Thanks a lot.

I knew the hot wallet is very risky, but I like hot wallet :-)

I think the cold wallet is difficult to operate, and the cold wallet will prevent some user to get they bitcoins if they want to withdraw cash , so I don't like cold wallet.

I use LFS to create a very security trading platform, so I don't worry about system security. Because I already change almost all the Linux kernel syscall, make the root user will not get the bitcoin. In addition, I rewrite the bitcoin RPC, and more.

So I only have one question:
If someone know many many bitcoin address of my wallet, and can get the file "wallet.dat", but not know the wallet passphrase. Does he or she can spend all the bitcoin in some days?

If the answer is yes. Maybe I will use two hot wallet.

I will release my platform in next month, and all users can get the root privileges. But, I believe the root user can't get any bitcoin.

Thanks again.