Yes, you can crack it with hashcat, but you need to patch the kernel.

I really love such home-cooked algorithms. They always do something stupid, so does this one. I didn't write a poc, but I'm pretty sure you can actually exploit it. All you need to do is to compare a final value (in your example the c4) already after the first iteration. This way you can skip the entire rest of the calculation if it doesn't match at that point completely and try the next key. You can do the same for the 2nd, and so one. Doing this you will end up with a performance close to the one from raw DES instead of DES speed divided by 8.

I really love such home-cooked algorithms. They always do something stupid, so does this one. I didn't write a poc, but I'm pretty sure you can actually exploit it. All you need to do is to compare a final value (in your example the c4) already after the first iteration. This way you can skip the entire rest of the calculation if it doesn't match at that point completely and try the next key. You can do the same for the 2nd, and so one. Doing this you will end up with a performance close to the one from raw DES instead of DES speed divided by 8.