It would depend on the various configuration of the SPV wallet (and those providing it) what other malicious things can be done.
That's the difference between what the protocol is and what the implementation does, and we are talking about the protocol here not a specific implementation of it.
Well that's pointless, since no one will have 'the protocol', they will only have an 'implementation'.
The comment I replied to suggested that a speed up was to use an SPV wallet, and I replied with information regarding the risk if someone was to get such an 'implementation', not a discussion of the 'protocol'.
Using statistical expectation, a block of your choosing with any content you like, costs round 6.25 BTC
So not all that hard to get ...
That is worth $300k, so it
is hard but that's not important. What matter is that the said block will be on a short chain that nobody will build upon:
A > B > C > D > E > F
> D'
where D' is the fake block. The SPV client is capable of noticing this and following the longest chain. If the attacker continues building on D' it still is going to be a lot shorter than the
real chain and won't be followed by the SPV client.
The '$300k' number is effectively meaningless.
It's the 6.25BTC number that matters, and if some scoundrel company with more than 6.25 BTC (which there are plenty of companies with a
lot more than that) wants to take advantage of an implemented SPV wallet with a lot more than 6.25BTC in it, where the SPV wallet only talks to them ...
I wonder why a mod deleted one of my posts and who asked for that ...
![Tongue](https://bitcointalk.org/Smileys/default/tongue.gif)