Suppose your wallet.dat file is copied to the wild.
I am working on methods for creating very strong (512bits, hopefully much more) passphrases that would make it unfeasible to either use rainbow tables or to try brute force it.
Ideally, even if:
i) one's passphrase is simple; and
ii) the wallet.dat file is copied...
...an adversary would have to employ giant computing power to try to unlock it.
Since I couldn't get it from the documentation, I wonder if anyone knows how large (in, say, bytes) a passphrase/password can be.
related question: How does the Bitcoin client encrypt the wallet.dat file?