Quote from: uck on October 18, 2013, 01:50:25 AM

Quote from: Alty on October 14, 2013, 07:50:38 PM

I'm not a computer wizzard but I read somewhere it would take between 1 and 10 billion years for a normal computer to hack a private key, how can anybody take those bitcoins?

http://miguelmoreno.net/wp-content/uploads/2013/05/fYFBsqp.jpg

Teamwork!

Hack a private key = brute force

How many private keys can a normal computer try each second? Feel free to be generous. A trillion you say? Whoa, but ok. 2^40. How many computers on your team? Be generous. A trillion you say? Whoa, another 2^40. Wow, every second the team is trying 2^80 private keys. There are about 2^25 seconds in a year. So, that first year the team knocks down 2^105 private keys, nice. So, in the first trillion years the team (we'll call them a dedicated bunch) will get 2^145 private keys done. Oh, darn the end of the universe is coming up and we are still short by a factor of 2^256/2^145=2^111. Oh, we're gonna need faster than normal computers and a really big team.