The 5 missing bytes will still be 256 * 256 * 256 * 256 * 256 = 256 ^ 5 = 1099511627776 combinations.
That's a quite huge keyspace, even if the hashing algortihm (keccak) is quite fast.
of course with a huge prefix (the very long 59 "salt" because of the 59 known bytes) it would be better to have a more dedicated hash mode, like salted keccak e.g. by speficing the hash like
(i.e. salt:[59bytesPrefix])
(btw: salted keccak is not implemented yet )
The mask attack for -m 5000 would be -a 3 --hex-charset keccak_hash_file.txt [59bytesPrefix]?b?b?b?b?b02
of course the [59bytesPrefix] must be replaced by the known bytes (in hexadecimal)
but again, this might be infeasible (depending on your setup etc).
I think it would be still more clever to try to find the correct password (much less tries, possibilities ? no real bruteforce, but word list + rule attack ?).
In all cases, I would suggest that you generate some example hashes with the same version that you generated the old seed and try to crack them just to make sure that you are doing everything right and not wasting time (i.e. try examples of cracking with 16300 and also with -m 5000 with hashes/seeds generated by the presale wallet/seed generator etc).
BTW: I know that the pre-sale web page generated a much longer seed, because there where complains/rumours that the mouse movements for the entropy + timing etc was not that good of a random number/byte generator. The website used to generate up to 608 byte seeds as far as I know... but if you got your eth earlier you might have a shorter seed. I would double-check this too
That's a quite huge keyspace, even if the hashing algortihm (keccak) is quite fast.
of course with a huge prefix (the very long 59 "salt" because of the 59 known bytes) it would be better to have a more dedicated hash mode, like salted keccak e.g. by speficing the hash like
Code:
hash:salt(btw: salted keccak is not implemented yet )
The mask attack for -m 5000 would be -a 3 --hex-charset keccak_hash_file.txt [59bytesPrefix]?b?b?b?b?b02
of course the [59bytesPrefix] must be replaced by the known bytes (in hexadecimal)
but again, this might be infeasible (depending on your setup etc).
I think it would be still more clever to try to find the correct password (much less tries, possibilities ? no real bruteforce, but word list + rule attack ?).
In all cases, I would suggest that you generate some example hashes with the same version that you generated the old seed and try to crack them just to make sure that you are doing everything right and not wasting time (i.e. try examples of cracking with 16300 and also with -m 5000 with hashes/seeds generated by the presale wallet/seed generator etc).
BTW: I know that the pre-sale web page generated a much longer seed, because there where complains/rumours that the mouse movements for the entropy + timing etc was not that good of a random number/byte generator. The website used to generate up to 608 byte seeds as far as I know... but if you got your eth earlier you might have a shorter seed. I would double-check this too