Quote from: pebwindkraft on January 31, 2018, 01:33:47 PM

Quote from: rocky3xr on January 30, 2018, 02:33:47 PM

Hi guys, I'm reading "Mastering Bitcoing" and I'm curious about this topic, I read that with 64 hexadecimal you can generate 10^77 seeds and there is 10^80 atoms in the visible universe, but is it possible that you have a seed that already exist? I'm not focus on the probability, just the possibility.

Thanks and regards!

just as another thought on top:
and let's just assume, a collision was found - what is the probably that exactly this bitcoin address contains some spendable funds?

Assuming uniform distribution of the Hash160 (SHA256→RIPEMD160) output, each Bitcoin address can be spent by approximately 2⁹⁴ different keys. (160+94=256) There are numerous posts (indeed, entire threads) on this topic in the forum archives. I regret that I dont have any links handy.

Thus, te proper number to examine in this context is 2¹⁶⁰. As I said above in this thread, that is on the order of 10⁴⁸.

Given that n addresses control spendable funds, where n is a number which can be determined from the public blockchain at any given point in time; and assuming that the n addresses are uniformly distributed throughout the 2¹⁶⁰ search space (viz. that people have working CSPRNGs); what you are asking is the probability of colliding with any of them, when you pick a new address randomly from a uniform distribution.

Working out the precise answer is left as an exercise to the reader. A reader who is more solid with subtle statistical calculations than I amI dont want to give potentially bad information.