Append newly collected nonces to existent file

[unkernet]

[aczid]

Can you explain a bit about the use case for this PR? In my estimation, going back to resume an earlier (failed) session by adding more nonces to an already determined system is not all that helpful. In fact it should only be required for 'hard' keys in which many candidate states remain to be tested. For such 'hard' keys, I agree it could be useful.

That being said I believe more effort should be focused on lifting the proxmark3 implementation of the hard nested attack, which in my experience also does better at cracking such 'hard' keys.

[unkernet]

Here is my real use case: I have a limited time to collect nonces for as much sectors as I can, then I need to return the card. So I collecting nonces until the search space can be derived and then moving to the next sector. If I have collected nonces for the all sectors and still have a time, I can collect some more to reduce complexity.