Post
Topic
Board Development & Technical Discussion
Re: Is it possible to generate an already existing seed?
by
nullius
on 31/01/2018, 13:52:22 UTC
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 don’t 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 am—I don’t want to give potentially bad information.