt = gen_salt('md5');
update ctest set res = crypt(data, salt);
select res = crypt(data, res) as "worked" from ctest;
 worked 
--------
 t
(1 row)

drop table ctest;