How much hash will be selected and how many resources will be needed for this?

Question

Hashing

Good afternoon, just for the sake of curiosity, I want to ask you how much md5 hash will be selected using this mask:
?????????.??.??????????????????
where:
? - any number from 0 to 9
. - immutable symbol
And how many resources will be needed for this?)

Answer 1

You are asking about a preimage attack. For md5 we know about the existence of an attack with a complexity of 2 ^123.4 . If you sort through the masks in the forehead, then 29 decimal digits give 97 bits, i.e. complexity of direct selection 2 ⁹⁷ . We can say that for this use, md5 is still good. Based on the estimate "NVIDIA GeForce 8800 Ultra can calculate more than 200 million hashes per second", we get that direct mask selection will take about 2 ⁹⁷ / 10 ⁸ = 1.6 * 10 ²¹ seconds of operation of one such card. Those. 5 * 10 ¹³ years old.