Am I thinking if its really matter to know who gave you karma? From the perspective of the karma, I think it's not important to know the one who gave it. Since if you found out that someone awarded karma to you, it just prove that you're a good poster. Likewise Admin only knew someone who gave it and he can put a negative karma if he founds out that someone is just farming karma on his jurisdiction. Well I guess, that's a relief for those are doing honest work but if you're doing a bad thing better be scared now. For me it's okay I didn't know who gave it to me. I'm thankful that someone has appreciated my post or comment.