I'm messing around with bitcoins a bit, and I'm now looking at the confirmations. In several places I read that 6 is the "normal" figure of confirmations needed to say a transactions has actually and irreversibly occurred. I also read this excellent Q, which explains a lot more.
I still wonder about one thing though: in the case of bad intentions, how big is the chance of double spending in the case of 0, 1, 2, 3, 4, 5 and 6 confirmations expressed in percentages?
I'm after a little table which should look something like this:
confirmations | chance of double spending (all figures are made up)
-----------------------------------------
0 | 10%
1 | 4%
2 | 1%
3 | 0.5%
4 | 0.2%
5 | 0.05%
6 | 0.001%
hash-power^confirmations
wherehash-power
is percent of network hashing you have. Note how for 0 confirmations on any hashing power you have 100% chance to double spend. This of course assumes network is perfect.