You are presented with a file called
Very_old_song.docx, which consists of two pages. At the end of this writeup you will find two screenshots taken from LibreOffice Writer.
This challenge was a bit mean, because you got a docx file, in which a sheet of music was compiled on various graphics. You could have searched with binwalk and similar tools for anomalies in the file for a long time, because the solution was to be found in the semantics of the notes.
If you can read notes, you will immediately notice a few peculiarities:
- There are always eight whole notes to be seen, between which there is always random-looking garbage.
- These sequences consist only of the notes C and D.
- The note D is higher than the note C.
- 8 is obviously an interesting number.
So if you take the value 0 for C and 1 for D, you get 28 bytes. If you convert these 28 bytes to ASCII you get the string
echo "Y3RmezV1Q2hfbjFDM19tVXMhY30=" | base64 -d
Solved by petrosyan