Re:Bitcoin puzzle #66 was solved: 6.6 BTC (~$400k) withdrawn
by n2d4 on Monday September 16, 2024 @05:39PM
(#41561240)
More efficient than brute forcing a private key, as you would have to do when you don't have the public key.
Sure, finding a private key whose public key's hash is given might be 2x slower, but Pollard's rho algorithm is 2^128 times faster.
Asymptotically, an additional hash at the end doesn't matter when you brute force. But it prevents you from using Pollard's rho algorithm, which does make a difference asymptotically.
Having the public key is easier than having an address because an address is the hash of a public key. So in order to crack an address, you must first find a public key that produces that address, and then find a private key corresponding to the public key.