I could not find a specific "Code Black 2021" write-up or text file for download in current cybersecurity or competitive programming databases. It is possible this refers to a specific Capture The Flag (CTF) challenge or a proprietary internal script.
: This was a notable cryptography/pwn challenge. A detailed write-up and the underlying code logic (Python) can be found on the Black Bauhinia site .
If you are looking for a similar challenge from that timeframe, here are the most relevant matches:
: Use the search query filename:writeup.txt "code black" 2021 to find raw text files in public repositories.
: Search the CTFtime archive for "Black" or "Code Black" filtered by the year 2021.
If this is for a specific CTF or homework assignment, check these common repositories:
: A summary of various write-ups from this 2021 event is hosted on Scribd , though specific "Code Black" files may require a subscription to view.