With "pb_sv_noguidgrace 0" players without key wont get kicked.

To create a new key you could use a simple batch file like this:
echo Date: %DATE% Time: %TIME% User: %USERNAME% Hostname: %COMPUTERNAME% OS: %OS% CPU: %Processor_Identifier% CPU Arch: %Processor_Architecture% Cores: %Number_Of_Processors% CPU Rev: %Processor_Revision% CPU Level: %Processor_Level% Key: %RANDOM%%RANDOM%%RANDOM%%RANDOM%%RANDOM%%RANDOM%%R ANDOM%%RANDOM% >>etkey
The content of the etkey will be uniqe and looks like that:
Date: 06.10.2011 Time: 11:21:27,92 User: XXXX Hostname: XXXX OS: Windows_NT CPU: Intel64 Family 6 Model 23 Stepping 10, GenuineIntel CPU Arch: AMD64 Cores: 2 CPU Rev: 170a CPU Level: 6 Key: 8520869304115926136983156860617966
Thats no big deal and other informations could be easy added.

And who knows if you edit an existing key you could create a duplicate of a existing (of course only one you created before)

Well i could be wrong and this is only a simple idea. We are still looking for a solution for our own gameserver.