[Hakkin]

I also thought it was odd. There's also different random bytes (not random text, actual random bytes) prefixed to the start the scripts, but the bytes are prefixed by a hash symbol, which comments them out, so they don't affect the script. It seems intentional, but I can't think of why they would be there. I thought maybe xz would skip compression if the input was short/not complex enough or something, so they were added to pad the size, but removing them and re-compressing with xz seems to properly compress it, none of the original plaintext is in the compressed archive bytes.

One thing I noticed while trying to reproduce the exact bytes included in the .xz file committed to git is that the script's xz stream doesn't seem to be compressed by any of the default xz presets, I was only able to reproduce it by using `xz --lzma2=dict=65536 -c stream_2`. All the default numbered presents chose a different dictionary size. Another odd seemingly intentional choice, but again I don't understand the reasoning.

[Hakkin]

Ah, I think I understand the random bytes at the start of the script now. They're prepended to make the partial output of the "corrupted" (pre-tr'd) test stream look like random data. Without those random bytes, you will see part of the start of the script if you observe the partially decompressed output before xz throws an error. They really thought quite carefully about hiding this well.

Still not sure about the repeated lines, though now I'm convinced there must be some reason for it.