12-08-2019, 09:07 PM
option 1 is basically the most flexible one that can accomodate for all other modes (the user can just pass the correct password candidates according to keying options).
The main other problem is how to set the last 8 bytes equal to the first 8 bytes in your particular case... but this is NOT even the worst problem, because you are trying to brute-force it with basically 112 bits (2 * 56 bits, which would be 14 bytes, instead of the full 8*2=16 bytes, due to some security properties it's actually known to have only 80 bits of security, see https://en.wikipedia.org/wiki/Triple_DES), which is even in case of a meet-in-the middle quite difficult/infeasible to brute-force in a reasonable amount of time.... you probably need to know more about the (weakness of the) keys to make it feasible and pass the candidates e.g. with an external generetor over pipe where you set K1=K3.
I wouldn't say it's a problem of hashcat (even though one could argue why there is not a dedicated mode for each and every keying option, that's a fair and valid point), but just a problem of complexity and infeasibility (because of too many possible keys/password candidates, at least if you have no further knowledge about some of the bytes or some non-random generation process).
The main other problem is how to set the last 8 bytes equal to the first 8 bytes in your particular case... but this is NOT even the worst problem, because you are trying to brute-force it with basically 112 bits (2 * 56 bits, which would be 14 bytes, instead of the full 8*2=16 bytes, due to some security properties it's actually known to have only 80 bits of security, see https://en.wikipedia.org/wiki/Triple_DES), which is even in case of a meet-in-the middle quite difficult/infeasible to brute-force in a reasonable amount of time.... you probably need to know more about the (weakness of the) keys to make it feasible and pass the candidates e.g. with an external generetor over pipe where you set K1=K3.
I wouldn't say it's a problem of hashcat (even though one could argue why there is not a dedicated mode for each and every keying option, that's a fair and valid point), but just a problem of complexity and infeasibility (because of too many possible keys/password candidates, at least if you have no further knowledge about some of the bytes or some non-random generation process).