Patrick,
[Brazilian law nº 9.609/68][1] recognizes the legitimacy of the software
licenses (cap. IV, art. 9º). As [copyleft is copyright used in certain
ways][2], and [Brazilian law nº 9610/68][3] recognizes software as
copyrightable (cap. I, art. 7º, XII), GPL is guaranteed.
You were afraid of they removing your name from the software: this second law
gives to the author the irrevocable (art. 27º) moral right to be cited as so
(art.24, II).
[1] http://www.planalto.gov.br/ccivil_03/Leis/L9609.htm
[2] https://www.gnu.org/copyleft/
[3] http://www.planalto.gov.br/ccivil_03/Leis/L9610.htm
