Under Brazilian laws, all adoptions are closed adoptions. No information is exchanged between the natural parents and the adopting parents.
There are multiple definitions - click on the translation that matches your context.
an adoption (=the act of taking legal responsibility for another person's natural child on the same grounds as if it were your own child) where the child's natural parents and the adopting parents do not have personal information about each other such as last name, addresses and social security numbers
The majority of closed adoptions are arranged through an adoption agency.