The serious part is: I have a little doubt on the viability of RIPEMD160, by the curse of "birthday paradox", approaching 2^80 computation doesn't seem to be too remote.
let me explain in details. lets compare 2^256 to the entire population that we consider in a birthday paradox, and 2^160 be compared to 365 days (number of allowable birthdays). so the paradox says we need 23 members to say with ~50% probability that two may share the same birthday, not someone has the same birthday as us. so in the same way we need 2^80(which P~2^160/2) to say with ~50% that any two private keys in the entire rage of 2^256 have same RIPEMD-160 hash. those two private keys with same public key may or maynot have been used. but what we are doing here is more specifically searching some 30 million addresses for any collision, thats more like someone in the sample waiting to find an other person with same birthday as his and the probabilities for that are different.
please correct me if i am wrong. i dont think 2^80 keys is enough to crack the bitcoin address. its the same old probabilities you have 50% chance if we searched from 1 to 2^159.
