Função - Gera MD5

SQL: 

create or replace function md5 (valor varchar) return varchar2 is
  v_input   varchar2(2000) := valor;
  hexkey    varchar2(32) := null;
begin
  hexkey := rawtohex(dbms_obfuscation_toolkit.md5(input => utl_raw.cast_to_raw(v_input)));
  return nvl (hexkey, '');
end;

Chamada da função:

select md5('Teste') from dual

Retorno: 

8E6F6F815B50F474CF0DC22D4F400725