Use existing first "0" field for telling that LZMA / LZMA2 decompression is needed before CRC
magnumripper opened this issue · 3 comments
Background: https://hashcat.net/forum/thread-4328-post-32963.html#pid32963
Good job on finding out what we were missing!
I'm not sure of the original idea with the zero in $7z$0$... but it's not used anywhere so I'm pretty sure we can use it as a flag field. This will ensure backward compatibility in a good way - eg. hashes that set LZMA won't be loaded by a version of JtR or Hashcat that doesn't support it (at least that's true for JtR, I didn't look at HC yet).
So I propose we use this field with $7z$1$... meaning LZMA, and $7z$2$... meaning LZMA2.
That's interesting... I had exactly the same idea while troubleshooting the problem and writing the post on hashcat's forum... but I wanted to make sure that this field had no additional meaning (that I wasn't aware of).
Yeah, I will update 7z2hashcat.pl soon.
I think that this updated hash format solves the problem (of the lack of the compression information mentioned on hashcat's forum).
Now it's the time for the crackers to implement/support this.
Can we already close this issue?
Perfect! So now I've got work to do in JtR.