I know that, many thanks! But those are, on one hand, heavily protected wallets and, on the other hand, imagine the consequences if you were to steal one...
I'm asking if it's possible to divert from time to time some hashrate from a large mining pool and to silently crack old lost wallets (very easy passwords, most probably) and so to get 50 easy btc at a time. Clean and repeat, at the expense of pool members... And those would come as free 'bonus' to the actual reward of 25btc..
Have a look at hashrate variation here:
Where does it go approx. 200Th/s?!! Who does it in such a short time and most important why? (It's not so easy to underclock/overclock a mining farm neither to power it on and off) And why does it seem to repeat so frequently and it looks so much like a pattern?!
as i said before... btc miner goes to mining paycoin, but as now they were back.
about cracking wallet : short answer no, long answer yes, for more information pls google address collision
check this :
https://bitcointalksearch.org/topic/what-are-the-chances-of-an-address-collision-and-what-happens-when-it-does-104461
let's apply probability to your scenario.
Let's say there are a billion people using 10 addresses each for 10 billion total addresses.
This means that each address you generate has a (1/2^160)*10,000,000,000 possibility of holding a balance, giving your first attempt a 0.0000000000000000000000000000000000000684% chance of finding a collision on your first attempt.
You are correct in stating that with each try it will either happen or it won't, there is no in-between state, and you're correct in stating that it's possible. It's also bad news for the account holder that a collision would give you control of those funds.
Comparatively speaking, your odds of being struck by lightning in a given calendar year are about 1 in 280,000. The odds of winning my local lottery are about 1 in 176,000,000. So finding a collision on your first try is roughly equivalent to being hit by lightning 16,540,000,000,000,000,000,000,000 times per second for an entire year or winning the lottery 830,000,000,000,000,000,000,000,000,000 times.
If you find a collision I would stay indoors and play the lottery.