After having implemented AES I tried to implement GCM, but failed at doing it from some papers. Then I failed translating it from a reference C implementation t

After having implemented AES I tried to implement GCM, but failed at doing it from some papers. Then I failed translating it from a reference C implementation to scheme. Then I gave up and implemented OCB(3) mode. And I was happy to see that it is now free for all. The parents are lapsed.