Be carefull what you wish for. Accept only the blocks with a valid signature? And who is in charge of giving out those signatures?
The Bitcoin foundation? Verisign? Or maybe, you know, just to prevent fraught for your own safety, the loving goverment or the federal reserve?
Your client(SW) will be verifying. ... I'm talking about really malicious entity .. Chinese government will invest billions into miners(HW) and will build power plant and then use this power to double spend or disallow normal transactions.
Ok. How? Based on what?
E.g. a browser typically has a list of certificates. Basicly the public keys, not really different from the bitcoin addresses (thats basicly also just the public key).
And well, someone has to compile that list.
So, even if i repeat myself, who? "The Bitcoin foundation? Verisign? Or maybe, you know, just to prevent fraught for your own safety, the loving goverment or the federal reserve?".
I mean, if you really have a good sultion i´m pretty sure the whole internet would want to know. There have been enough issues with the current CA-system in the recent years and its time someone came up with a good solution.
I do not think, it is best solutions and I'm sure somebody will bring better (there exists solution for everything).
Example:
1. Everybody sees his transactions are not processed or a lot of double spending.
2. New thread will start @ bitcointalk :-) (why my transaction are not accepted ... reason will be found.)
3. Pool's operators will say "we do not do malicious things if you believe us then accept block with this signature".
4. Some anonym operator/miner will do the same. This is my public-key. (you do not have to know his identity)
5. some group of honest miner will formed.
6. You can see who broadcast bad blocks or do not provide signatures.
7. New client is released ... you can configure what signatures you will accept.
8. you can choose new group of miners ... or use old one, but that is malfunctioning.
... majority will be formed :-)