WELL thats great in my eyes.. Then we narrow down who it is.. lock down creating new users so they cant keep swapping users and perform the test every two weeks or less.. If im going to lose 30% earnings for 4 months in a row then i think some countermeasure is needed.. I dont mind throwing away a few seconds of mining to test this theory.. Personally i think there is nefarious reasons why this hasn't been implemented Already and i don't know why you would oppose this eleuthria.. Since we know your pool was obviously victim to it before it shut down.. If i remember right it was nearing 80 % as well and dropping..   these miners need caught their ips made public and lets work on getting this resolved.. I know that you can make this work and send old block solutions to the miners to test them for withholding.. If a miner drops off when the tests are performed they are flagged as suspect then they are tested even harder.  Till they get with the program or they are permanently banned.. I think with this becoming a big issue and the hw becoming more efficient making this attack easier and less costly we have to get something in place..  Maybe the reason this hasnt been done will be used in the future to screw all the public pools and force everyone solo or die.  Lets work together .. stop the bickering of my pools better then yours and come together as a whole and lets try to fix this.

Best Regards
d57heinz


EDIT  and the community would prefer you kept quiet on whether you got it to work or not.. No need to let the attacker know he is being watched.. THATS how you get it done.. Dont update the source code till after you have "tested" it